Air Bag Control Module: Description and Operation

SENSING AND DIAGNOSTIC MODULE (SDM)






CAUTION: Be careful when you handle a sensing and diagnostic module (SDM). Do not strike or jolt the SDM. Before applying power to the SDM:
- Remove any dirt, grease, etc. From the mounting surface.
- Position the SDM horizontally on the mounting surface.
- Tighten all of the SDM fasteners and SDM bracket fasteners to the specified torque value.

Failure to follow the correct procedures could cause air bag deployment, personal injury, or unnecessary SIR system repairs.

The sensing and diagnostic module (SDM) is located on the floor beneath the floor console assembly. The SDM performs the following functions:
- Monitors the supplemental inflatable restraints (SIR) electrical components and sets a DTC when malfunction is detected
- Records any faults that are discovered
- Displays SIR DTCs and system status information when connected to a scan tool
- Illuminates the Air Bag indicator to alert the driver to any fault
- Provides a reserve power source to deploy the air bags and pretensioners if an accident has disabled the normal power source
- Monitors vehicle velocity changes to detect frontal impacts, which are severe enough to warrant deployment
- Causes current to flow through the air bag modules and pretensioner to cause deployment if a frontal impact of sufficient force is detected

The SDM contains no user-serviceable parts.