2 cargador fronta 950 h cat

SERV1824
October 2006
TECHNICAL PRESENTATION
950H AND 962H WHEEL LOADERS
AND
IT62H INTEGRATED TOOLCARRIER
Service Training Meeting Guide
(STMG)
GLOBAL SERVICE LEARNING

950H AND 962H WHEEL LOADERS AND
AUDIENCE
Level II - Service personnel who understands the principles of machine system operation,
diagnostic equipment, and procedures for testing and adjusting.
CONTENT
This presentation describes the location of the basic components on the engine, and the
operation of the power train, implement, steering, and brake systems for the 950H and 962H
Wheel Loader. This presentation may be used for self-paced and self-directed training.
OBJECTIVES
After learning the information in this presentation, the technician will be able to:
1. Locate and identify the major components in the C7 ACERT™ engine, power train,
implement, steering, and brake systems;
2. Explain the operation of each component in the power train, implement, steering, and
brake systems; and
3. Trace the flow of oil through the power train, implement, steering, and brake systems.

GLOBAL REFERENCES
Specalog:
950H Wheel Loader AEHQ5675
962H Wheel Loader AEHQ5676
IT62H Integrated Toolcarrier AEHQ5677
Service Manual:
950H, 962H Wheel Loader, and IT62H Integrated Toolcarrier RENR8860
Parts Manuals:
Aurora Built Machines
950H PIN K5K SEBP3866
962H PIN K6K SEBP3874
Gosselies Built Machines
950H PIN N1A SEBP3845
962H PIN N4A SEBP3846
Brazil Built Machines
950H PIN M1G SEBP4274
962H PIN M3G SEBP4283
IT62H PIN M5G SEBP4282
Training Materials:
TIM "966G/972G Series II Wheel Loader Command Control Steering" SERV2660
The following training materials are on SERV1000 the Legacy DVD Set.
TIM "950G/962G Wheel Loader Steering and Braking" SEGV2643
TIM "966G/972G Series II Wheel Loader Command Control Steering" SEGV2660
TIM "950G/972G Wheel Loader Power Train" SEGV2642
STMG "950G/972G Wheel Loader Introduction SESV1698
Estimated Time: 30 Hours
Visuals: 209
Form: SERV1824
Date: 10/06
© 2006 Caterpillar Inc.
SERV1824 - 3 - Text Reference
10/06

TABLE OF CONTENTS
INTRODUCTION ..................................................................................................................9
Component Location.......................................................................................................11
ENGINE................................................................................................................................13
Engine Electrical Block Diagram...................................................................................14
Speed/Timing Sensors ....................................................................................................17
Engine Speed/Timing Calibration Port...........................................................................18
Fuel System.....................................................................................................................19
Fuel Transfer Pump.........................................................................................................21
Power Derate...................................................................................................................22
High Fuel Filter Restriction Derates...............................................................................25
Engine Inlet Air System..................................................................................................27
Turbo Inlet Pressure Sensor............................................................................................29
Air Inlet Restriction Derate ............................................................................................30
Engine Oil Pressure Sensor ............................................................................................31
Low Oil Pressure Derate.................................................................................................32
Engine Coolant Temperature Sensor ..............................................................................33
High Coolant Temperature Derate..................................................................................34
Intake Manifold Sensors.................................................................................................35
Intake Manifold Air Temperature Sensor Derate ..........................................................37
Virtual Exhaust Temperature Derate ..............................................................................38
Engine Idle Management System (EIMS)......................................................................44
POWER TRAIN ...................................................................................................................46
Power Train Electrical System .......................................................................................47
Engine Start Switch and Diagnostic Service Tool Connector........................................52
Transmission Shift Lever................................................................................................53
Transmission Shift Control.............................................................................................54
Transmission Oil Temperature Sensor............................................................................61
Left Brake Pedal Position Sensor...................................................................................62
Implement Pod Downshift Switch and Remote F-N-R Switch .....................................63
Parking Brake Pressure Switch.......................................................................................64
Back-up Alarm................................................................................................................67
Warning Panel - Left Side ..............................................................................................68
Implement Control Valve - with Ride Control...............................................................69
Secondary Steering Intermediate Relay..........................................................................70
Engine Start Relay ..........................................................................................................71
Transmission Hydraulic System - NEUTRAL...............................................................72
Transmission Modulating Valve - NO COMMANDED SIGNAL ................................80
Transmission Modulating Valve - COMMANDED SIGNAL BELOW MAXIMUM ..81
Transmission Modulating Valve - COMMANDED SIGNAL AT MAXIMUM............83
Transmission Modulating Valve - Solenoids..................................................................85
Transmission Relief Valve..............................................................................................87
Remote Pressure Taps.....................................................................................................91
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TABLE OF CONTENTS (continued)
Variable Shift Control.....................................................................................................93
Integrated Brake System.................................................................................................94
Left Brake Pedal Actions................................................................................................95
Speed Limiter..................................................................................................................97
IMPLEMENT ELECTROHYDRAULIC SYSTEM............................................................98
Implement Electronic Control System ...........................................................................99
Implement Control Levers............................................................................................106
Fine Modulation............................................................................................................109
Autodig Control Arrangement ......................................................................................111
Implement Hydraulic System - HOLD.........................................................................114
Tilt Control Valve - HOLD...........................................................................................116
Implement Hydraulic System - DUMP ........................................................................117
Pressure Compensator Valve - HOLD..........................................................................118
Load Check Operation..................................................................................................119
Pressure Compensator Operation .................................................................................120
Implement Hydraulic System - DUMP ........................................................................124
Implement Hydraulic System - RAISE ........................................................................126
Implement Hydraulic System - FLOAT .......................................................................128
Implement Hydraulic System - TILT BACK AND RAISE.........................................130
Implement Hydraulic System - RIDE CONTROL AUTO...........................................132
Ride Control Valve - AUTO/TRAVEL BELOW 9.7 KM/H (6 MPH) ........................134
Ride Control Valve - AUTO/TRAVEL MORE THAN 9.7 KM/H (6 MPH)...............135
Implement Pump and Pump Control Valve..................................................................138
Pump Control Valve - ENGINE OFF...........................................................................139
Pump Control Valve - LOW PRESSURE STANDBY.................................................141
Pump Control Valve - UPSTROKE..............................................................................142
Pump Control Valve - CONSTANT FLOW DEMAND ..............................................143
Pump Control Valve - MAXIMUM SYSTEM PRESSURE........................................144
Pump Control Valve -
MAXIMUM SYSTEM PRESSURE WITH ADDED FLOW DEMAND...................145
Implement Valve...........................................................................................................146
Margin Relief Valve......................................................................................................147
Pressure Reducing Valve - BELOW THE ADJUSTED SETTING.............................148
Pressure Reducing Valve - ABOVE THE ADJUSTED SETTING .............................149
Load Sensing Pressure Tap...........................................................................................150
Signal Duplication Valve ..............................................................................................154
Signal Relief Valve - BELOW ADJUSTED PRESSURE SETTING..........................155
Signal Relief Valve - ABOVE ADJUSTED PRESSURE SETTING ..........................156
Line Relief Valve - BELOW RELIEF SETTING........................................................157
Line Relief Valve- ABOVE RELIEF SETTIN ............................................................159
Line Relief Valve - MAKEUP FUNCTION.................................................................160
Quick Coupler System..................................................................................................162
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HAND METERING UNIT (HMU) STEERING SYSTEM ..............................................165
Steering Pump...............................................................................................................169
Steering Pump - ENGINE OFF....................................................................................170
Steering Pump - LOW PRESSURE STANDBY..........................................................171
Steering Pump - UPSTROKE.......................................................................................172
Steering Pump - DESTROKE ......................................................................................173
Steering Pump - HIGH PRESSURE STALL ...............................................................174
Steering Control Valve..................................................................................................175
Steering Neutralizer Valves ..........................................................................................176
Steering System - HOLD..............................................................................................178
Steering System - GRADUAL LEFT TURN...............................................................180
Steering System - FULL LEFT TURN WITH STEERING NEUTRALIZED............181
Secondary Steering System ..........................................................................................182
Secondary Steering System - GRADUAL LEFT TURN.............................................186
COMMAND CONTROL STEERING (CCS) SYSTEM...................................................188
Quad Check Valve ........................................................................................................191
Steering Pilot Valve ......................................................................................................192
Steering Pilot Valve - NO TURN .................................................................................193
Steering Pilot Valve - RIGHT TURN...........................................................................194
Steering System - HOLD..............................................................................................196
Steering System - GRADUAL LEFT TURN...............................................................197
BRAKE AND HYDRAULIC FAN SYSTEM COMPONENTS.......................................199
Brake and Hydraulic Fan System - CUT IN AND MINIMUM FAN SPEED ............201
Brake and Hydraulic Fan System - MINIMUM FAN SPEED AT CUT OUT ............202
Brake and Hydraulic Fan System - MAXIMUM FAN SPEED AT CUT OUT...........204
Brake and Hydraulic Fan Pump....................................................................................211
Brake and Hydraulic Fan Pump - ENGINE OFF.........................................................212
Brake and Hydraulic Fan Pump - LOW PRESSURE STANDBY ..............................213
Brake and Hydraulic Fan Pump - UPSTROKE ...........................................................215
Brake and Hydraulic Fan Pump - CONSTANT FLOW...............................................216
Brake and Hydraulic Fan Pump - DESTROKE...........................................................217
Brake and Hydraulic Fan Pump - HIGH PRESSURE STALL....................................218
Accumulator Charge Valve and Hydraulic Fan Solenoid.............................................219
Service Brake Valve......................................................................................................221
Brake Hydraulic System - PARKING BRAKE DISENGAGED ................................222
Brake Hydraulic System - SERVICE BRAKES APPLIED.........................................223
Service Brake Valve - NOT ACTIVATED ...................................................................224
Service Brake Valve - ACTIVATED ............................................................................225
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CATERPILLAR MONITORING SYSTEM ......................................................................229
Fuel Level Sender.........................................................................................................230
Hydraulic Oil Temperature Sensor ...............................................................................231
Service Brake Pressure Switch.....................................................................................232
Axle Oil Temperature Sensors......................................................................................233
Differential Pressure Switch in the Right Side Service Bay........................................234
Action Alarm.................................................................................................................236
Fuel Level Indicator......................................................................................................237
Torque Converter Outlet Temperature Sensor..............................................................238
Electrical System ..........................................................................................................239
Engine Tachometer .......................................................................................................241
Axle Oil Cooler System................................................................................................242
CONCLUSION...................................................................................................................247
HYDRAULIC SCHEMATIC COLOR CODE...................................................................248
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NOTES
10/06

