Air Bag Control Module: Description and Operation

Notice: Do not open the DERM case for any reason. Touching the connector pins, or the soldered components may cause electrostatic discharge damage. Replacement is the only way to repair a malfunctioning DERM.

The DERM performs the following functions in the SIR system:
1. Energy Reserve: The DERM maintains a 36 Volt Loop Reserve (36 VLR) energy supply in order to provide deployment energy when the voltage is low or lost in a frontal crash.
2. Malfunction Detection: The DERM performs diagnostic monitoring of the SIR system electrical components.
3. Malfunction Recording: The DERM provides SIR system diagnostic trouble code information through a scan tool.
4. Driver Notification: The DERM controls the AIR BAG warning lamp. This warns the vehicle driver of SIR system malfunctions.
5. Frontal Crash Recording: The DERM records the SIR system status during a frontal crash.

The DERM is connected to the SIR wiring harness by a 24-way connector. When the DERM harness connector is disconnected, a shorting bar connects the AIR BAG warning lamp to ground. This causes the AIR BAG warning lamp to light up whenever the ignition switch is at the RUN or the START position.