RAM 2500 Van V8-318 5.2L VIN T Magnum CNG SFI (1997)
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) 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
Two circuits provide battery voltage to the Airbag Control Module (ACM); F14 and F23. Circuits F14 and F23 are connected to separate bus bars
in the fuse block. Different circuits from the Power Distribution Center (PDC) and the ignition switch supply battery voltage to the fuse block bus
bars.
Circuit F23 supplies battery voltage to the ACM only when the ignition switch is in the RUN position. Circuit F14 circuit powers the ACM when
the ignition switch is in either the START or RUN position.
In either the START or RUN position, the ignition switch connects circuit A1 from fuse 16 in the PDC with circuit A21. Circuit A21 circuit
supplies battery voltage to the fuse block bus bar that feeds circuit F14. Fuse 18 in the fuse block protects circuit F14. Circuit F14 connects to the
ACM.
When the ignition switch is in the RUN position, it connects circuit A2 from fuse 3 in the PDC to circuit A22. Circuit A22 supplies battery voltage
to the fuse block bus bar that feeds circuit F23. Fuse 1 in the fuse block protects circuit F23. Circuit F23 connects to the ACM.
The ACM has an external dedicated ground on circuit Z6.
