Circuit Description
The ignition switch supplies battery voltage to the AIR BAG indicator using the F13 fuse. The AIR BAG indicator is controlled by the sensing and diagnostic module (SDM) via universal asynchronous receiver transmitter (UART) data. When the ignition switch is first turned to the ON position, the SDM responds by illuminating the AIR BAG indicator for approximately 6 seconds while performing diagnostic tests on the SIR system.
Diagnostic Aids
Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.
The following are possible causes of the malfunction:
| • | An instrument cluster malfunction |
| • | An internal SDM malfunction |
If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views | |||
1 | Did you perform a Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the ABS indicator illuminate? | Go to Step 3 | Go to Diagnostic Starting Point - Instrument Panel, Gages and Console |
With the scan tool, command the Air Bag indicator On. Does the Air Bag indicator illuminate? | Go to Step 4 | Go to Diagnostic Starting Point - Instrument Panel, Gages and Console | |
4 | Replace the sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | Go to Step 5 | -- |
5 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
