Diagnostic System Check

Diagnostic Chart:

CAUTION: IN ORDER TO AVOID DEPLOYING THE AIR BAG WHEN TROUBLESHOOTING THE SIR SYSTEM, USE ONLY THE EQUIPMENT SPECIFIED AND THE INSTRUCTIONS GIVEN. FAILURE TO USE THE SPECIFIED EQUIPMENT AS INSTRUCTED COULD CAUSE AIR BAG DEPLOYMENT; PERSONAL INJURY TO YOU OR
SOMEONE ELSE, OR UNNECESSARY SIR SYSTEM REPAIRS.

DIAGNOSTIC SYSTEM CHECK
The diagnostic procedures used in this section are designed to find and repair SIR system malfunctions. To get the best results, it is important to use the diagnostic charts and follow the sequence listed below.

PERFORM THE SIR DIAGNOSTIC SYSTEM CHECK
A. The "SIR Diagnostic System Check" must be the starting point of any SIR diagnostics. The "SIR Diagnostic System Check" checks for the proper Air Bag telltale operation, the ability of the SDM to communicate through the serial data line, and whether any SIR diagnostic trouble codes exist.
B. Refer to the proper diagnostic chart as directed by the "SIR Diagnostic System Check". The "SIR Diagnostic System Check" will lead you to the correct chart to diagnose any SIR faults. Bypassing these procedures may result in extended diagnostic time, incorrect diagnosis and incorrect parts replacement.
C. Repeat the "SIR Diagnostic System Check" after any repair or diagnostic procedures have been performed. Performing the "SIR Diagnostic System Check" after all repair or diagnostic procedures will ensure that the repair has been made correctly and that no other malfunctions exist.

CIRCUIT DESCRIPTION
When ignition is switched ON, system voltage is applied to terminal A1 of the SDM from the IGN 1 fuse in the UHFB. 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 B1OOO, 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.