INTRODUCTION
This presentation discusses the component locations and systems operation for the 950H, the
962H Wheel Loaders, and IT62H Integrated Toolcarrier. The new C7 engine, the power train,
proportional priority, pressure compensated implement hydraulics, and the steering and braking
system operation will be covered.
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950H AND 962H II WHEEL LOADERS

The 950H, the 962H Wheel Loaders, and the IT62H Integrated Toolcarrier are medium wheel
loaders in the Caterpillar product line. The serial number prefix for the 950H is K5K Aurora
built (N1A Gosselies, J5J Sagami, M1G Brazil), the serial number for the 962H Wheel Loader
is K6K Aurora built (N4A Gosselies, J6J Sagami, M3G Brazil) and the IT62H Integrated
Toolcarrier prefix M5G is being built in Brazil only. The operating weight for the 950H is
approximately 18,300 Kg (40,300 lbs), the operating weight for the 962H is approximately
19,000Kg (41,900 lbs), and the operating weight for the IT962H is approximately 19,400Kg
(42,770 lbs).
The color codes used for hydraulic oil throughout this presentation are:
Red - System or high pressure
Red and White Stripes - 1st Reduced pressure
Red and White Hatched - 2nd Reduced pressure
Orange - Pilot pressure
Blue - Blocked oil
Green - Tank or return oil
Yellow - Active component
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3
Component Location
This illustration shows the basic component locations on the 950H and 962H. The component
locations on the 950H and 962H are basically the same as in the "G" series II Wheel Loaders.
Power for the 950H, 962H Wheel Loaders ,and IT62 Integrated Toolcarrier is supplied by the
C7 ACERT™ engine. Power flows from the engine to the torque converter, to the
Electronic Clutch Pressure Controlled (ECPC) transmission, through the output transfer gear to
front and rear drive shafts. From the drive shafts, power flows to the bevel gears in the
differentials, and through the axles.
The wheel loader is equipped with a steering pump, a steering valve, and the steering cylinders.
Also, the machine is equipped with an electrohydraulic implement control with a variable
displacement implement piston pump supplying oil to the 3PC hydraulic valve located in the
loader frame.
The machine maybe equipped with an optional electric steering pump that is installed inside the
rear frame. This pump supplies oil to the steering system with a loss of main steering supply
oil.
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C7
Engine
Transmission
Front
Final Drive
Rear
Final Drive
Rear
Drive Shaft
Torque
Converter
Front
Drive Shaft
Parking
Brake
Hydraulic
Tank
Engine
ECM
Radiator
and ATAAC
Implement
Control Valve
Tilt
Cylinder
Lift
Cylinder
Tilt Position
Sensor
Lift
Position
Sensor
Implement
Control Levers
Fan Pump
Power Train and
Implement ECM
Steering
Valve
Implement and
Steering Pumps
Fan
Motor
Steering
Cylinder
Air Conditioner
Condenser
Hydraulic Fan
Cooler
Accumulator
Charging Valve
Steering Control
Valve
WHEEL LOADER COMPONENTS
Electrical Components Hydraulic Components Power Train ComponentsEngine Components

The wheel loader is equipped with an on demand hydraulic fan system and brake system. The
systems share a common variable displacement piston pump and accumulator charging valve.
The charging valve gives priority to the brake system over the hydraulic fan system. The brake
system includes the front and rear service brakes with a hydraulic release parking brake.
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ENGINE
The C7 ACERT™ engines utilize the A4 Electronic Control Module (ECM) engine control and
is equipped with an Air-to-Air Aftercooler (ATAAC) intake air cooling system. The C7 engine
is an in-line six-cylinder arrangement with a displacement of 7.2 L. The C7 engine in the 950H
is rated at 147 kW (197 net horsepower). The C7 engine in the 962H and the IT62H is rated at
157 kw (211 net horsepower). The C7 engines are electronically configured to provide constant
net horsepower through the operating ranges. Constant net horsepower automatically
compensates for any parasitic loads, allowing the operator to maintain a constant level of
productivity.
C7 ACERT™ Technology provides an advanced electronic control, a precision fuel delivery,
and refined air management.
The Engine ECM utilizes the Advanced Diesel Engine Management (ADEM IV) to control the
fuel injector solenoids and to monitor fuel injection. The fuel is delivered through a Hydraulic
Electric Unit Injection (HEUI) system.
The C7 ACERT™ is equipped with a wastegate turbocharger which provides higher boost over
a wide range, improving engine response and peak torque, as well as outstanding low-end
performance.
The C7 ACERT™ engines meet US Environmental Protection Agency (EPA) Tier III Emission
Regulations for North America and Stage IIIa European Emission Regulations.
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5
Engine Electrical Block Diagram
This block diagram of the engine electrical system shows the components that are mounted on
the engine which provide input signals to and receive output signals from the Engine Electronic
Control Module (ECM).
Based on the input signals, the Engine ECM energizes the injector solenoid valves to control
fuel delivery to the engine, and the cooling fan proportional solenoid valve to adjust pressure to
the cooling fan clutch.
The two machine interface connectors provide electrical connections from the engine to the
machine including the Cat Data Link.
Some of the components connected to the Engine ECM through the machine interface
connectors are: the throttle pedal position sensor, the ether aid solenoid, and the ground level
shutdown switch.
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Primary Speed Timing Sensor
Caterpillar Monitor
SystemEngine ECM
+ 5 Volt (Sensors)
Atmospheric Pressure Sensor
Intake Manifold Pressure Sensor
Cat Data Link
INPUT COMPONENTS
C7 ENGINE
ELECTRICAL SYSTEM
Intake Manifold Temperature Sensor
Ground Level Shutdown Switch
Throttle Pedal Position Sensor
Fuel Differential Pressure Switch
Auto Reversing
Fan Solenoid Valve
Key Start Switch ON (B+)
Demand Fan Solenoid
Valve
OUTPUT COMPONENTS
Coolant Temperature Sensor
Engine Oil Pressure Sensor
Turbo Inlet Pressure Sensor
Intake Air Heater Relay
Air Filter
Restricted Indicator
Intake Air Heater Indicator
Auto Reversing Fan Switch
Throttle Sensor Voltage
Analog Sensor Voltage
6 Hydraulic Electronic
Unit Injectors
Secondary Speed Timing Sensor
Injection Actuation Pressure Sensor
Injection Actuation
Pressure Solenoid
Ether Aid Solenoid

Input Components:
Atmospheric pressure sensor - This sensor is an input to the Engine ECM and is used as a
reference for air filter restriction. Also, the sensor is used to supply information to the Engine
ECM during operation at high altitude.
Turbo inlet pressure sensor - This sensor is an input to the Engine ECM to supply
information about the air restriction before the turbocharger.
Intake manifold temperature sensor - This sensor is an input to the Engine ECM to supply
information about the air temperature entering the intake manifold from the ATAAC.
Intake manifold pressure sensor - This sensor is an input to the Engine ECM supplying
information about air pressure (boost) in the intake manifold.
Fuel differential pressure switch - This switch relays information to the ECM that the fuel
pressure at the output of the filter base is restricted in comparison to the inlet pressure.
Coolant temperature sensor - This sensor is an input to the Engine ECM supplying
information on the temperature of the engine coolant. The ECM uses this information for
demand fan solenoid current, high coolant temperature warnings, engine derates for high
coolant temperature, or logged events.
Engine oil pressure sensor - This sensor is an input to the Engine ECM to supplying
information on engine oil pressure. The ECM uses this information for low oil pressure
warnings,.engine derates for low oil pressure, or logged events.
Throttle pedal position sensor - This sensor sends a PM signal to the Engine ECM with the
amount of movement of the governor pedal. This signal is used to increase or decrease the
amount of fuel by the injectors.
Auto reversing fan switch - This switch is an operator input to the Engine ECM. The operator
can manually enable the reversing solenoid valve and change the direction of oil flow through
the hydraulic fan motor .
Ground level shutdown switch - This switch is an input to the Engine ECM. This input
disables fuel injection when the engine is running or at engine start-up.
Primary and secondary speed timing calibration sensor - These speed sensors are passive
speed sensors that provide a signal similar to a sine wave that varies in amplitude and
frequency as speed increases. The permanent timing calibration sensor monitors the speed and
position of the flywheel.
Key switch ON (+B) - The Key On input to the Engine ECM enables the ECM for operation
and allows the Engine ECM to be recognized by any ECM on the machine.
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Injection activation pressure sensor - This sensor sends the rail oil pressure feedback data to
the Engine ECM.
Output Components:
+5 Volt - Regulated supply voltage for the sensor inputs to the Engine ECM.
Throttle sensor voltage - Voltage supply for the throttle position sensor.
Analog sensor voltage - Analog voltage for the Turbo inlet pressure sensor.
Intake air heater relay - The start aid relay sends current to the air intake heater to warm the
air in the intake manifold for starting the engine in cold weather conditions.
Auto reversing fan solenoid valve - This solenoid valve is used in order to reverse the oil flow
oil through the hydraulic fan motor..
Demand fan solenoid valve - Proportional solenoid valve that controls the signal pressure to
the brake and fan pump in order to meet the varying cooling requirements of the machine.
Air filter restriction indicator ON - This indicator illuminates in case of a restriction in the
inlet air system.
Intake air heater indicator ON - This indicator illuminates when the air heater relay is
energized.
Injection actuation pressure solenoid - This solenoid electronically controls the high pressure
HEUI pump output. This solenoid is confined inside the pump control.
Mechanical electronic unit injectors (6) - Injectors supply a governed amount of fuel to the
basic engine.
Ether aid solenoid - This solenoid is energized when the Engine ECM recognizes that the
either the engine coolant temperature or the intake manifold air temperature is below
-9 °C (16 °F).
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Speed/Timing Sensors
The primary speed timing sensor (1) and secondary speed timing sensor (2) are located below
the Hydraulic Electronic Unit Injector (HEUI) and above the hydraulic fan pump (3). Under
normal operation, the primary speed timing sensor (1) determines the No. 1 compression timing
prior to the engine starting. If the primary speed timing sensor is lost, a CID 190 MID 08
primary engine speed signals abnormal and the secondary sensor will time the engine with an
extended starting period and run rough until the Engine ECM determines the proper firing order
using the secondary speed timing sensor only. If the secondary speed timing sensor is lost, a
CID 342 MID 08 secondary engine speed signals abnormal and the primary sensor will time the
engine with an extended starting period and run rough until the Engine ECM determines the
proper firing order using the secondary speed timing sensor.
In the case that the signal from both engine speed sensors are lost, the engine will not start.
During a running condition, the engine will shutdown.
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1
3

