Chart B - Air Bag Warning Light Comes On Steady: Description

When ignition switch is first turned on, IGNITION 1 voltage is applied from GAUGES fuse to REDUNDANT INDICATOR IGNITION 1 terminal B2 and to AIR BAG warning light which is connected to SIR INDICATOR, terminal B1. AIR BAG fuse applies system voltage to IGNITION 1 inputs, terminals A9 and A10. DERM responds by flashing AIR BAG warning light 7 times. If IGNITION 1 is outside of normal operating voltage range, AIR BAG warning light will illuminate with no Diagnostic Trouble Codes (DTCs) set.

When engine is cranked, battery voltage is applied from CRANK fuse to DERM at CRANK input. DERM responds by grounding SIR INDICATOR output until battery voltage is removed from CRANK input. This results in AIR BAG warning light being on during cranking. After cranking, DERM will flash AIR BAG warning light 6 times.

1. Open AIR BAG fuse would cause AIR BAG warning light to come on steady.
2. Disconnected DERM harness connector will cause warning light to come on steady via shorting bar from terminal A1 to terminal B1.
3. Checks for an open in ground circuit to DERM.
4. Checks for an open in IGNITION 1 circuit to ground.
5. Checks for a short from SIR INDICATOR circuit to ground.
6. Checks for a short from CRANK input circuit to voltage.
7. Checks whether short to ground caused CRANK fuse to open.
8. Checks whether short to ground is caused by malfunctioning dual pole arming sensor or short in wiring.

Fig 1: Chart B - Air Bag Warning Light Comes On Steady

Courtesy of GENERAL MOTORS CORP.