RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Air Bag Control Module: Description and Operation
Side Impact Airbag Control Module (SIACM)
WARNING: THE AIRBAG SYSTEM IS A SENSITIVE, COMPLEX ELECTROMECHANICAL UNIT.
THE AIRBAG CONTROL MODULE CONTAINS THE IMPACT SENSOR, WHICH ENABLES THE SYSTEM TO DEPLOY
THE AIRBAG.
BEFORE ATTEMPTING TO DIAGNOSE OR SERVICE ANY AIRBAG SYSTEM OR RELATED STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COMPONENTS YOU MUST FIRST DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE. THEN WAIT TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE FURTHER SYSTEM SERVICE.
THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO DO THIS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
NEVER STRIKE OR KICK THE AIRBAG CONTROL MODULE, AS IT CAN DAMAGE THE IMPACT SENSOR OR
AFFECT ITS CALIBRATION. IF AN AIRBAG CONTROL MODULE IS ACCIDENTALLY DROPPED DURING SERVICE,
THE MODULE MUST BE SCRAPPED AND REPLACED WITH A NEW UNIT
Fig. 53 Side Impact Airbag Control Module
SIDE IMPACT AIRBAG CONTROL MODULE
Supplemental driver and front passenger curtain airbags provide side impact protection for the front and rear seat occupants. Each curtain airbag has its
own side impact airbag control module (SIACM) to provide independent impact sensing and deployment. SIACM are located on the left and right B
post just below the seat belt retractor. The SIACM performs self diagnostics and circuit tests to determine if the system is functioning properly. If the test
finds a problem the SIACM will set both active and stored diagnostic trouble codes. The results of the system test are transmitted on the PCI Bus to the
ACM once each second. If the warning lamp status message from either SIACM contains a lamp ON request, the ACM will set an active DTC. At the
same time as the DTC is set the ACM sends a PCI Bus message to the mechanical instrument cluster (MIC) requesting the airbag warning lamp be
turned ON. Observe all ACM warning and caution statements when servicing or handling the SIACM. SIACM are not repairable and must be replaced if
they are dropped.
On vehicles equipped with the optional side curtain airbags, a Side Impact Airbag Control Module (SIACM) and its mounting bracket are secured with
four screws to the inside of each B-pillar behind (standard cab) or above (quad cab) the front outboard seat belt retractor, and concealed behind the
B-pillar trim. Concealed within a hollow in the center of the die cast aluminum SIACM housing is the electronic circuitry of the SIACM which includes
a microprocessor and an electronic impact sensor. The SIACM housing is secured to a die cast (standard cab) or stamped steel (quad cab) mounting
bracket, which is unique for the right or left side application of this component. The SIACM should never be removed from its mounting bracket. The
housing also receives a case ground through this mounting bracket when it is secured to the vehicle. A molded plastic electrical connector receptacle that
exits the top of the SIACM housing connects the unit to the vehicle electrical system through a dedicated take out and connector of the body wire
harness. Both the SIACM housing and its electrical connection are sealed to protect the internal electronic circuitry and components against moisture
intrusion.
The impact sensor internal to the SIACM is calibrated for the specific vehicle, and is only serviced as a unit with the SIACM. The SIACM cannot be
repaired or adjusted and, if damaged or faulty, it must be replaced.
