Airbag System: Notes

WARNING: This page is about a different car, the 2006 Dodge Sprinter. However, it is still accessible from the selected car via links, so may be relevant.

The Sprinter Airbag System contains the following components:

Airbag Control Module (ACM)
Airbag Warning Indicator (SRS)
Driver Airbags
Clockspring
Passenger Airbag
Driver Seat Belt Tensioners
Passenger Seat Belt Tensioners

The Airbag Control Module (ACM) has five major functions: onboard diagnostics, determine the severity of impacts, squib deployment and Accident Response, K-Line communications. The ACM is secured to the floor under the Driver seat and receives power from the Fuse Block No. 1. Whenever the ignition key is turned to the run or start position, the ACM performs a system test. The ACM cannot be repaired or adjusted.

The microprocessor in the ACM monitors the internal and external airbag system electrical circuits to determine the system readiness. When a monitored system is determine to be out of range, the ACM will set both active and stored diagnostic trouble codes (DTC). The ACM also contains an energy-storage capacitor. This capacitor stores enough electrical energy to deploy the front airbag components for two seconds following a battery disconnect or failure during an impact.

The Accelerometer in the ACM is used to sense the rate of vehicle deceleration, provide verification of the direction and severity of an impact. When the preprogrammed conditions are met, the ACM sends an electrical signal to deploy the appropriate front airbag system components and a deployment notification.

To provide an accident response notification, the ACM is hardwired to the Central Timer module (CTM) and Engine Control Module (ECM). When a deployment occurs the ACM provides a 50ms 10.0 volt pulse to the CTM and ECM. When the Accident Report notification signal is received the CTM unlocks the door locks and the ECM stalls the engine. The Accident signal will set a DTC in the CTM and the door locks will not work until the DTC has been erased. The ECM will set a DTC if the Accident Report circuit is shorted to battery voltage. The ACM saves the deployment record and after three deployments the ACM must be replaced. The DRBIII® can be used to test the Accident Report Notification feature: select the SYSTEM TEST from the ACM main menu. Then select the Analog Crash Output System Test.

The ACM is hardwired to the Instrument Cluster (MIC) to control Warning Indicator (SRS indicator). When DTCs becomes activate, the ACM illuminates the Warning Indicator by pulling the indicator circuit low. The SRS indicator is the only point at which the customer can observe symptoms of a system malfunction.

As part of the system test the ACM illuminates the Warning Indicator on for 4.0 second bulb test. After the lamp check, if the indicator turns off, it means that the ACM has checked the system and found it to be free of discernible malfunctions.