Chapter 65

[object Object],[object Object],[object Object],[object Object],[object Object],OBJECTIVES: After studying Chapter 65, the reader should be able to:

[object Object],[object Object],[object Object],[object Object],KEY TERMS:

HIGH-VOLTAGE SAFETY EQUIPMENT ,[object Object],Continued WARNING: HV cables and wiring are orange in color. High-voltage insulated safety gloves and a face shield must be worn when carrying out any diagnostics involving the high-voltage systems or components. The Occupational Safety and Health Administration ( OSHA ) requirements specify that HV gloves get inspected every six months by a qualified glove inspection laboratory. Use an outer leather glove to protect the HV rubber gloves. Inspect the gloves carefully before each use. High voltage and current (amperes) in combination is fatal. See Figures 65-1 & 65-2.

Figure 65–1 Rubber linesman’s gloves protect the wearer from a shock hazard. Figure 65–2 Wearing leather gloves over the linesman’s gloves helps protect the rubber gloves from damage. Continued NOTE: The high-voltage insulated safety gloves must be recertified every six months to remain within OSHA guidelines.

[object Object],Figure 65–3 Checking rubber linesman’s gloves for pinhole leaks. Continued ,[object Object],[object Object]

FIRST RESPONDER PROCEDURES ,[object Object],Figure 65–4 This Honda Accord hybrid is identified by the emblem on the rear deck lid. Figure 65–5 A hybrid electric vehicle can often be identified by looking for orange-colored cables under the hood, as well as other markings on the engine cover. Orange cables underhood or shielding bolted to the underside of the vehicle, indicates the vehicle is a hybrid.

[object Object],Continued Power Source The main power source of all hybrids is a conventional internal combustion engine (ICE). During start-up and acceleration, an electric motor provides assistance to the engine. During braking and deceleration, the motor acts as a generator, recharging both high-voltage and the 12-volt battery. 12-Volt Battery A conventional flooded-type lead-acid 12-volt battery, powers all standard electronics. Most are nonspillable absorbed glass mat (AGM) designs. This battery also provides power to the high-voltage battery control systems. Disconnecting or cutting the negative cables to the battery may be necessary in some emergency situations.

Figure 65–6 A Toyota Highlander hybrid battery pack with the cover removed. ,[object Object],Continued For safety, the high-voltage battery box is positioned behind seat backs or under the rear seat where it is well protected from potential damage in a collision. In the finished cells, electrolyte is nonliquid, nonflammable, nonexplosive, and creates no hazardous fumes or vapors in normal operating conditions and is sealed in a metal case. Small quantities of electrolyte, corrosive to human tissue, are used in NiMH battery cells.

[object Object],[object Object],[object Object],WARNING: Extreme heat (320–356°F [160–180°C]) can cause unintended airbag inflation. Follow recommended procedures to avoid possible injury from a deploying airbag or inflator. Airbags and Tensioners All hybrids have front airbags and seat belt tensioners. Most have side airbags for front-seat occupants; many with side curtain airbags. These systems use pyrotechnic devices with a deactivation time of up to three minutes.

ELECTRIC SHOCK POTENTIAL ,[object Object],Continued Receiving an electric shock from a hybrid vehicle is highly unlikely because of the following: ,[object Object],[object Object],[object Object],[object Object]

[object Object],Continued ,[object Object],[object Object],[object Object]

NOTE: The only condition common to all three situations in which the cables can be “hot” is that the ignition is on. Therefore, when the ignition switch is off, electric current cannot flow into the high-voltage cables because the system main relays that control the high voltage are turned off when the ignition is off. See the chart on Page 790 of your textbook.

[object Object],PREVENTING CURRENT FLOW THROUGH HIGH-VOLTAGE CABLES Continued Method One Turn the Ignition Switch Off This action turns off the engine and the electric motor, preventing current flow into the cables. It also turns off power to the airbags and the seat belt tensioners. Remove the key so the vehicle cannot be restarted. There are two recommended methods: NOTE: Turning the ignition key to the OFF position stops the flow of electricity in the cables.

