Air Bag Control Module: Description and Operation

AIR BAG CONTROL MODULE (ACM)
The ACM/Air Bag System Diagnostic Module (ASDM) contains safing sensor and energy reserve capacitor, while the ACM/Air Bag Electronic Control Module (AECM) contains impact sensor and energy reserve capacitor. The ACM monitors system to determine system readiness. The ACM will store sufficient energy to deploy air bag for two minutes after battery has been disconnected. The ACM contains an on board diagnostics function that will illuminate air bag warning lamp when a system fault occurs.

CIRCUIT DESCRIPTION AND OPERATION

Three different circuits and fuses supply battery voltage to the Airbag Control Module (ACM), they are A14, F20 and G5. The A14 circuit is HOT at all times and protected by two fuses located in cavities 3 and 15 of the Power Distribution Center (PDC).

The F20 and G5 circuits are connected to separate bus bars internal to the fuse block. Different circuits from the PDC and the ignition switch supply battery voltage to the fuse block bus bars.

The F20 circuit supplies battery voltage to the ACM only when the ignition switch is in the RUN position. The G5 circuit powers the ACM when the ignition switch is in either the START or RUN position.

A bus bar internal to the ignition switch connects the A1 circuit from the Power Distribution Center (PDC) to the A21 circuit when the switch is in either the START or RUN position. The A21 circuit supplies battery voltage to the fuse block bus bar that feeds the G5 circuit. A 40 amp fuse in the PDC protects the A1 and A21 circuits. A 15 amp fuse in cavity 22 of the fuse block protects the G5 circuit.

When the ignition switch is in the RUN position, it connects the A2 circuit from the PDC to the A22 circuit. The A22 circuit supplies battery voltage to the fuse block bus bar that feeds the F20 circuit. A 60 amp fuse in cavity 13 of the PDC protects the A2 and A22 circuits. A 15 amp fuse in cavity 18 of the fuse block protects the F20 circuit.

The ACM has an external dedicated ground, circuit Z6.