7
Engine Speed/Timing Calibration Port
The speed/timing calibration port (1) is located on the right side of the machine. Remove the
plug in order to install the timing probe. The Engine ECM (2) has the ability to calibrate the
mechanical differences between the Top Center (TC) of the crankshaft and the timing gear on
the camshaft. A magnetic transducer signals the TC of the crankshaft to the ECM when the
notch (not shown) on a counterweight passes by the transducer (not shown). The speed/timing
sensor signals the TC of the timing gear to the Engine ECM. Any offset between the TC of the
crankshaft and the TC of the timing gear is stored into the memory of the Engine ECM.
NOTE: For additional information in troubleshooting the engine, refer to the Service
Manual module Troubleshooting "C7 Engines for Caterpillar Built Machines"
(RENR9319) "Engine Speed/Timing Sensor - Calibrate.”
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1 2

8
Fuel System
Fuel is drawn from the fuel tank through the primary fuel filter (10-micron) and water separator
through the Engine ECM (for cooling purposes) by a gear-type fuel transfer pump. The fuel
transfer pump then pushes the fuel through the secondary fuel filter (2-micron). The fuel then
flows to the cylinder head. The fuel enters the cylinder head and flows into the fuel gallery,
where it is made available to each of the six HEUI fuel injectors. Any excess fuel not injected
leaves the cylinder head and flows past the fuel pressure regulator returning to the fuel tank.
The fuel pressure regulator is an orifice that is installed at the rear of the cylinder head. The
fuel pressure regulator maintains fuel system pressure between the fuel transfer pump and the
fuel pressure regulator.
From the fuel pressure regulator, the excess fuel flow returns to the fuel tank. The ratio of fuel
used for combustion and fuel returned to tank is approximately 3:1 (i.e. four times the volume
required for combustion is supplied to the system for combustion and injector cooling
purposes).
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Fuel
Transfer Pump
Primary
Fuel Filter /
Water Separator
Secondary
Fuel Filter
Electric Fuel
Priming Pump
Fuel Pressure
Regulator
Fuel Gallery
Fuel Tank
C7 ENGINE
FUEL DELIVERY SYSTEM
(Optional)
Fuel Heater
Engine ECM
HEUI
Pump
Injection
Actuation
Solenoid
High Pressure Engine Oil Pressured FuelEngine Lubrication Oil Return Pilot Oil

A pressure differential switch is installed in the secondary fuel filter base and will alert the
operator of a fuel filter restriction. The pressure differential switch compares the filter inlet
pressure to the filter outlet pressure. When the difference in the inlet and outlet pressures
causes the switch to activate, the Engine ECM will signal the Caterpillar Monitoring System to
warn the operator the fuel flow is probably restricted.
A fuel pressure sensor is installed in the secondary fuel filter base and will signal the Engine
ECM of a high fuel pressure. If the fuel pressure exceeds a pressure of 758 kPa (110 psi) the
Engine ECM will log a E096 code.
The HEUI pump is a variable displacement piston pump that intensifies engine oil pressure and
directs that oil to the individual injectors. The injection actuation solenoid is also contained
inside the HEUI pump. The solenoid is an output directly from the Engine ECM that controls
the amount of oil actuation pressure for the amount of fuel injection.
10/06

Fuel Transfer Pump
The fuel transfer pump (1) is a gear pump that is attached to the Hydraulic Electronic Injector
Unit (HEUI) (2) between the engine and the secondary fuel filter (not shown). The filter
groups are removed for clarity. The fuel transfer pump is also driven by HEUI. Fuel is drawn
from the fuel tank, the primary fuel filter and water separator (not shown), through the Engine
ECM, to the hose (5) by the fuel transfer pump. Then, the fuel is directed to the secondary fuel
filters through the hose (4).
In the high pressure system using the HEUI pump, pressurized oil from the engine lube system
is directed to the pump through hose (7). Then, high pressure engine oil is directed through
tube (6) to the injectors.
Also shown is the connection for the injection actuation solenoid that is located at
connector (3).
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1
2 3 4
5
6
7

10
Power Derate
The illustration above defines the power derate in relation to the rated torque map and the
default torque map. The power derate is a percentage reduction from the rated power at a given
engine speed toward the default map at the same rpm.
The derated power is what has changed, not the actual power in all situations. The actual
power rating lost during a derate is calculated as:
Power_Output = Rated Power - (Rated Power - Default Power) * Percentage of Derate
For example, if the engine has a maximum rated power of 500 hp and a 100 hp default torque
map with a 50% derate, the engine will have 300 hp output power. If 250 hp was needed, then
the operator will not notice any change. If however, 400 hp was needed, there would be only
300 hp available due to a derate.
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50% Derate
100% Derate
Highest Rated Torque Map
Default Torque Map
Power
Engine Speed
POWER DERATE
Derate

The fuel system is equipped with two filters: a primary fuel filter/water separator (4) and a
secondary filter (3).
The primary fuel filter is located on the right side of the machine. The primary filter contains a
water separator which removes water from the fuel. Water in a high pressure fuel system can
cause premature failure of the injector due to corrosion and lack of lubrication. Water should
be drained from the water separator daily, using the drain valve that is located at the bottom of
the filter.
The electric fuel priming pump (5) is integrated into the primary fuel filter base. The priming
pump is activated by toggling the fuel priming pump switch (6). The fuel priming pump is
used to fill the fuel filters with fuel after they have been replaced.
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1 2
3
4
5
6

The priming pump will purge the air from the entire fuel system. To activate the fuel priming
pump, the key start switch must be in the OFF position.
The fuel system is equipped with a secondary high efficiency fuel filter. Also, installed on the
base is a fuel pressure differential switch (1), and a fuel pressure sensor (2).
The fuel differential pressure switch monitors the difference between the outlet fuel pressure
and the inlet pressure. When the fuel differential pressure exceeds 103 kPa (15 psi) a Level 1
Warning will be initiated. Then, after 4 hours the Engine ECM initiates a Level 2 Warning and
an Engine Derate.
The fuel pressure sensor is used to indicate low fuel pressure. With the C7 HEUI engine, low
fuel pressure initiates a low fuel pressure derate of 50%. The Engine ECM limits the rail oil
pressure because large fueling values will cause late combustion cycles, which results in
excessive smoke and possible engine damage. Also, at startup and after 10 seconds, with low
fuel pressure a 94-11 event is logged. The reason for this event is to detect situations where the
fuel has drained out of the rail and is taking excessive time to reach the required pressure.
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13
High Fuel Filter Restriction Derates
When the differential pressure switch recognizes a fuel pressure of 103 kPa (15 psi) for 3
minutes, the Engine ECM will initiate a Level 1 Warning.
When the differential pressure switch recognizes 15 psi across the filter for 4 hours, the Engine
ECM will initiate a Level 2 Warning. With the Level 2 Warning initiated a 17.5 % derate is
applied to the engine. After 1 second, the Engine ECM will initiate a second derate of 17.5%.
The total derate will be 35%.
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0 3 min 3 hr
60%
50%
40%
30%
20%
10%
0%
%Derate
1 hr 2 hr 5 hr4hr
1 sec
4 hr
Time
Level 1Warning Level 2 Warning / Derates
FUEL FILTER RESTRICTION DERATE
AND PRESSURE ABOVE 103 kPa (14 psi)

14
The illustration shows a top view of the engine. The Injection Actuation Pressure (IAP) sensor
located in the top of the engine block measures the hydraulic actuation pressure and sends the
actual oil pressure to the Engine ECM. The ECM compares the desired pressure to the actual
pressure in order to figure the proper amount of oil pressure to be sent to the injectors.
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Engine Inlet Air System
In the engine inlet air system, the air enters the compressor section of the turbocharger (4)
through the air cleaner (2). The compressor directs the air through the ATAAC (3), the air
intake manifold, and to the cylinder head.
Exhaust exits the cylinder head to the turbine housing. From the turbine housing, the turbine
wheel directs the exhaust out of the Turbo and out through the muffler (1).
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3
3
4

17
The C7 ACERT™ engines are equipped with a wastegate turbocharger which provides higher
boost over a wide range, improving engine response and peak torque, as well as outstanding
low end performance. All of the exhaust gases go from the exhaust manifold through the
turbocharger.
The exhaust gases enter the turbocharger and drive the turbine wheel. The exhaust exits the
turbocharger through turbine wheel outlet (2) to the muffler. The turbine wheel is connected by
a shaft to the compressor wheel. The turbine wheel rotates the compressor wheel at very high
speeds. The rotation of the compressor wheel pulls clean air through the compressor housing
air inlet (1). The compressor wheel blades force air into the cylinder head to the inlet valves.
The increased amount of forced air enables the engine to burn more fuel, producing increased
power. The engine can operate under low boost conditions. During a lower boost condition,
the canister closes the wastegate, allowing the turbocharger to operate at maximum
performance. Under high boost conditions, the wastegate opens. The open wastegate allows
exhaust gases to bypass the turbine side of the turbocharger. The rpm of the turbocharger is
limited by bypassing a portion of the exhaust gases around the turbine wheel of the
turbocharger.
NOTE: The wastegate calibration is preset at the factory.
10/06
1 2

