Circuit Description

CIRCUIT DESCRIPTION

SIRS Schematic:

When ignition is switched ON, system voltage is applied to terminal 1 of the SDM from the AIR BAG fuse in the IPFB. The SDM self-checks the system voltage and deployment loop while the I/P cluster performs a bulb check by flashing the AIR BAG telltale seven times. If a diagnostic trouble code is detected, the SDM will command the I/P cluster to light the AIR BAG telltale when the bulb check is complete. If no DTC is detected, the telltale will not light. The SDM communicates with the I/P cluster on circuit 1807.

DIAGNOSTIC AIDS

NOTE: 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.