[object Object],Figure 65–7 The high-voltage disconnect (service) plug is located on the left side of the rear seat in a Toyota Highlander hybrid vehicle. ,[object Object],This also cuts power to the airbags and the seat belt tensioners, as well as to the high-voltage battery controllers, preventing current from flowing into the cables from the high-voltage battery. Continued

[object Object],WARNING: Power remains in the high-voltage electrical system for up to 10 minutes after the HV battery pack is shut off. Never touch, cut, or open any orange high-voltage power cable or high-voltage component without confirming that the high voltage has been completely discharged. Continued

See the chart on Page 791 of your textbook. 3. Locate the 12-volt battery and cut the negative cables with diagonal cutters. See the 12-volt battery location chart below. NOTE: If neither method to stop the engine can be performed to prevent current flow into the high-voltage cables, use extreme care, do not cut into the cables, and do not touch damaged cables as they may be “hot.”

[object Object],Never assume the vehicle is shut off just because the engine is off. Always look for the READY indicator status. The vehicle is shut off when the READY indicator is off. The vehicle may be powered by: Silence is Not Golden 1 . The electric motor only 2 . The gasoline engine only 3 . A combination of both Figure 65–8 The Ford Escape Hybrid instrument panel showing the vehicle in Park and the tachometer on “EV” instead of 0 rpm. This means that the gasoline engine could start at any time depending on the state of charge of the high-voltage batteries and other factors.

[object Object],Continued WARNING: The SRS computer is equipped with a backup source that powers the SRS airbags up to 90 seconds after disabling the vehicle. The front-seat side airbags and the curtain-shield side airbags may deploy independent of each other.

Both positive and negative high-voltage power cables are isolated from the metal chassis, so there is no possibility of shock by touching the metal chassis. This design is called a floating ground. High Voltage is Insulated from the Vehicle Body A ground fault monitor continuously monitors for high-voltage leakage to the metal chassis while the vehicle is running. If a malfunction is detected, the vehicle computer will illuminate the master warning light in the instrument cluster and the hybrid warning light in the LCD display. The HV battery pack relays will automatically open to stop electricity flow in a collision sufficient to activate the SRS airbags.

EMERGENCY RESPONSE ,[object Object],Continued WARNING: Never assume a hybrid vehicle is shut off simply because it is silent. After disabling the vehicle, power is maintained for 90 seconds in the SRS system and 10 minutes in the high-voltage electrical system. Extrication 1. Immobilize the vehicle (chock wheels and set parking brake). 2. Disable the vehicle . 3. Stabilize the vehicle . Crib at four points directly under the front and rear pillars. Do not place cribbing under the high-voltage power cables, exhaust system, or fuel system.

Continued 4. Access the patients . Use normal glass removal procedures.Door removal/displacement. Doors can be removed by conventional rescue tools such as hand, electric, and hydraulic. 5. Door removal/displacement . Doors can be removed by conventional rescue tools such as hand, electric, and hydraulic. 6. Roof removal . The vehicle may contain optional curtain-shield airbags. If equipped and undeployed, it is not recommended to remove or displace the roof. CAUTION: Responders need to be cautious when working in close proximity to undeployed airbags and seat belt pretensioners. Deployed front dual-stage airbags automatically ignite both stages within a fraction of a second.

Continued 7. Dash displacement . The vehicle may contain optional curtain-shield airbags. When equipped, do not remove or displace the roof during a dash displacement to avoid cutting into the airbags or inflators. 8. Rescue lift airbags . Responders should not place cribbing or rescue lift airbags under the high-voltage power cables, exhaust system, or fuel system. 9. Fire . Approach and extinguish a fire using proper vehicle firefighting practices as recommended by NFPA, IFSTA, or the National Fire Academy (NFA). Water has been proven to be a suitable extinguishing agent. Perform a fast, aggressive fire attack. Attack teams may not be able to identify the vehicle as being a hybrid until the fire has been extinguished.