18
Turbo Inlet Pressure Sensor
The turbocharger inlet pressure sensor (1) is located in the tube that is between the air filter
group (2) and the inlet to the compressor housing of the turbocharger.
The turbocharger inlet pressure sensor measures restriction of air flow through the air filter
group and the inlet to the turbocharger. Restriction of the air flow to the turbocharger will
initiate a warning and engine derate.
10/06
1
2

19
Air Inlet Restriction Derate
The turbo inlet pressure sensor measures the restriction of the air inlet that is flowing to the
inlet of the compressor housing of the turbocharger. When the pressure difference between the
Turbo inlet pressure sensor and the atmospheric sensor read a difference of 9.0 kPa, the
Engine ECM will derate the engine approximately 2%. The Engine ECM will then derate the
engine 2% more for every 1 kPa difference up to 10%.
Typically the atmospheric (barometric) pressure sensor is 100 kPa at sea level. As the air
restriction increases, the difference will increase. The first derate will occur when the
difference is approximately (100 kpa minus 91 kPa.= 9 kPa). If the air inlet restriction is 92.5
kPa (a pressure that is between 7.5 kPa and 9 kPa) for 10 seconds, the Engine ECM will initiate
a Level 1 Warning.
If the air restriction goes to the point that the turbo inlet pressure sensor sees a difference of
91.0 kPa (a pressure that is 9.0 KPa) for 10 seconds, then the Level 2 Warning will occur, and
the engine will derate.
NOTE: This air inlet restriction derate is a latching derate. The derate will remain
active until the machine is shut down.
10/06
0 2 4 6 8 10
12%
10%
8%
6%
4%
2%
0%
%Derate
12 14 16
14%
16%
Air Restriction kPa Difference
AIR INLET RESTRICTION DERATE

20
Engine Oil Pressure Sensor
The engine oil pressure sensor (1) is located on the left side of the engine and the right side of
the machine near the Engine ECM (2). The sensor monitors the pressure of the engine oil.
The engine oil pressure sensor is one of the many sensors that require a regulated 5.0 VDC for
the sensor supply voltage. The sensor outputs a variable DC voltage signal.
The Engine ECM will use the information supplied oil pressure sensor to output warning levels
to the Caterpillar Monitoring System and engine derates.
10/06
2
1

21
Low Oil Pressure Derate
This illustration shows a graph with the two different warning levels for low oil pressure.
When the oil pressure is below (154 kPag @ 1600 rpm) the blue line, the cat monitoring system
will enable the low oil pressure Level 1 Warning. Change machine operation or perform
maintenance to the system.
When the oil pressure is below (104 kPag @ 1600 rpm) the red line, the cat monitoring system
will enable the low oil pressure Level 3 Warning. The operator should immediately perform a
safe engine shutdown.
Also, with the Level 3 Warning, the Engine ECM initiates a 35% engine derate.
If the signal between the Engine ECM and the oil pressure sensor is lost or disabled, the Engine
ECM will initiate a low engine oil pressure Level 1 Warning.
10/06
500
120
100
80
60
40
20
0
OilPressure(kPa)
1000 1500 2000 2340
140
160
180
35% Derate
0 Derate
0
Engine rpm
kPa Warning Level 1 kPa Shutdown Level 3
LOW OIL PRESSURE
35% Derate

22
Coolant Temperature Sensor
The coolant temperature sensor (1) is installed on the engine block behind the primary fuel
filter and water separator. The primary fuel filter and water separator is transparent to show the
location of the component. The coolant temperature sensor monitors the temperature of the
fluid in the coolant system. The coolant sensor information sent to the Engine ECM is used for
Warning Levels that are sent to the Caterpillar Monitoring System and engine derates.
10/06
1
2
3

23
High Coolant Temperature Derate
The coolant temperature sensor measures the temperature of the coolant.
When the temperature of the coolant exceeds 108° C (226° F), the Engine ECM will initiate a
Level 1 Warning.
When the temperature of the coolant exceeds 111° C (231° F), the Engine ECM will initiate a
Level 2 Warning. At 111° C (231° F) the Engine ECM will initiate a 25% derate. Refer to the
illustration above for the remainder of the high engine coolant temperature derates. At 100%
derate, the engine available power will be approximately 50%.
10/06
108 111 111.5 112 112.5 113 113.5 114
120%
100%
80%
60%
40%
20%
0%
Coolant Temperature ° C
%Derate
HIGH COOLANT TEMPERATURE DERATE
114.5

Intake Manifold Sensors
The upper illustration shows the intake manifold temperature sensor (1).
The intake manifold temperature sensor (1) is used to monitor the air temperature flowing into
the intake manifold. The intake manifold pressure sensor (3) is used to monitor the air pressure
in the intake manifold. The Engine ECM (5) also uses the temperature sensor as one of the key
target temperatures to control the fan speed in the hydraulic fan system and as an input to the
Engine ECM for the virtual exhaust temperature derate. Also shown is the primary fuel filter
and water separator (4).
24
25
10/06
1
1 3
4
2
5

The atmospheric pressure sensor (2) is located on the right side of the machine on the engine.
The Engine ECM uses the sensor as a reference for air filter restriction, and derating the engine
under certain parameters. All pressure sensors in the system measure absolute pressure and,
therefore, require the atmospheric (barometric) pressure sensor to calculate gauge pressures.
The atmospheric pressure sensor is one of the many sensors that require a regulated 5.0 VDC
for the sensor supply voltage. The atmospheric pressure sensor outputs a variable DC voltage
signal.
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26
Intake Manifold Air Temperature Sensor Derate
The intake manifold air temperature sensor measures the temperature of the air that is flowing
to the intake manifold. The sensor is used to initiate warning levels in the Caterpillar
Monitoring System and engine derates for the C7 ACERT™ Engine.
After the engine is running for at least 3 minutes and if the intake manifold air temperature goes
above 90° C (194° F), the Engine ECM will initiate a Level 1 Warning.
After the engine is running for at least 3 minutes and if the intake manifold air temperature goes
above 110° C (230° F), the Engine ECM will initiate a Level 2 Warning. With the Level 2
Warning, the Engine ECM signals the engine to initiate a 3% derate. This derate will have a
20% upper limit.
10/06
90° 110° 111° 112° 113° 114° 115° 116°
18%
15%
12%
9%
6%
3%
0%
Intake Manifold Temperature ° C
%Derate
117°
21%
Level 1Warning
C7 INTAKE MANIFOLD AIR TEMPERATURE DERATE
Level 2 Warning / Derates

27
Virtual Exhaust Temperature Derate
An engine derate can occur due to a estimated (virtual) high exhaust gas temperature. The
Engine ECM monitors barometric pressure, intake manifold temperature, and engine speed to
estimate exhaust gas temperature. Certain conditions (high altitude, high ambient temperatures,
high load and full accelerator pedal throttle, barometric pressure, intake manifold temperature,
and engine speed) are monitored to determine if the engine derate should be enabled. The
Engine ECM determines a maximum fuel delivery percentage to maintain safe maximum power
output under load. This calculation is new to the off-road Tier III engines and is used in place
of the previous altitude compensation derate strategy.
This event is to inform the mechanic that a derate has occurred because of operating conditions.
Generally, this is normal and requires no service action.
The Engine ECM will process all derate inputs in the highest derate priority selector. The most
critical derate condition input will be used to adjust fuel system delivery limiting engine power
to a safe level for the conditions in which the product is being operated, there by preventing
elevated exhaust temperatures.
10/06
Engine ECM
Barometric Pressure
Inlet Manifold Temperature
Engine Speed
Engine Derate
Percentage
Other Engine
Derate
Conditions
VIRTUAL EXHAUST TEMPERATURE DERATE
Fuel Injection
Calibration
Highest Derate
Priority
Selector

The virtual exhaust temperature derate will log a 194 event code. The derate will enable a
Level 1 Warning and eventually a Level 2 Warning. The level of the warning will depend on
the conditions that are sent to the Engine ECM.
The following conditions must be met in order to initiate a virtual exhaust temperature derate.
- No CID 168 01 FMI (low battery voltage to the Engine ECM) are active.
- No active intake manifold pressure sensor faults.
- No active atmospheric pressure (barometric) sensor faults.
- No +5 V sensor voltage codes active.
- The virtual exhaust temperature derate must be the highest derate.
- More fuel is being requested than the virtual exhaust temperature derate will allow.
This derate is triggered by the information inferred by the Engine ECM, rather than an
individual sensor as with the previous single derate strategies. If you think this derate is
possibly being imposed incorrectly check for event codes on the high intake manifold
temperature and correct those first. Also, make sure the aftercooler is unobstructed. For
additional information about troubleshooting, refer to the troubleshooting manual for the
particular engine that is being serviced.
10/06

