RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Body Control Module: Description and Operation
Airbag System
AIRBAG SYSTEM
The airbag system is designed to provide increased driver and passenger protection if the vehicle is involved in a front end collision. The system is most
effective when used in conjuction with the seat belt system.
The Airbag Control Module (ACM) is an electronic module that monitors the airbag system for proper operation, stores diagnostic trouble code
(DTC's), controls the airbag warning lamp and contains the sensor and actuator that is responsible for airbag deployment. There are no external impact
sensors. The ACM is mounted on a special bracket that is fastened to the floor of the truck at the bottom of the instrument panel. It is located forward of
the console. The ACM provides diagnostic information (DTC's) to the technician through the DRB III via the PCI bus. Some circuits are tested
continously; others are checked only under certain circumstances. The warning lamp is driven with messages relayed to the Electro/Mechanical
Instrument Cluster (EMIC) from the ACM via the PCI bus.
The AIRBAG warning lamp is the only point at which "symptoms" of a system malfunction can be observed by the customer. Whenever the ignition key
is turned to the "run" position, the airbag control module performs a lamp check by turning the AIRBAG warning lamp ON for 6-8 seconds. If the lamp
remains OFF, it means that the ACM has checked the system and found it to be free of discernible malfunctions. If the lamp remains ON, there could be
an active fault in the system or the circuit that operates the lamp may be shorted to ground. If the lamp comes ON and stays ON for a period longer than
6-8 seconds, then goes OFF, there is usually an intermittent problem in the system.
WARNING: 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.
Driver Airbag
The airbag protective trim cover is the most visible part of the driver side airbag system. The protective trim cover is fitted to the front of the airbag
module and forms a decorative cover in the center of the steering wheel. The module is mounted directly to the steering wheel. Located under the trim
cover are the horn switch, the airbag cushion, and the airbag cushion supporting components. The airbag module includes a housing to which the cushion
and hybrid inflator are attached and sealed. The airbag module cannot be repaired, and must be replaced if deployed or in any way damaged.
Clockspring
The clockspring is mounted on the steering column behind the steering wheel. This assembly consist of a plastic housing which contains a flat,
ribbon-like, electrically conductive tape that winds and unwinds with the steering wheel rotation. The clockspring is used to maintain a continuous
electrical circuit between the instrument panel wiring and the driver airbag, the horn, and the vehicle speed control switches if equipped. The clockspring
must be properly centered when it is reinstalled on the steering column following any service procedure, or it could be damaged. The clockspring cannot
be repaired and it must be replaced.
Passenger Airbag
When supplied with the proper electrical signal the passenger airbag inflator or inflators discharge the gas directly into the cushion. The airbag module
cannot be repaired, and must be replaced if deployed or in any way damaged.
WARNING: THE PASSENGER AIRBAG MODULE CONTAINS ARGON GAS PRESSURIZED TO 17236.89 Kpa (2500 PSI). DO NOT
ATTEMPT TO DISMANTLE AN AIRBAG MODULE OR TAMPER WITH ITS INFLATOR. DO NOT PUNCTURE,
INCINERATE, OR BRING INTO CONTACT WITH ELECTRICITY. DO NOT STORE AT TEMPERATURE EXCEEDING 93
° C (200° F). REPLACE AIRBAG SYSTEM COMPONENTS ONLY WITH PARTS SPECIFIED IN THE MOPAR PARTS
CATALOG. SUBSTITUTE PARTS MAY APPEAR INTERCHANGEABLE, BUT INTERNAL DIFFERENCES MAY RESULT
IN INFERIOR OCCUPANT PROTECTION. THE FASTENERS, SCREWS, AND BOLTS ORIGINALLY USED FOR THE
AIRBAG SYSTEM COMPONENTS HAVE SPECIAL COATINGS AND ARE SPECIFICALLY DESIGNED FOR THE
AIRBAG SYSTEM. THEY MUST NEVER BE REPLACED WITH ANY SUBSTITUTES. ANY TIME A NEW FASTENER IS
NEEDED, REPLACE IT WITH THE CORRECT FASTENERS PROVIDED IN THE SERVICE PACKAGE OR SPECIFIED IN
THE MOPAR PARTS CATALOG.
Passenger Airbag ON-OFF Switch