[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],Neutralize NiMH electrolyte using a boric acid solution or vinegar; boric acid solution is 5.5 ounces boric acid to 1 gallon of water (800 grams boric acid to 20 liters water).

VEHICLE FIRE ,[object Object],NOTE: If a fire occurs in the NiMH HV battery pack, the incident commander will have to decide whether to pursue an offensive or defensive attack. Continued

[object Object],Continued Defensive Fire Attack If the decision has been made to fight the fire using a defensive attack, the fire attack crew should pull back a safe distance and allow the NiMH battery modules to burn out. During this defensive operation, fire crews may utilize a water stream or fog pattern to protect exposures or to control smoke.

[object Object],SUBMERGED OR PARTIALLY-SUBMERGED VEHICLE NOTE: There is no risk of electric shock from touching the body or the framework whether in or out of the water. Submersion Handle a hybrid vehicle fully or partially submerged in water by disabling HV battery pack, SRS airbags, and fuel pump. ,[object Object],[object Object]

No. The computer of all hybrid electric vehicles monitors the connection between the high-voltage circuits and the body or frame of the vehicle. If water or an accident were to cause an electrical connection between high voltage and the body of the vehicle, high voltage is immediately turned off. Will I Get Shocked If I Drive My Hybrid Into Deep Water?

COLLISION AND REPAIR INDUSTRY ISSUES ,[object Object],Continued Using a jump box or jumper cable from another vehicle, make the connections to the positive and negative battery terminals. Figure 65–9 Jump-starting a 2001–2003 Toyota Prius using a 12-volt supply to boost the 12-volt auxiliary battery in the trunk.

[object Object],Figure 65–10 The underhood 12-volt jump-start terminal on this 2004+ Toyota Prius has a red plastic cover with a “+” sign. The positive booster cable clamp will attach directly to the vertical metal bracket. NOTE: The high-voltage HV battery pack cannot be jump started on most HEVs. One exception is the Ford Escape/Mercury Mariner hybrids, which use a special “jump-start” button located behind the left kick panel. When this button is pushed, the auxiliary battery is used to boost the HV battery through a DC-DC converter.

MOVING AND TOWING A HYBRID ,[object Object],Continued

Figure 65–11 Use of a warning cover over the steering wheel helps others realize that work is being performed on the high-voltage system and that no one is to attempt to start or move the vehicle. ,[object Object],Figure 65–12 A lock box is a safe location to keep the ignition keys of a hybrid electric vehicle while it is being serviced. Notice that this lock box has two separate locks so it would require two people to open, helping to insure that no harm is done by accidentally attempting to start a HEV. Continued

[object Object],Figure 65–13 Insulated tools, such as this socket set, would provide an additional margin of safety to the service technician when working around high-voltage components and systems. Continued Always check for voltage as the components become accessible before proceeding. When removing high-voltage components, it is wise to use insulated tools.

[object Object],Figure 65–14 The high-voltage wiring on this Honda hybrid is colored orange for easy identification. Continued

NiMH batteries do not store well for long lengths of time. After a repair job, or when the HV system has been powered down by a technician and powered up again, do not be surprised if a warning light(s), codes, and the MIL are illuminated. If everything was done correctly, a couple road tests may be all that is required to reset the MIL. The HV battery indicator on the dash may also read zero charge level. After a road test, the HV battery level indicator will most likely display the proper voltage level. High Voltage Battery SOC Considerations

INSULATION TESTER ,[object Object],Continued ,[object Object],[object Object],[object Object]

SUMMARY ,[object Object],[object Object],[object Object],Continued

SUMMARY ,[object Object],[object Object],[object Object],[object Object],( cont. )

Chapter 65

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Chapter 65