The intake manifold air heater (1) is located in the intake manifold and the relay (2) is located
on a bracket behind the fuel filter and water separator. The Engine ECM receives temperature
data from both the intake manifold air temperature and coolant temperature sensors to control
energizing of the heater relay. If the altitude is above 1675 m (5500 ft) use the high altitude
coolant and intake manifold air temperature. The high altitude heater control temperatures is
53.3° C (127° F).
The intake manifold air heater has the following five cycles.
1. The first cycle is the power-up. The heater and the indicator lamp are energized for two
seconds at power-up regardless of the temperature.
2. The second cycle is the pre-heat. The heater and indicator lamp will be energized to 30
seconds if the coolant and/or air temperatures are below 25° C (77° F). After 30 seconds,
the heater and indicator lamp are turned OFF if the engine speed is at 0 rpm.
3. The third is the crank cycle. The heater and indicator lamp will be ON continuously if
the coolant and/or air temperature is below 25° C (77° F) as long as the engine is being
cranked.
4. The forth is the engine running cycle. Once the engine is at low idle and the coolant
and/or air temperature is below 25° C (77° F), the heater and indicator lamp are
energized to an additional 7 minutes.
5. The fifth is the post-heat cycle. If the coolant and/or air temperatures are below 25° C
(77° F) the heater and lamp are cycled ON and OFF for an additional 13 minutes. The
cycle is ten seconds ON and then 10 seconds OFF.
Also shown is the Injection Actuation Pressure (IAP) sensor (3).
28
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1
2
3

29
The left side of the front dash panel shows the AIR FILTER RESTRICTED condition. The
illuminated indicator is enabled by an output from the Engine ECM through the Cat Monitoring
System.
The right side of the front dash panel shows the intake air heater ON condition. The
illuminated indicator is also enabled by an output from the Engine ECM through the Cat
Monitoring System.
10/06
LEFT SIDE PANEL RIGHT SIDE PANEL

The ether aid system is an attachment on the 950H, the 962H Wheel Loaders, and the IT62H
Integrated Toolcarrier. This attachment may be added for engine starts in cooler ambient
temperatures. The ether aid system consists of the following components:
- Ether aid bottle (1)
- Ether aid solenoid (2)
- Ether aid connector installed on the intake manifold (3)
30
31
10/06
1
2
3

When the machine is operated in a cold ambient environment, ether may be installed along
with the intake manifold air heater to start the engine. In order to use the ether aid, the ether
aid system must be installed in the engine compartment and the ether aid must be enabled
through Caterpillar Electronic Technician (ET).
For the engines in the 950H, 962H wheel loaders, and the IT62H Integrated Toolcarrier, the
cold start strategy is dependent on whether the intake manifold air temperature or the engine
coolant temperature registers as the lower temperature. The Engine ECM looks at the lowest
temperature between the two sensors and that information registers into the temperature map.
The ECM compares the temperature map against the atmospheric pressure sensor and decides
whether ether is required to start the engine.
If either temperature is below -9° C (15° F) continuous metered ether injection is sent to the
intake manifold at connector (3). If the temperature is above -9° C (15° F), the intake manifold
air heater is enabled.
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32
Engine Idle Management System (EIMS)
Engine Idle Management System (EIMS) sets the engine idle to maximize fuel efficiency.
Also, this system uses new and improved software to benefit the customer with reduced sound
levels, reduced emissions, machine ability to set machine parameters to the working conditions,
machine ability to set machine to working applications, and increased battery durability.
Work Mode - This mode allows the working idle to be programmed according to the customer's
applications requirements. The work mode idle can be adjusted to a higher or lower rpm
through Caterpillar Electronic Technician (ET). The engine idle range is between 650 rpm and
1000 rpm. In order to go into the work mode, the percentage of fan bypass must be less than
23%.
Warm up Mode - In a cold weather operation, the default engine rpm will be set to 1100 rpm in
order to generate additional engine heat, keeping the engine warmer. This mode monitors the
coolant temperature and intake manifold temperature. When the coolant temperature is below
80° C (176° F) or the intake manifold temperature is below 15° (60° F) and the warm mode is
enabled, the machine will time out for 10 minutes. After ten minutes, the coolant temperature
is below 70° C (158° F) and the machine has been in the warm up mode, the engine will be in
warm up mode. If the machine has not been in warm up mode but the intake manifold
temperature is less than 5° C (41° F), the engine will go into the warm up mode.
10/06
ENGINE IDLE MANAGEMENT MODES
- Work Mode
- Warm Up Mode
- Hibernate Mode
- Low Voltage Mode

Also, the transmission speed selector must be in the NEUTRAL position, the parking brake
engaged, and the throttle position sensor output less than 5% for the engine to go to the warm
up mode idle.
Hibernate Mode - This mode is initiated only when the transmission speed selector switch is in
the NEUTRAL position, the parking brake is engaged, the throttle position sensor output is less
than 5%, the coolant temperature is above the EIMS default, the fan bypass is above 23%, and
the implement control levers are not activated. When these parameters are met along with a 10
second period after the parking brake is engaged, the hibernate mode will lower the engine idle
to 600 rpm. The engine will idle at 600 rpm until one of the above parameters are no longer
met.
Low Voltage Mode - In this mode, the engine idle will ramp up to 1100 rpm when the battery
voltage drops below 24.5 VDC and he engine has been running for 5 minutes. The low voltage
mode feature is standard on all machines with EIMS with high current drain due to heavy
electrical loads from custom attachments. When the battery voltage is greater than 24.5 VDC,
the engine idle will return to the current working low idle speed. The 24.5 battery voltage is a
default and can not be reconfigured in ET.
10/06

33
POWER TRAIN
This illustration shows the major components in the power train.
Power from the engine flows to a 360 mm (14.5 inch) diameter torque converter. The torque
converter output shaft is splined to the input shaft of the electronically controlled power shift
transmission.
The transmission output shaft is splined to the output transfer gear. The output transfer gear
transmits power from the transmission to the front and rear drive shafts.
Power from the transmission output shaft flows through the front drive shaft and the parking
brake to the front pinion, bevel gear, differential and axles to the final drives.
Power from the transmission output shaft also flows through the rear universal joint group to
the rear pinion, bevel gear, differential and axles to the final drives.
Power train movements and operations are controlled through the Power Train ECM.
10/06
ACERT
Engine
Output Transfer
Gear Case
Front
Final Drive
Rear
Final Drive
Rear
Drive Shaft
Torque
Converter
Transmission and
Modulating Valves
Front
Drive Shaft
Parking
Brake
Power Train
ECM
Upshift, Downshift
Direction Switches
POWER TRAIN COMPONENTS

34
Power Train Electrical System
This illustration shows the input components which provide power or signals to the Power
Train ECM.
Power Train ECM Inputs:
Shift lever upshift, downshift, forward, neutral, reverse: Combines control of the
transmission shifting to a single input device. The shift lever can be pushed forward, backward,
or placed in the middle position for machine direction. The lever is rotated in order to change
the speeds of the transmission. This is the standard control for shifting that comes with the
Hand Metering Unit (HMU) steering.
Direction switch forward, neutral, reverse, upshift, and downshift: Combines control of the
transmission shifting with a single input device. The 3 position rocker switch controls direction
and the 2 thumb switches control upshift and downshift. This is the control for shifting that
comes with the Command Control Steering (CCS).
Key start switch: Provides a signal to the Power Train ECM when the operator wants to start
the engine. The direction switch/shift lever must be in the NEUTRAL position before the
Power Train ECM will permit engine starting.
10/06
Transmission Output
Speed Sensor 1 and 2
Power Train ECM
Variable Shift Control
Selector Switch
Parking Brake
Pressure Switch
Left Brake
Pedal Position Sensor
Shift Lever
Upshift, Downshift,
Forward, Neutral,
Reverse
Key Start Switch
Cat Data Link
INPUT COMPONENTS
Auto / Manual Speed
Selector Switch (CCS Option)
Primary Steering
Pressure Switch
Secondary Steering
Pressure Switch
Torque Converter
Output Speed Sensor
Ride Control Switch
(OFF, SERVICE, AUTO)
Transmission Neutralizer
Disable Switch
Transmission Oil
Temperature Sensor
Location Code 2 (Ground)
+24 Battery Voltage
Location Code
Enable (Ground)
Auto / Manual Speed
Selector Switch (HMU)
Implement Pod
Downshift Switch
Heated Mirror Switch
Secondary Steering
Test Switch
Direction Switch
Forward, Neutral, Reverse,
Upshift, Downshift
(CCS Optional)
Engine Speed (CAN)
POWER TRAIN ELECTRICAL SYSTEM
Caterpillar Monitor
System

Variable shift control selector switch: The variable shift control switch is an input of the
Power Train ECM. The switch allows the selection of a range of shifting points in the Power
Train ECM for each speed. The switch has three inputs to the Power Train ECM.
Transmission output speed sensors 1 and 2: These sensors measure the transmission output
speed in the range of 25 to 3000 rpm. By looking at the difference in phase in between these 2
sensors, direction can be derived.
Torque converter output speed sensor: Measures the torque converter speed in the range of
25 to 3000 rpm.
Auto/manual speed selector switch (HMU): Signals the Power Train ECM which shift mode
the operator wants to operate on a standard machine. The operator can select between manual
shifting or automatic shifting in the range of gears 4 to 2 or in the range of gears 4 to 1.
Maximum gear, if lower gear than 4 is desired, will be determined by the shift lever position.
Auto/manual Speed selector switch (CCS option): Signals the Power Train ECM which shift
mode the operator wants to operate on a machine with the optional Command Control Steering.
The operator can select between manual shifting and automatic shifting with maximum gear of
4, 3 or 2 and also a 4 to 1 range shifting mode.
Primary steering pressure switch: Sends a signals the Power Train ECM if the steering
system loses steering pressure.
Secondary steering pressure switch: The switch informs the Power Train ECM that the
secondary steering pump is correctly building up pressure. The switch is used as feedback for
the startup test and the manual switch test to ensure that the Secondary steering system is
operating properly.
Left brake pedal position sensor: Signals the position of the torque converter pedal to the
Power Train ECM. The position of the pedal is being used to downshift the transmission and
neutralize the transmission during operation. Both the downshifting and neutralization function
of the pedal can be disabled and hence the pedal would function as a brake pedal only
Parking brake pressure switch: Provides a signal to the Power Train ECM when the pressure
is adequate to release the parking brake.
Ride control switch (OFF, SERVICE, AUTO): Signals the Power Train ECM which mode
the operator wants to operate. The operator should never operate in SERVICE mode. This
mode is for service only.
Secondary steering test switch: Provides an input to the Power Train ECM that will enable
the secondary steering pump.
Transmission neutralizer disable switch: Provides an input to the Power Train ECM that will
disable the the left pedal neutralization of the transmission.
10/06

