SIR Diagnostic System Check

SIR DIAGNOSTIC SYSTEM CHECK

CAUTION: To avoid deployment when troubleshooting the SIR system, do not use electrical test equipment such as a battery powered or AC powered voltmeter, ohmmeter, etc., or any type of electrical equipment other than that specified. Do not use a non-powered probe type tester. Instructions must be followed carefully, otherwise personal injury may result.


NOTICE: If the vehicle interior has been exposed to extensive water intrusion, such as water leaks, window left open, driving through high water and so forth, the Sensing and Diagnostic Module (SDM) and the SDM connector may need to be replaced. With the ignition "OFF," inspect the area under the RH front seat and the area around the SDM, including the carpet. If any significant soaking or evidence of significant soaking is detected, the water must be removed, water damage repaired and the SDM and the SDM connector MUST he replaced. Before attempting any of these repairs, the SIR system must be disabled. Refer to "ON-VEHICLE SERVICE" for instructions on how to disable the SIR system and replace the SDM and SDM connector.

The diagnostic procedures used 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.

A. PERFORM THE "SIR DIAGNOSTIC SYSTEM CHECK." The "SIR Diagnostic System Check" must he the starting point of any SIR diagnostics. The "SIR Diagnostic System Check" checks for proper "AIR BAG" indicator operation, the ability of the SDM to communicate through the "Serial Data" line and whether 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 system malfunctions. 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 the ignition switch is first turned to "RUN," "Ignition 1" voltage is applied from the "AIR BAG" fuse to the SDM at the "Ignition 1" input terminal "10." The SDM responds by flashing the "AIR BAG" indicator seven times then turning it "OFF" while performing tests on the SIR system.


NOTES ON SYSTEM CHECK CHART:

1. The "AIR BAG" indicator should flash seven times after the ignition is first turned to "RUN."

2. After the "AIR BAG" indicator flashes seven times it should turn "OFF."

3. This test will determine whether history diagnostic trouble codes are stored and, if so, identify them.

4. Improper operation of the "AIR BAG" indicator is indicated. This test differentiates an indicator stays "ON" condition from an indicator does not come "ON" condition.

5. This test will identify the stored diagnostic trouble codes and whether they are current or history.


DIAGNOSTIC AIDS

The order in which diagnostic trouble codes 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.