1. GM SIR
Dual Air Bag
System
Instructor Guide
GM SIR Dual Air Bag System
Activity 1
Program Overview
Performance Objectives:
During this activity you will be introduced to the ATech GM SIR Dual Air Bag System.
After completing this activity, you will be able to:
• Locate and identify all of the tools and materials used in this program
• Understand the course objectives (what you should know afterwards)
• Understand how the trainer operates
• Locate technical information in the service manual and other resources efficiently
Tools and Materials:
• ATech Model 1551 ATech GM SIR Dual Air Bag System Trainer
References:
• Reference Book
• Service Manual Information
Locate the Following:
• ATech Model 1551 GM SIR Dual Air Bag System Trainer
• Student Manual
• Reference Book
• Service Manual Information
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2. Note that during this program, you will be asked to work with one or more of the above
mentioned “pieces of equipment”.
This Supplemental Inflatable Restraint (SIR) program is divided into separate activities. Each
activity contains questions from either the Reference Book or from the Service Manual
Information. Many of the activities also contain an On-Trainer portion which requires the use of
the ATech GM SIR Dual Air Bag System Trainer.
Reference Book:
The GM Supplement Restraint System (Air Bags) Reference Book contains information
covering the following topics:
• Introduction
• DERM Systems
• SDM Systems
• Side Impact Air Bag Systems
• Diagnosis, Tools, and Wire Repair
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3. Course Objectives:
• Read the Course Objectives on page IV in the Reference Book to answer the following question.
1. The objectives of the training program are listed below. Fill in the blanks with the
missing word or phrase:
a. Identify restraint systems from the Vehicle Identification Number (VIN)
b. Locate restraint system components on vehicle
c. Describe the operation of Inflator Modules
d. Describe the operation of Pretensioners
e. Describe the operation of DERM and Sensors
f. Describe the operation of the SDM and Sensors
g. Use special tools and the Tech 2 to test components and systems
h. Perform component and systems tests
i. Diagnose Trouble codes
j. Use Diagnostic Strategies
k. Retrieve Service Manual and Bulletin Information (paper manual and ESI)
Dual Air Bag Introduction:
• Read pages 1-1 through 1-18 in the Reference Book to answer the following questions.
2. What are the basic components that trigger the rapid inflation of the bag during an
impact of sufficient force?
a. System Control Module
b. Two or more sensors
c. Inflator Module
3. What character position of the VIN for a driver air bag system is the specific
character?
The seventh character position
4. In what four stages does the air bag system operate?
a. Before Deployment
b. Fully Deployed
c. During Restraint
d. End of Crash
5. How severe does the impact have to be before the air bag will deploy?
Equivalent to hitting a stationary vehicle at twenty-eight miles per hour.
6. “Ride down” is a term used in the Vehicle Safety Design. What does this term mean?
Stopping gradually over a greater distance
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4. 7. List the five main parts of the Driver Inflator Module.
a. Base Plate
b. Cushion (Air Bag)
c. Cushion Cover
d. Trim Cover
e. Inflator
8. List the five precautions for handling an inflator module that is not deployed.
a. Carry with trim side facing away
b. Never carry by the wires
c. Store with trim side facing up
d. Never store near loose, or flammable objects
e. Never store near a heat source capable of producing 65°C (149°F) or greater
temperatures.
9. A special procedure must be followed to ship an inflator module that is not deployed
(refer to the manufacturers Service Manual for the specific procedures).
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5. History of the Air Bag:
The initial Air Bags were called Air Cushions and were actually intended to replace seat
belts, rather than supplement them. Some of the first GM vehicles equipped with air cushion
devices had the seat belts removed for this reason. The air cushion as such appears to have been
invented as early as 1951. A key component, the actual Crash Sensor, was invented in the mid to
late 1960’s. However, it was not until the early 1970’s that a significant number of vehicles
were equipped with these air cushions. Some of the early 1970’s GM vehicles did have Dual
Stage systems, much like present-day air bags. A dual stage system may deploy at different
speed, or with different force, depending on the severity of the impact.
The public did not buy air bag (or cushion) equipped vehicles in sufficient numbers for
manufacturers to sustain production and these initial offerings were discontinued.
The air bag systems experienced a comeback in the early 1980’s. This time the air bag
was intended as a Supplemental Restraint System (SRS). Note that these systems may also be
called Supplemental Inflatable Restraint (SIR). In 1984 the United States government mandated
that all passenger vehicles produced from the beginning of 1989 should have air bags or
Automatic Seat Belts. (The automatic seat belt technology was soon abandoned.) In 1998, dual
bags were mandated. These systems are also less powerful than the earlier or first generation air
bags. The second generation technology is not intended to fully restrain vehicle occupants not
wearing a seat belt. Therefores, they are less likely to cause injury to passengers, especially
children.