Heated mirror switch: Provides an input to the Power Train ECM that will enable the heated
mirror attachment (if equipped).
Transmission oil temperature sensor: Provides an input to the Power Train ECM with the
temperature of the transmission oil.
Implement pod downshift switch: The downshift switch provides an input to the Power Train
ECM to downshift the transmission. This switch is only used on a HMU steering machine.
Engine speed: The Power Train ECM receives the engine speed over the CAN Data Link
from the Engine ECM.
Location code enable (grounded): The location code enable is a grounded input signal to the
Power Train ECM that enables the location code detection feature to become active. J1-32 pin
on the Power Train ECM connector is connected.
Location code 2 (grounded) : The location code pin number 2 is a grounded input signal that
establishes the ECM is dedicated to the Power Train operation. J1-27 pin on the Power Train
ECM connector is connected.
+24 battery voltage: Unswitched power supplied to the Power Train ECM from the battery.
10/06

The Power Train Electronic Control Module (ECM) (arrow) is the central component in the
electronic control system. The ECM is located at the right rear of the cab. The rear panel must
be removed for access to the ECM. The Power Train ECM will be located behind the
operator’s seat and have the connectors horizontal to each other.
The ECM makes decisions based on switch-type and sensor input signals and memory
information. Input signals to the ECM come from the operator's station, the machine, and the
transmission.
The operator's station input components consist of direction and shift switches, the neutralizer
and neutralizer override switches, the park brake switch, the key start switch, and the
auto/manual select switch. Optional switch inputs are the ride control switch and the secondary
steer test switch.
The machine input components are the engine speed sensor, the primary steering pressure
switch, the optional secondary steering pressure switch, and the Caterpillar Monitoring System
message center module.
The transmission input components are the transmission oil temperature sensor, the torque
converter output speed sensor, and the two transmission output speed sensors.
The ECM communicates with other electronic control modules, such as the Caterpillar
Monitoring System, the Engine Electronic Control Module (ECM), and the Electrohydraulic
Electronic Control Module (ECM), through the Cat Data Link. The Cat Data Link allows the
transmission ECM to receive and send information.
35
10/06

The power train and the implement use the same A4M1 Electronic Control Module (ECM). To
enable the A4M1 Electronic Control Module ECM for power train functions, contact (J1-27) is
grounded. Contact (J1-32) is grounded in order to enable the ECM.
The Power Train ECM responds to machine control decisions by sending a signal to the
appropriate circuit which initiates an action. For example, the operator selects an upshift with
the shift lever. The Power Train ECM interprets the input signals from the shift lever, evaluates
the current machine operating status, and energizes the appropriate modulating valve.
The Power Train ECM receives three different types of input signals:
1. Switch input: Provides the signal line to battery, ground, or open.
2. PM input: Provides the signal line with a square wave of a specific frequency and a
varying positive duty cycle.
3. Speed signal: Provides the signal line with either a repeating, fixed voltage level pattern
signal or a sine wave of varying level and frequency.
The Power Train ECM has three types of output drivers:
1. ON/OFF driver: Provides the output device with a signal level of +Battery voltage
(ON) or less than one Volt (OFF).
2. PM solenoid driver: Provides the output device with a square wave of fixed frequency
and a varying positive duty cycle.
3. Controlled current output driver: The ECM will energize the solenoid with 1.25 amps
for approximately one half second and then decrease the level to 0.8 amps for the
duration of the on time. The initial higher amperage gives the actuator rapid response
and the decreased level is sufficient to hold the solenoid in the correct position. An
added benefit is an increase in the life of the solenoid.
The Power Train ECM controls the transmission speed and directional clutches. The Power
Train ECM interprets signals from the shift lever to signal the transmission to perform the
following options: Upshift, Downshift, Forward, Neutral, and Reverse.
The Power Train ECM communicates through the CAT Data Link. The CAT Data Link allows
high speed proprietary serial communications over a twisted pair of wires. The CAT Data Link
allows different systems on the machine to communicate with each other and also with service
tools such as Caterpillar Electronic Technician (ETC).
The Power Train ECM has built-in diagnostic capabilities. As the Power Train ECM detects
fault conditions in the power train system, it logs the faults in memory and displays them
through the Caterpillar Monitoring System.
10/06

Engine Start Switch and Diagnostic Service Tool Connector
The engine key start switch (1) signals the Power Train ECM that the operator wants to start the
engine. The ECM determines if the transmission directional switch (not shown) is in the
NEUTRAL position. When the directional switch is in the NEUTRAL position and the key
start switch (1) is turned to the START position, the ECM energizes the starter relay.
The diagnostic service tool connector (2) for a laptop computer using Caterpillar Electronic
Technician (ETC) is on the front panel on the right side.
A laptop computer with ETC can be used for calibrating, checking and clearing fault codes, and
monitoring system inputs and outputs for troubleshooting the transmission system.
Also shown are the the hazard switch (3), and the 12 Volt adapter socket (4).
36
10/06
1
2
4
3

Transmission Shift Lever
This is an illustration of the standard type of transmission shift lever control group that is found
on the 950H/962H Wheel Loaders. This control group is found on machines with conventional
(HMU) steering systems.
The shift lever is mounted on the left side of the steering column (arrow). The operator moves
the shift lever forward to travel in the FORWARD direction or toward the rear to travel in the
REVERSE direction.
FIRST through FOURTH speeds are selected by rotating the shift lever.
When the transmission is in the Manual mode, the transmission ECM allows the shift lever to
control the transmission. The transmission ECM shifts the transmission to the exact gear and
direction shown on the shift lever.
When the transmission is in the Automatic mode, the shift lever selection is the maximum gear
the transmission will obtain. The transmission ECM will automatically select the correct speed
clutches (SECOND, THIRD, or FOURTH) based on the engine and transmission output speeds.
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10/06

Transmission Shift Control
This illustration shows the transmission shift control for the optional Command Control
Steering (CCS).
The directional control switch (1), and the upshift/downshift switches (2) are mounted on the
left side of the half moon shaped steering wheel.
The directional control switch is a three-position rocker switch which the operator selects either
FORWARD (toggle forward), NEUTRAL (center position), or REVERSE (toggle backward)
directions. The switch position the operator selects will CLOSE (grounds) that particular
contact while the remaining two contacts are OPEN. Closing a switch contact sends a signal to
the Power Train ECM indicating the direction that is being selected by the operator.
The upshift switch/downshift switches are identical in construction and operation. When the
operator wants to manually shift to a higher or lower gear, the upshift switch or downshift
switch is pressed. Each switch has two input connections at the Power Train ECM. When the
switches are not activated, one connection is closed (grounded) and the other connection is
open. When the operator pushes the upshift or downshift switch, the selected switch
momentarily reverses connections to signal the Power Train ECM to change to the desired
speed.
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10/06
1
2

This illustration shows the location of the ride control ON/OFF/AUTO switch (1). The ride
control switch has three positions. In the center position, ride control is disabled. In the UP
position (as shown) the ride control switch is in the AUTO position. With the switch in AUTO,
the ride control system will be enabled when the machine is traveling at least 9.5 km/h (6.0
mph). The SERVICE position (as shown on the switch) is used for service to the ride control
system.
The transmission neutralization disable switch (2) is used to disable the neutralization of the left
brake pedal. Pressing the upper section of the switch will activate the override. When the
neutralization is enabled, the left brake pedal will not neutralize the transmission, but will
function as a service brake only. The normal, default position of the switch is the lower
(released) position
The heated mirror switch (3) enables the heated mirror relay that is located behind the
operator's seat below the Power Train ECM.
If the machine is equipped with the optional secondary steering, there will be a secondary
steering test switch (4) mounted in the blocked position on the panel. When the switch is
depressed it feeds a ground signal to a relay and also to a switch input on the Power Train
ECM. The relay turns on the secondary steering pump motor, which builds up pressure in the
steering hydraulic lines.
The Power Train ECM is monitoring the pressure of the secondary steering hydraulic lines to
ensure the pressure has increased to an acceptable level while the pump is running.
39
10/06
3
21
4

If the switch is depressed and the pressure is not increased to the acceptable level within 3
seconds, the secondary steering warning indicator will be illuminated to indicate that the pump
is not functioning properly.
10/06

The 950H and 962H Wheel Loaders and IT62H Integrated Toolcarrier are equipped with a
variable shift control switch (1). The Power Train (ECM) uses the position of the variable shift
control switch and the engine speed in order to determine the autoshift points for the
transmission. The variable shift control switch has three inputs to the power train electronic
control module (ECM).
The auto/manual gear selector switch (2) sends a signal to the Power Train ECM to control
shifting mode in auto. The Power Train (ECM) shifts the transmission automatically. The
Power Train ECM evaluates the input that is sent from the engine speed sensor, the
transmission speed sensors, the torque converter output speed sensor, and the left brake pedal
position sensor in order to regulate transmission shifts. The automatic mode of operation is
represented by two numbers that are separated by a dash. The first number indicates the speed
of the transmission when the transmission is placed into gear. The second number indicates the
highest speed of the transmission when the machine is travelling.
For example, place the autoshift control switch into the 2-4 position. The machine will
automatically shift into second gear when the transmission is placed into gear. The
transmission will automatically upshift into fourth gear as the machine accelerates.
The Power Train ECM does not allow upshifts to a speed that is higher than the speed that is
selected with the transmission direction and speed control lever. An automatic downshift from
second speed to first speed occurs only if the autoshift switch is in the 1-4 position.
40
10/06
1
2

