Table A SIR Sensing & Diagnostic Module Integrity Check

Wiring Diagram:

WARNING: During service procedures, be very careful when handling a Sensing and Diagnostic (SDM) Module. Never strike or jar the SDM. Never power up the SIR system when the SDM is not rigidly attached to the vehicle. All SDM mounting bracket fasteners must be carefully torqued and the arrow must be pointing toward the front of the vehicle to ensure proper operation of the SIR system. The SDM could be activated when powered while not rigidly attached to the vehicle which could cause deployment and result in personal injury.

This chart assumes that the "SIR Diagnostic System Check" and either a symptom chart or a diagnostic trouble code chart diagnosis have been performed. When all circuitry outside the Sensing and Diagnostic Module (SDM) has been found to operate properly, as indicated by the appropriate diagnostic chart, and the symptom or DTC remains current, the following diagnostic procedures must be performed to verify the need for SDM replacement.

NOTICE: Perform "SIR DIAGNOSTIC SYSTEM CHECK" before proceeding with this chart. SIR Diagnostic System Check

CIRCUIT DESCRIPTION
When the SDM recognizes "Ignition 1" voltage, applied to terminal A10 is greater than approximately 9 volts, the AIR BAG telltale lamp is flashed seven times to verify operation. During this time the SDM performs "turn-on" tests (including current source diagnostics) followed by "continuous monitoring" tests. When a malfunction is detected the SDM sets an active diagnostic trouble code and illuminates the AIR BAG telltale lamp. At power-up with the existing current DTC code, the AIR BAG telltale lamp will flash more than seven times and then remain on steady. The SDM will clear active diagnostic trouble codes and move them to a history file when a malfunction is no longer detected and/or the ignition switch is cycled, except for DTC 18, 24, 51, 53 and 71. If DTC 18, 24, 51, 53 or 71 are set, the SDM must be replaced.

CHART TEST DESCRIPTION
The numbers below refer to the step numbers listed on the diagnostic chart.
Step 1. This step verifies that the fault is still occurring.
Step 2. This step verifies that the trouble codes have not changed.
Step 3. This test checks if codes reset after being cleared.