Chart D - Air Bag Warning Light Does Not Come On Steady During Crank: 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. Checks whether malfunction is caused by open CRANK fuse.
2. Checks for proper signal to CRANK input during cranking.
3. Checks whether lack of correct crank signal is caused by open CRANK input circuit or an open power feed to CRANK fuse.
4. Checks whether CRANK fuse is open due to short to ground in CRANK input circuit.
5. Checks whether short to ground is in wiring harness or DERM.

Fig 1: Chart D - Air Bag Warning Light Does Not Come On Steady During Crank

Courtesy of GENERAL MOTORS CORP.