OPERATION
FRONT
The front impact sensors are electronic accelerometers that sense the rate of vehicle deceleration, which provides
verification of the direction and severity of an impact. Each sensor also contains an electronic communication chip
that allows the unit to communicate the sensor status as well as sensor fault information to the microprocessor in
the Airbag Control Module (ACM).
The ACM microprocessor continuously monitors all of the passive restraint system electrical circuits to determine the
system readiness. If the ACM detects a monitored system fault, it sets a Diagnostic Trouble Code (DTC) and con-
trols the airbag indicator operation accordingly. The impact sensors each receive battery current and ground through
dedicated left and right sensor plus and minus circuits from the ACM. The impact sensors and the ACM communi-
cate by modulating the voltage in the sensor plus circuit.
The hard wired circuits between the front impact sensors and the ACM may be diagnosed and tested using con-
ventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in
the diagnosis of the ACM, the impact sensors, or the electronic message inputs to or outputs from the impact sen-
sors. The most reliable, efficient, and accurate means to diagnose the impact sensors, the ACM, and the electronic
message communication between the sensors and the ACM requires the use of a diagnostic scan tool. Refer to the
appropriate diagnostic information.
SIDE
The side impact sensors are electronic accelerometers that sense the rate of vehicle deceleration, which provides
verification of the direction and severity of an impact. Each sensor also contains an electronic communication chip
that allows the unit to communicate the sensor status as well as sensor fault information to the microprocessor in
the Airbag Control Module (ACM).
The ACM microprocessor continuously monitors all of the side passive restraint system electrical circuits to deter-
mine the system readiness. If the ACM detects a monitored system fault, it sets a Diagnostic Trouble Code (DTC)
and controls the airbag indicator operation accordingly. The impact sensors each receive battery current and ground
through dedicated left and right sensor plus and minus circuits from the ACM. The impact sensors and the ACM
communicate by modulating the voltage in the sensor plus circuit.
The hard wired circuits between the side impact sensors and the ACM may be diagnosed and tested using con-
ventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in
the diagnosis of the ACM, the impact sensors, or the electronic message inputs to or outputs from the impact sen-
sors. The most reliable, efficient, and accurate means to diagnose the impact sensors, the ACM, and the electronic
message communication between the sensors and the ACM requires the use of a diagnostic scan tool. Refer to the
appropriate diagnostic information.
REMOVAL
FRONT
WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental
restraint system before attempting any steering wheel, steering column, airbag, occupant classification sys-
tem, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect
and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge
before performing further diagnosis or service. This is the only sure way to disable the supplemental
restraint system. Failure to take the proper precautions could result in accidental airbag deployment.
WARNING: To avoid personal injury or death, never strike or drop the front impact sensor, as it can damage
the impact sensor or affect its calibration. The front impact sensor enables the system to deploy the front
supplemental restraints. If an impact sensor is accidentally dropped during service, the sensor must be
scrapped and replaced with a new unit. Failure to observe this warning could result in accidental, incom-
plete, or improper front supplemental restraint deployment.
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RESTRAINTS - SERVICE INFORMATION
KJ