Diagnostic System Check

CIRCUIT DESCRIPTION
When the ignition switch is first turned "On," system voltage is applied from the AIR BAG fuse to the Sensing and Diagnostic Module (SDM) at the "IGN 1" terminal "A1." The SDM responds by flashing the AIR BAG telltale lamp seven times while performing tests on the SIR system. System voltage is also applied from the "IGN 1" fuse through the cluster at the "IGN 1" terminals "H" and "F" to the SDM at the AIRBAG input at terminal "A9." The SDM responds by grounding the AIRBAG output and flashes the AIR BAG telltale lamp.

DIAGNOSTIC AIDS

NOTICE: The order in which diagnostic trouble codes (DTCs) are diagnosed is very important. Failure to diagnose the DTCs in the order specified may result in extended diagnostic time, incorrect diagnosis, and incorrect parts replacement.

CURRENT CODES
Current diagnostic trouble codes (DTCs) indicate faults that were present since the last ignition cycle. Current codes can be viewed on the Scan tool.

HISTORY CODES
History DTCs indicate faults that may not be currently detected, but have been present in past ignition cycles. History codes can be viewed on the Scan tool in the history diagnostic trouble code table. History Codes B0051, B0053, or B1000, cannot be cleared from the SDM.

INTERMITTENT CODES
If a fault occurs intermittently, the first occurrence will result in a stored history DTC. If the same fault occurs twice within 125 ignition cycles, the AIR BAG telltale will be turned On and will remain On until the vehicle is serviced. The second occurrence fault will be stored as a current DTC.