Air Bag Control Module: Description and Operation

DERM

CAUTION: Do not open the DERM case for any reason. touching the connector pins or soldered components may cause electrostatic discharge damage. repair of a malfunctioning derm is by replacement only.

The DERM is designed to perform the following functions in the SRS:

1. Energy Reserve-The DERM maintains two 36-Volt Loop Reserve(36VLR) energy supplies to provide deployment energy when the vehicle voltage is low or lost in a frontal crash.
2. Malfunction Detection-The DERM performs diagnostic monitoring of SRS electrical components.
3. Malfunction Recording-The DERM provides SRS diagnostic trouble code information through a scan tool.
4. Driver Notification-The DERM warns the vehicle driver of SRS malfunctions by controlling the "AIR BAG" warning lamp.
5. Frontal Crash Recording-The DERM records the SRS status during a frontal crash.

The DERM is connected to the SRS wiring harness by a 24-way connector. This harness connector uses a shorting clip across certain terminals in the contact area. This shorting clip connects the "AIR BAG" warning lamp to ground when the DERM harness connector is disconnected. This will cause the "AIR BAG" warning lamp to come "ON" steady whenever the ignition switch is at the RUN, BULB TEST or START positions with the DERM disconnected.