This illustration shows the panel with the optional Command Control Steering. The
Auto/Manual gear selector switch (arrow) sends a signal to the Power Train ECM to control
shifting mode in auto. In the MANUAL position, the operator is responsible for upshifting and
downshifting the transmission. The Power Train ECM automatically shifts the transmission if
the autoshift switch is in one of the four AUTO positions and the left brake pedal must be
released. The Power Train ECM evaluates the inputs that is sent from the engine speed sensor,
transmission speed sensors, the torque converter output speed sensor, and the left brake pedal
position sensor in order to regulate transmission shifts.
When the machine is operating in "AUTO" mode, the transmission speed selector switch can be
used in order to downshift the transmission. This switch is normally used to downshift from
second speed to first speed in order to load a bucket. The transmission will remain in the
downshifted gear for three seconds after the switch is released. Then, automatic shifting will
resume. If the transmission is downshifted to first speed, the machine remains there until there
is a direction change or a manual upshift.
For example, place the autoshift switch into position "3." The machine will automatically shift
into second gear when the transmission is placed into gear. The transmission will automatically
upshift into third speed when the machine accelerates. An automatic downshift from second
speed to first speed occurs only if the autoshift switch is in the 1-4 position.
The Power Train ECM does not allow automatic upshifts to a speed that is higher than the
speed that is selected with the auto/manual switch. The autoshift switch is used to select the
top speed for the transmission when the transmission is in the AUTO mode. There are four
modes of automatic operation: 4 position, 3 position, 2 position, and 1-4 position.
41
10/06

42
The Power Train ECM receives inputs from three speed sensors on the transmission. The three
speed sensors are:
- the No. 1 output speed sensor (1)
- the No. 2 output speed sensor (2)
- the torque converter output speed sensor (3)
The output speed sensors (1 and 2) are positioned out of phase with each other. The Power
Train ECM uses the phasing of the input data to determine the direction of rotation of the
intermediate and output gears. The torque converter output speed sensor measures torque
converter output speed in the range of 25 to 3000 rpm. The speed sensor information is also
used by the Power Train ECM to set and adjust transmission shift points.
10/06
3
1
2

The Power Train ECM has no direct feed back information to determine if clutch engagement
and disengagement is completed. The Power Train ECM uses the speed sensor information,
including the engine speed sensor data, to measure expected clutch slippage and planetary
speeds to ensure the transmission is shifting according to the application program stored in the
ECM memory.
The torque converter speed sensor (3) sends the torque converter speed to the Power Train
ECM.
A passive (two-wire) magnetic frequency-type sensor converts mechanical motion to an AC
voltage. A typical magnetic pickup consists of a coil, a pole piece, a magnet, and a housing.
The sensor produces a magnetic field that, when altered by the passage of a gear tooth,
generates an AC voltage in the coil. The AC voltage is proportional to speed. The frequency
of the AC signal is exactly proportional to speed (rpm).
Magnetic pickup sensors rely on the distance between the end of the pickup and the passing
gear teeth to operate properly. Typically when the pickup is installed, it is turned in until the
sensor makes contact with the top of a gear tooth and then turned back out a partial turn before
it is locked in place with a locking nut. A weak signal may indicate the sensor is too far away
from the gear. It is important to check the specifications when installing these sensors to insure
the proper spacing.
Transmission speed sensors may be used in pairs. The sensors are often called upper and
lower, top and bottom, or primary and secondary referring to the operating range they are
designed for. Although the sensors have an optimum operating range, in case of a failure the
ECM will use the signal from the remaining sensor as a backup. The speed sensor may be
checked for both static and dynamic operation. With the sensor disconnected from the machine
electrical harness, a resistance reading of the pickup coil (measured between pins) should read
a coil resistance of approximately 1075 ohms. Some magnetic pickups may measure as high as
1200 ohms. The resistance value differs between pickup types, but an infinite resistance
measurement would indicate an open coil, while a zero reading would indicate a shorted coil.
10/06

Transmission Oil Temperature Sensor
The transmission oil temperature sensor (1) is a two-wire passive temperature sensor that is
located on the right side of the machine. The sensor is an input to the Power Train ECM. The
oil temperature sensor information is used to adjust transmission clutch fill times.
The transmission oil temperature sensor information is also sent by the Power Train ECM to the
Caterpillar Monitoring System over the Cat Data Link.
Also shown are the torque converter oil temperature sensor (2) and the implement pump (3).
43
10/06
1
2
3

Left Brake Pedal Position Sensor
The left brake pedal position sensor (arrow) is located in the cab as part of the left brake pedal.
The position sensor (left brake pedal) sends an input to the Power Train ECM. The sensor
continuously generates a 500 Hz PM signal. The duty cycle varies in proportion to the position
of the left brake pedal position sensor. The left pedal position sends a change in the input
signal to the Power Train ECM. The ECM measures the duty cycle in order to determine the
position of the pedal for downshifting the transmission and neutralizing the clutches.
44
10/06

Implement Pod Downshift Switch And Remote FNR Switch
The downshift switch (1) is located on the implement pod. If the machine is equipped with a
joystick, the downshift switch will be located on the joystick handle.
When the Power Train ECM is operating in the Manual Mode, depressing the downshift switch
will cause a downshift from SECOND speed to FIRST speed. In the Manual Mode, the
downshift switch will not shift from FOURTH to THIRD speed or from THIRD to SECOND
speed. The transmission will remain in FIRST speed until one of the following conditions
occurs:
1. A directional shift is made.
2. The shift lever is moved to NEUTRAL before selecting a speed.
3. The shift lever is turned to FIRST speed and then to another speed.
When operating in the Automatic mode, depressing the downshift switch causes the
transmission ECM to downshift the transmission at a higher than normal ground speed.
Pressing and immediately releasing the downshift switch causes the transmission ECM to
immediately downshift the transmission one speed range. A downshift will occur only if the
machine speed and engine speed will not result in an engine overspeed.
Automatic shifting is disabled for five seconds after the downshift switch is pressed. After five
seconds, automatic shifting, based on speed sensor inputs, is reactivated.
NOTE: The remote FNR switch (2) is only installed on the machines that are equipped
with the standard HMU steering.
45
10/06
1 2

Parking Brake Pressure Switch
The parking brake pressure switch (1) is a normally closed switch with the parking brake
engaged. When the parking brake is engaged, the parking brake indicator light (3) will be
illuminated. When the parking brake knob is pushed to the IN position, the parking brake
valve (2) will direct oil pressure to the parking brake release cylinder. The switch state will
change, the parking brake indicator light will not be illuminated, and the Power Train ECM will
receive a signal that the parking brake is dis-engaged.
The parking brake pressure switch is located on the right side of the machine above the service
bay. The cover is transparent to show the location of the parking brake pressure switch.
46
47
10/06
1
2
3

48
Based on the input signals, the Power Train ECM energizes the appropriate transmission control
modulating valve for speed and directional clutch engagement. The Power Train ECM also
energizes the starter relay when starting the machine and the back-up alarm when the operator
selects a reverse gear.
The Cat Data Link connects the Power Train ECM to the other machine ECMs. The data link
also connects the ECM to the Caterpillar Monitoring System and electronic service tools such
as Caterpillar Electronic Technician (ETC).
Power Train ECM Outputs:
Engine start relay: The Power Train ECM energizes the key start relay when the appropriate
conditions are met to start the engine. Controls the current between the key start switch and the
starter relay.
Transmission oil filter bypass indicator LED: The Power Train ECM illuminates the
indicator LED when the oil is bypassing the transmission filter.
Low fuel level warning indicator LED: The Power Train ECM illuminates the indicator LED
when the fuel level in the tank is below 10% of total fuel tank volume as read by the fuel level
sensor (input to EMS-III communicated over Cat Datalink).
10/06
Clutch 3
4th Speed Solenoid
Clutch 4
3rd Speed Solenoid
Clutch 5
2nd Speed Solenoid
Clutch 2
Forward Solenoid
Clutch 1
Reverse Solenoid
Caterpillar Monitor
System
Power Train ECM
Cat Data Link
OUTPUT COMPONENTS
Clutch 6
1st Speed Solenoid
Engine Start Relay
Transmission Oil Filter
Bypass Indicator Led
Low Fuel Level
Warning Indicator LED
Transmission Neutralizer
Disabled Indicator LED
Ride Control ON
Indicator LED
Ride Control
Solenoid (Balance)
Ride Control
Antidrift Solenoid (RE)
Heated Mirror Relay
+24 Voltage
Ride Control
Antidrift Solenoid (HE)
Secondary Steering
Intermediate Relay
Back-up Alarm
POWER TRAIN ELECTRICAL SYSTEM
Axle Cooler Relay (option)

Ride Control ON indicator LED: The Power Train ECM illuminates the indicator LED when
ride control is active. Either in AUTO mode when driving above the threshold speed or when
in ON mode.
Clutch solenoids: The solenoids control the oil flow through the respective speed and
directional modulating valves.
Secondary steering intermediate relay: The Power Train ECM energizes the relay when the
loss of steering pressure is detected by the Power Train ECM. The ECM energizes the relay
and power is supplied to the secondary steering pump.
Back-up alarm: The Power Train ECM energizes the back-up alarm when the operator selects
the REVERSE direction. The backup alarm is located on the rear bumper.
Heated mirror relay: The Power Train ECM energizes the relay to send current to the coil to
warm the mirror.
CAN-J1939 signal between machine ECMs: Signals sent between the Machine ECMs and
product Link on the faster CAN Data Link.
Ride Control Solenoid valve 1 (RE): The Power Train ECM energizes the solenoid valve that
controls the opening of the antidrift valve allowing flow between the rod end of the lift
cylinders and tank.
Ride Control Solenoid valve 3 (HE): The Power Train ECM energizes the solenoid valve that
controls the opening of the antidrift valve allowing flow between the accumulator and the head
end of the lift cylinders.
Ride Control Solenoid valve 2 (Balance): At engine start-up, the Power Train ECM energizes
the solenoid valve 2. When the Power Train ECM recognizes the ground speed in AUTO
reaches the default threshold speed value in the Power Train ECM, the ECM de-energizes the
solenoid 2 for a default time designated through Caterpillar ETC configuration. The pressure
between the head end of the lift cylinders and the accumulator is balanced. Then the Power
Train ECM energizes the solenoid 1 and 3 ride control solenoids.
+8 Volts: Regulated power supply providing 8 VDC that is used in order to power the digital
sensors.
Axle Oil Cooler Relay (option): Energized by the Power Train ECM when the axle oil
temperature reaches 65° C (149° F). When the relay is energized, current is sent to the
electromagnetic clutch on the axle oil cooler pump.
10/06