The air bag technology has evolved from a purely mechanical system, housed in the
steering wheel, to an intelligent system using multiple bags, located in various locations on the
vehicle. These bags may be found in the knee bolster, as side curtains, and as roof bags as well
as a number of other locations. Often, automatic seat belt pre tensioners are used as a
complement. There may be occupant detection sensors which detect both the presence as well as
the weight of a passenger. The premise is simple, there is no point in activating (an expensive)
air bag if there is no one sitting in the seat. The deployment speed can be tailored to the weight
of the occupant as well. If a child is sitting in the seat, for example, the bag may deploy with less
force than if a full grown person is occupying the seat. This minimizes the chance of the actual
deployment harming the passenger. These types of air bag systems are known as Smart Air
Bags.
Using the information given above, please answer the following questions:
10.
The initial air bag systems were designed to replace rather than supplement seat belts.
11.
Why did Air Bags disappear from vehicles in the early to mid 1970’s?
They where sold in insufficient numbers for the manufacturers to continue
production.
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6. 12.
What is/are the main difference(s) between the first and the second generation Air Bags?
The second generation Air Bag is less powerful and therefore less likely to cause
harm to the occupant.
Service Manual Information:
• Refer to the Table of Contents in the Service Manual Information to answer the following
question.
11. What volume will Restraints be listed in? Volume Two
12. List the page numbers for:
Restraints
9-1
Seat belts
9-3
SIR
9-22
13. What section and page number is Seat Belt Description and Operation found?
Restraints – Seat Belts, page 9-21
14. What is the primary means of occupant restraint? Seat Belts
15. What section and page number is Supplemental Inflatable Restraint (SIR)
Description and Operation found?
SIR, page 9-80
Note: Active Restraints refers to seat belt systems, which require the occupant to take an “active”
part in buckling up. Passive Restraints refers to both automatic motorized seat belts and air
bags because the occupant doesn’t have to do anything (can remain “passive”) for the
restraint system to operate.
16. What two types of Restraint systems are there?
a. Active
b. Passive
Note: It is important to remember that seat belts should be worn in vehicles equipped with air
bags because the air bag is only deployed in moderate to severe frontal crashes, and is
intended to supplement the seat belts. The air bag does not protect the occupant in
rollovers, rear, or side collisions, or in less severe frontal impacts.
The contents of Section 9 in the Service Manual Information will be covered in greater detail in
Activity 2.
Complete the On-Trainer Worksheet at this time.
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7. ON-TRAINER WORKSHEET
Activity 1
Introduction
• Refer
to the ATech GM SIR Dual Air Bag System Trainer to answer the following questions.
The ATech GM SIR Dual Air Bag System Trainer displays an actual Chevrolet Cavalier/Sunfire
dual air bag system.
Inputs:
1. Identify the inflator sensors and connectors in the system.
a. Front End Discriminating Sensor
b. Arming Sensor
c. Sensing and Diagnostic Module (SDM)
d. Driver’s Side Air Bag Connector
e. Seat-Belt Connector
f. Passenger’s Air Bag Connector
g. Diagnostic Connector
2. What text color is used to identify these sensors? Blue
Note that ATech uses blue to indicate inputs to the system.
• Locate
the push button switches next to each sensor.
Figure 1. The switch used to simulate an impact. © ATech 1/11/2008
These switches are used to simulate sensors detecting a crash.
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8. Control:
• Locate the Sensing and Diagnostic Module (SDM).
The Sensing and Diagnostic Module maintains a 23-volt loop reserve for deployment of the air
bag in the event that Ignition 1 voltage is lost during a collision. It is important to note, when
disabling the SIR system for servicing or rescue operations one should allow the 23-volts to
dissipate which could take one minute.
Outputs:
• Locate the Air Bag Module in the center of the Steering Wheel.
• Locate
the Passenger Side Air Bag.
The Air Bag Modules are a disarmed cut away for training purposes and does not contain any
gas-generating material.
•
Locate the Air Bag Deployment Indicator (flash) behind the Steering Wheel.
•
Locate the Air Bag Deployment Indicator (flash) above the front passenger side air bag.
The indicators are used to simulate air bag deployment.
•
Locate the Air Bag Deployment Indicator light to the right of the SDM unit.
This indicator light is used to display trouble codes in the system.
3. What color is used to identify outputs? Red
Note that ATech uses red to indicate system outputs.
Conclusion:
The ATech GM SIR Dual Air Bag System Trainer can be used to observe the operation of an
actual air bag system without the hazards of working with a live air bag module. Both the frontend discriminating sensor and the arming sensor operation can be simulated. Actual diagnostic
and service procedures can be practiced, as they would be performed on a live vehicle.
The ATech GM SIR Dual Air Bag System Trainer will be used for “hands-on” practice
throughout this program.
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