Air Bag Control Module: Description and Operation

DESCRIPTION
The Airbag Control Module (ACM) contains the impact sensor, and a microprocessor that monitors the impact sensor and the airbag system electrical circuits to determine the system readiness. The ACM contains On-Board Diagnostics (OBD), and will send an airbag lamp-on message to the instrument cluster on the Chrysler Collision Detection (CCD (Information)) data bus to light the airbag indicator lamp in the instrument cluster when a monitored airbag system fault occurs.

OPERATION
The ACM also contains an energy-storage capacitor. This capacitor stores enough electrical energy to deploy the airbags for up to one second following a battery disconnect or failure during an impact. The purpose of the capacitor is to provide airbag system protection in a severe secondary impact, if the initial impact has damaged or disconnected the battery, but was not severe enough to deploy the airbags.

The ACM cannot be repaired and, if damaged or faulty, it must be replaced.

CIRCUIT OPERATION
This vehicle has a drivers airbag and a passenger airbag. The Airbag Control Module (ACM) operates both.

In the START or RUN position, the ignition switch connects circuit A1 from fuse 3 in the Power Distribution Center (PDC) to circuit A21. Circuit A21 powers circuit F14 through fuse 9 in the fuse block. Circuit F14 connects to the ACM.

When the ignition switch is in the RUN position, it connects circuit A2 from PDC fuse 2 to circuit A22. Circuit A22 powers circuit F23 through fuse 5 in the fuse block. Circuit F23 connects to the ACM. The ACM has a dedicated ground on circuit Z6. The ACM is also case grounded.