Back-up Alarm
The backup alarm (arrow) is located on the right hand side of the machine inside the access
door. The alarm sounds when the transmission directional lever (HMU) or the transmission
directional switch (CCS) is placed in the REVERSE position.
49
50
10/06

Warning Panel - Left Side
The illustration shows the warning panel on the left side of the dash panel. These indicators are
driven outputs of the Power Train ECM.
The transmission oil filter bypass (1) is located on the top right hand side. This alarm is
illuminated when the transmission oil filter is bypassing due to a plugged filter requiring a
change.
The transmission neutralizer disabled indicator (2) is located in the center of the panel. This
indicator is illuminated when the transmission neutralized is disabled.
The low fuel filter warning indicator (3) is located in the center row on the right side. This
indicator is illuminated when the fuel level is below 10% of the total fuel tank volume.
The ride control SERVICE indicator (4) is located in the bottom row on left side. This
indicator is illuminated when the ride control switch is placed in the SERVICE position.
The ride control AUTO indicator (5) is located in the bottom row, center. This indicator is
illuminated when the ride control switch is placed in the AUTO position.
51
10/06
1
2 3
4 5

52
Implement Control Valve - With Ride Control
The ride control system is an option on the 950H and the 962H Wheel Loaders. The optional
ride control system provides a means for dampening the bucket forces which produce a pitching
motion as the machine travels over rough terrain. The operation of ride control is initiated by
the switch input to the Power Train ECM with outputs to the solenoid valves on the implement
control valve (1).
On the implement control valve, there are two solenoid valves that control oil flow over the
antidrift valves and one solenoid valve controlling the shifting of the balance valve. The
energizing solenoid valve (2) provides a path of oil between the head end of the lift cylinders
and the ride control accumulator. The energizing solenoid valve (3) allows the balance spool to
shift as the solenoid valve provides a path for the oil on the end of the balance spool to flow to
the hydraulic tank passage. The energizing solenoid valve (4) drains the oil pressure off the
antidrift valve enabling the valve to raise and allow oil to flow between the rod end of the lift
cylinders and the hydraulic tank.
The optional ride control is enabled through the Machine Configuration screen with Caterpillar
Electronic Technician (ET). When ride control system is in SERVICE/AUTO, the respective
LED is illuminated on the machine status display.
10/06
1
2
4
3

Secondary Steering Intermediate Relay
The secondary steering intermediate relay (1) is an output of the Power Train ECM. When the
steering oil pressure at the primary pressure switch goes below the value of the switch, a signal
is sent to the Power Train ECM (not shown) and the ECM sends current to intermediate relay to
energize the secondary steering pump motor.
53
10/06
1

Engine Start Relay
The engine start relay (2) is located in the left side service center (1). The engine start relay is
energized by the Power Train ECM when all the engine starting requirements are met. When
the engine start relay is energized, battery voltage flows through the relay to the starter
solenoid.
Also shown are the ground level shutdown switch (3) and the battery enclosure (transparent for
viewing) (4).
54
55
10/06
1
2
3
4

56
Transmission Hydraulic System - NEUTRAL
This illustration shows the transmission hydraulic system with the engine running and the
transmission shift lever in the NEUTRAL position.
When the engine is running, flow from the pump is sent through the filter to the six
transmission solenoid valves. Pump flow is also sent to the transmission relief valve. The
transmission relief valve limits the transmission oil pressure to the modulating valves. When
NEUTRAL is selected, the Power Train ECM energizes the No.3 solenoid. The modulating
valve controls the flow of oil to the No. 3 clutch.
When the No. 3 solenoid is energized, the oil flows through the center of the valve. Oil flow is
directed to the port for clutch 3.
From the main relief valve, oil flows to the torque converter and the torque converter inlet relief
valve. The torque converter inlet relief valve limits the oil pressure to the torque converter.
When oil pressure to the torque converter exceeds 900 ± 70 kPa (130 ± 10 psi), the inlet relief
valve opens and sends the excess oil pressure to drain.
10/06
Torque
Converter
Inlet Relief
Valve
Filter
Transmission
Pump
Tank
Main Relief Valve
Torque
Converter
Power Train
ECM
4
5
6
2
1
Torque Converter
Outlet Relief Valve
To
Transmission
Bearing
Lubrication
3
2
3
Modulating
Valve
Modulating
Valve
Modulating
Valve
Modulating
Valve
Screen Group
Magnet
TRANSMISSION HYDRAULIC SYSTEM
NEUTRAL
FORWARD
FOURTH
SPEED
SECOND
SPEED
4
Modulating
Valve
THIRD
SPEED
5
6
FIRST
SPEED
Modulating
Valve
1
REVERSE
Cooler

Oil in the torque converter flows out of the torque converter through the torque converter outlet
relief valve. The outlet relief valve maintains the pressure in the torque converter at a
minimum of 415 ± 135 kPa (60 ± 20 psi) at torque converter stall rpm.
From the torque converter outlet relief valve, the oil flows through the transmission oil cooler
and on to the transmission for cooling and lubrication of the bearings and planetaries.
10/06

57
transmission shift lever in the FORWARD position and the speed selector in FIRST SPEED.
transmission relief valve limits the transmission oil pressure to the modulating valves.
When FIRST SPEED FORWARD is selected, the Power Train ECM energizes the No. 2
solenoid and the No. 6 solenoid. The modulating valve controls the flow of oil to the No. 2 and
No. 6 clutches.
When the No. 2 and No. 6 solenoids are energized, oil flows through the center of the valve.
Oil flow is directed to the ports for clutch 2 and clutch 6.
10/06
Power Train
ECM
6
Torque
Converter
Inlet Relief
Valve
Filter
Transmission
Pump
Tank
Main Relief Valve
Torque
Converter
4
5
3
3
Modulating
Valve
1
Torque Converter
Outlet Relief Valve
To
Transmission
Bearing
Lubrication
Modulating
Valve
1 4
Modulating
Valve
Screen Group
Magnet
FIRST SPEED FORWARD
2
2
Modulating
Valve
FORWARD
REVERSE THIRD
SPEED
FOURTH
SPEED
Modulating
Valve
FIRST
SPEED
5
Modulating
Valve
SECOND
SPEED
6
Cooler

and on to the transmission for cooling and lubrication of the bearings and planetaries.
10/06

58
transmission shift lever in the FORWARD position and the speed selector in SECOND SPEED.
No. 5 clutches.
When the No. 2 and No. 5 solenoids are energized, the oil flows through the center of the
valves. Oil flow is directed to the ports for clutch 2 and clutch 5.
10/06
Power Train
ECM
6
Modulating
Valve
FIRST
SPEED
Torque
Converter
Inlet Relief
Valve
Filter
Transmission
Pump
Tank
Main Relief Valve
Torque
Converter
4
5
5
Modulating
Valve
SECOND
SPEED
3
3
Modulating
Valve
1
Torque Converter
Outlet Relief Valve
To
Transmission
Bearing
Lubrication
Modulating
Valve
1
Screen Group
Magnet
SECOND SPEED FORWARD
2
2
Modulating
Valve
FORWARD
REVERSE
FOURTH
SPEED
6
6
4
Modulating
Valve
THIRD
SPEED
Cooler

and on to the transmission for cooling and lubrication of the bearings and plan.
10/06

59
transmission shift lever in the REVERSE position and the speed selector in SECOND SPEED.
No. 5 clutches.
When the No. 1 and No. 5 solenoids are energized, the oil flow through the center of the valves.
Oil flow is directed to the ports for clutch 1 and clutch 5.
10/06
Power Train
ECM
6
Modulating
Valve
FIRST
SPEED
Torque
Converter
Inlet Relief
Valve
Filter
Transmission
Pump
Tank
Main Relief Valve
Torque
Converter
4
5
5
Modulating
Valve
SECOND
SPEED
3
3
Modulating
Valve
1
Torque Converter
Outlet Relief Valve
To
Transmission
Bearing
Lubrication
Modulating
Valve
2
REVERSE
Screen Group
Magnet
SECOND SPEED REVERSE
1
Modulating
Valve
FORWARD
2
FOURTH
SPEED
6
6
4
Modulating
Valve
THIRD
SPEED
Cooler

and on to the transmission for cooling and lubrication of the bearings and plan.
10/06

60
Transmission Modulating Valve - NO COMMANDED SIGNAL
In this illustration, the transmission modulating valve is shown with no current signal applied to
the solenoid. The transmission ECM controls the rate of oil flow through the transmission
modulating valves to the clutches by changing the signal current strength to the solenoids. With
no current signal applied to the solenoid, the transmission modulating valve is
DE-ENERGIZED and oil flow to the clutch is blocked. The transmission modulating valve is
located on the transmission control valve.
Pump oil flows into the valve body around the valve spool and into a drilled passage in the
center of the valve spool. The oil flows through the drilled passage and orifice to the left side
of the valve spool to a drain orifice. Since there is no force acting on the pin assembly to hold
the ball against the drain orifice, the oil flows through the spool and the drain orifice past the
ball to the tank.
The spring located on the right side of the spool in this view holds the valve spool to the left.
The valve spool opens the passage between the clutch passage and the tank passage and blocks
the passage between the clutch passage and the pump supply port. Oil flow to the clutch is
blocked. Oil from the clutch drains to the tank preventing clutch engagement.
10/06
From
Pump
Test Port
Ball
Valve
Spool Spring
Drain
Orifice
Solenoid Pin
To
Tank
To
Clutch
Orifice
TRANSMISSION MODULATING VALVE
NO COMMANDED SIGNAL

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