Table A SIR Sensing & Diagnostic Module Integrity Check

CAUTION: Be careful when you handle a Sensing & 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.
^ Point the arrow on the SDM toward the front of the vehicle.
^ Tighten all of the SDM fasteners and SDM bracket fasteners to the specified torque value.
Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs.

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

CIRCUIT DESCRIPTION

When the ignition switch is first turned to RUN, Ignition 1 voltage is applied from the SIR Fuse to the inflatable restraint Sensing and Diagnostic Module (SDM) at the Ignition 1 input terminal 3. Ignition 1 is also applied to the Instrument Panel Cluster (IPC). The IPC responds by flashing the AIR BAG warning lamp seven times. At this time the SDM performs Power-ON tests followed by Resistance Measurement Test and Continuous Monitoring tests. If the SDM detects no malfunctions, the SDM commands the IPC to turn the warning lamp OFF. If the SDM detects a malfunction, the SDM commands the IPC to turn the warning lamp ON. The SDM will clear current diagnostic trouble codes and move them to a history file when:
^ The malfunction is no longer detected.
^ The ignition switch is cycled. This does not include DTCs B1151, B1152, B1153, and B1171. DTC B1151 and B1153 can only be cleared using a scan tool Clear Codes command. DTCs B1152 and B1171 may not clear after a Clear Codes command is issued.

TABLE TEST DESCRIPTION

Numbers below refer to step numbers on the diagnostic table.
2. This test confirms a current malfunction. If no current malfunction is occurring (History DTC set) the Diagnostic Aids for the appropriate diagnostic trouble code should be referenced. The SDM should not be replaced for a History DTC other than DTC B1171.
3. This test checks for a malfunction introduced into the SIR system during the diagnostic process. It is extremely unlikely that a malfunctioning SDM would cause a new malfunction to occur during the diagnostic process.
4. When you have found all circuitry outside the SDM to operate properly as indicated by the appropriate diagnostic table, then and only then should you replace the SDM.