Diagnostic System Check

Circuit Description
The ignition switch uses the AIR BAG Fuse for supplying Ignition 1 voltage to the Inflatable Restraint Sensing and Diagnostic Module (SDM) at terminal 8. When you first turn the ignition switch to the ON position, the SDM responds by flashing the AIR BAG warning lamp seven times. Then the SDM turns the lamp Off, while performing tests on the SIR system.

Diagnostic Aids
Diagnosing DTCs in the correct order is very important. Failure to diagnose DTCs in the order specified may result in the following:
^ Extended diagnostic time.
^ Incorrect diagnosis.
^ Incorrect parts replacement.

Test Description
The numbers below refer to the step numbers on the diagnostic system check table.
1. This step confirms that the AIR BAG warning lamp should flash seven times after you first turn the ignition to the ON position.
2. The AIR BAG warning lamp indicates improper operation. This step differentiates between a warning lamp which stays in the ON position and a warning lamp that does not come ON.
3. This step confirms that the AIR BAG warning lamp should turn OFF after flashing seven times.
4. This step determines whether the SDM is flashing DTC 12.
6. This step checks for proper operation of the serial data line.
7. This step identifies the stored diagnostic trouble codes and tells whether they are current or history.
8. This step checks for the proper operation of the serial data line. This step also identifies any stored history diagnostic trouble codes.