Seville STS V8-4.6L VIN 9 (1998)
Air Bag Control Module: Description and Operation
Inflatable Restraint Side Impact Sensing/Diag Module (SISM)
The inflatable restraint side impact sensing module (SISM) performs the following functions in the air bag system:
^
Energy Reserve - The SISM maintains 23 Volt Loop Reserve (23VLR) energy supplies to provide deployment energy. Ignition voltage can
provide deployment energy if the 23 Volt Loop Reserves malfunction.
^
Side Impact Crash Detection - Each SISM monitors vehicle velocity changes to detect side impact crashes that are severe enough to warrant
deployment.
^
Side Impact Air Bag Deployment - During a side impact crash of sufficient force, the SISM will cause enough current to flow through the
respective side air bag inflator module to deploy the side impact air bag.
^
Side Air Bag System Status Communication - The inflatable restraint sensing and diagnostic module (SDM) monitors a diagnostic line from
each SISM. Both SISMs communicate the status of the side impact air bag system to the SDM over these diagnostic lines.
The SISM connects to the air bag wiring harness using a 5-way connector.
The SISM receives power whenever the ignition switch is in the ACC or ON positions. The SISM and the SDM are powered by the same fuse.
