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 Occupant Restraint Controller (ORC).
The ORC microprocessor continuously monitors all of the passive restraint system electrical circuits to determine the
system readiness. If the ORC 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 ORC. The impact sensors and the ORC commu-
nicate by modulating the voltage in the sensor plus circuit.
The hard wired circuits between the front impact sensors and the ORC 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 ORC, 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 ORC, and the electronic
message communication between the sensors and the ORC 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 Occupant Restraint Controller (ORC).
The ORC microprocessor continuously monitors all of the side passive restraint system electrical circuits to deter-
mine the system readiness. If the ORC 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 the same left or right sensor plus and minus circuits in a series arrangement from the ORC. The impact
sensors and the ORC communicate by modulating the voltage in the sensor plus circuit.
The hard wired circuits between the side impact sensors, and those between the sensors and the ORC may be
diagnosed and tested using conventional diagnostic tools and procedures. However, conventional diagnostic meth-
ods will not prove conclusive in the diagnosis of the ORC, the impact sensors, or the electronic message inputs to
or outputs from the impact sensors. The most reliable, efficient, and accurate means to diagnose the impact sen-
sors, the ORC, and the electronic message communication between the sensors and the ORC 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.
HB
RESTRAINTS - SERVICE INFORMATION
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