SIR Diagnostic System Check

CIRCUIT DESCRIPTION

When the ignition switch is first turned to "ON," "Ignition 1" voltage is applied from the "AIR BAG-IG" fuse to the SDM at the "Ignition 1" input terminal "8." The SDM responds by flashing the "AIR BAG" warning lamp seven times while performing tests on the SIR system.

NOTES ON SYSTEM CHECK CHART

Numbers below refer to circled numbers on the diagnostic chart.

1. The "AIR BAG" warning lamp should flash seven times after ignition is first turned to "ON."

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

3. This test checks for the proper operation of the "Serial Data" line. This test will also determine whether history diagnostic trouble codes are stored and, if so, identify them.

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

5. This test determines whether a current DTC exists or a false diagnostic request condition is present.

6. This test checks for proper operation of the "Serial Data" line. This test will also 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 diagnostic trouble codes in the order specified may result in extended diagnostic time, incorrect diagnosis and incorrect parts replacement.