Toyota Camry and Avalon 1997-2000

General Information

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The air bag system used on the Camry and Avalon is referred to as Supplemental Restraint System (SRS). The SRS provides additional protection for the driver, if a forward collision of sufficient force is encountered. The SRS assists the normal seatbelt restraining system by deploying an air bag, via the steering column.



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Fig. Supplemental Restraint System (SRS) component locations

The center air bag sensor is the heart of the SRS. It consists of safing sensors, ignition control and drive circuit, diagnosis circuit, etc. The center air bag receives signals from the air bag sensors and determines whether the air bag must be activated or not. The center air bag sensor is also used to diagnose system malfunctions.

The air bag warning light circuit is equipped with an electrical connection check mechanism which detects when the connector to the center air bag sensor assembly is not properly connected.

All connectors in the air bag system are colored yellow. These connectors use gold-plated terminals with twin-lock mechanism. This design assures positive locking; there-by, preventing the terminals from coming apart.

SYSTEM OPERATION

When the ignition switch is turn to the ON or ACC position, the air bag warning lamp will turned ON for approximately 6 seconds. If no malfunctions are detected in the system, after the 6 second period have elapse, the warning light will go OFF .

The safing sensors are designed to go ON at a lower deceleration rate than the front or center air bag sensor. When the vehicle is involved in a frontal collision, the shock is great enough to overcome the predetermine level of the front or center air bag sensor. When a safing sensor and a front air bag sensor and/or the center air bag sensor go ON simultaneously, it causes the squib of the air bag to ignite and the air bag is deployed automatically. The inflated bag breaks open the steering wheel pad.

After air bag deployment have occurred, the gas is discharged through the discharge holes provided behind the bag. The bag become deflated as a result.

The connector of the air bag contains a short spring plate, which provides an activation prevention mechanism. When the connector is disconnected, the short spring plate automatically connects the power source and grounding terminals of the inflator module (squib).

SERVICE PRECAUTIONS
  1. Work must be started at least after 90 seconds from the time the ignition switch is turned to the LOCK position and the negative battery cable has been disconnected. The SRS is equipped with a back-up power source so that if work is started within 90 seconds of disconnecting the negative battery cable, the SRS may deploy. When the negative terminal cable is disconnected from the battery, memory of the clock and radio will be canceled. Before you start working, make a note of the contents memorized by the audio memory system. When you have finished working, reset the audio systems and adjust the clock. Never use a back-up power supply from outside the vehicle.
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  3. In the event that of a minor frontal collision where the air bag does not deploy, the steering wheel pad, front air bag sensors and center air bag sensor assembly should be inspected.
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  5. Before repairs, remove the air bag sensors if shocks are likely to be applied to the sensors during repairs.
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  7. Never disassemble and repair the steering wheel pad, front air bag sensors or center air bag sensors.
  8.  
  9. Do not expose the steering wheel pad, front air bag sensors or center air bag sensor assembly directly to flames or hot air.
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  11. If the steering wheel pad, front air bag sensors or center air bag sensor assembly have been dropped, or there are cracks, dents or other defects in the case, bracket or connectors, have them replaced with new ones.
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  13. Information labels are attached to the periphery of the SRS components. Follow the instructions of the notices.
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  15. After arming the system, check for proper operation of the SRS warning light.
  16.  
  17. If the wiring harness in the SRS system is damaged, have the entire harness assembly replaced.
  18.  

DISARMING THE SYSTEM

Work must be started only after 90 seconds from the time the ignition switch is turned to the LOCK position and the negative battery cable has been disconnected. The SRS is equipped with a back-up power source so that if work is started within 90 seconds of disconnecting the negative battery cable, the SRS may deploy. When the negative terminal cable is disconnected from the battery, memory of the clock and radio will be canceled. Before you start working, make a note of the contents memorized by the audio memory system. When you have finished work, reset the audio systems as before and adjust the clock. To avoid erasing the memory of each system, never use a back-up power supply from outside the vehicle.

ARMING THE SYSTEM

Reconnect the negative battery cable and perform the airbag warning light check by turning to the ON or ACC position, the air bag warning lamp will turned ON for approximately 6 seconds. If no malfunctions are detected in the system, after the 6 second period have elapse, the warning light will go OFF .

 
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