Test Notes

Normal Operation
The air bag indicator is designed to illuminate for six (+/- two) seconds when the ignition key is turned to the RUN position. This initial six seconds of air bag indicator illumination is considered normal operation and is called prove out of the air bag diagnostic monitor. If the air bag diagnostic monitor detects any faults in the air bag system following prove out, it will flash the air bag indicator a series of times to indicate the Diagnostic Trouble Code (DTC) that has been detected. If the air bag indicator comes on when the key is turned to the ON position and stays on for more than eight seconds continuously, then a fault exists in the air bag indicator circuit.

The air bag diagnostic monitor incorporates a solid state circuit that shorts the air bag indicator line (circuit 31S-MA14 [BK/UN]) to ground to turn on the air bag indicator. When the gray air bag diagnostic monitor harness connector C20a is disconnected from the air bag diagnostic monitor, a shorting bar within the harness connector shorts pin C20a-4, circuit 31S-MA14 (BK/UN) and pin C2Oa-5, circuit 91-MA10a (BK/RD) together, causing a continuous illumination. Because the shorting bar makes a continuous connection between pins C20a-4, circuit 31S-MA14 (BK/ON) and C2Oa-5, circuit 91-MA10a (BK/RD) when the connector is disconnected, the air bag indicator will not flash. Instead the air bag indicator will be illuminated continuously.

If the computer within the air bag diagnostic monitor fails to "boot up" with the key ON, the air bag indicator driver circuit will automatically turn the air bag indicator on continuously, indicating a problem in the air bag diagnostic monitor or at the gray air bag diagnostic monitor C20a.

Possible Causes
Continuous illumination of the air bag indicator can be caused by the following:
1. A disconnected or poorly connected air bag diagnostic monitor may not push the shorting bar between pins C20a-4, circuit 31S-MA14 (BK/GN) and C20a-5, circuit 91-MA10a (BK/RD) into its fully retracted position. This shorts the air bag indicator line to ground and causes the air bag indicator to illuminate continuously.
2. Shorted air bag indicator wiring.
3. A damaged air bag diagnostic monitor.