Air Bag Control Module

Air bag Control Module (ACM), located in front of center console contains a microprocessor, an impact sensor and an energy storage capacitor. The microprocessor contains air bag system logic. Air bag system logic includes On-Board Diagnostics (OBD) capability.

ACM microprocessor monitors internal impact sensor signal and air bag system electrical circuits to determine system readiness. If ACM detects a monitored system fault, a message is sent through the PCI bus circuit to Electro-Mechanical Instrument Panel (EMIC) to turn air bag indicator light on. ACM is preprogrammed to determine when deceleration rate signaled by impact sensor indicates an impact severe enough to require air bag system protection. When preprogrammed conditions are met, ACM sends a signal to deploy air bag system components.

The impact sensor is an accelerometer that senses the rate of vehicle deceleration, which provides verification of direction and severity of an impact. Impact sensor is calibrated for specific vehicle, and is only serviced as an integral part of ACM.

EMIC module performs air bag indicator light check when ignition switch is turned to RUN or START position. EMIC module turns indicator light on for 6-8 seconds. Light turns off if ACM determines no system malfunctions exist. Light remains on if ACM determines an air bag system malfunction or if EMIC light circuit short to ground exists. For additional information on air bag system, see appropriate AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS.