Air Bag Warning Lamp Circuit Malfunction

Circuit Description
The AIR BAG warning lamp is controlled by the supplemental restraint sensing and diagnostic module (SDM) via Class 2 serial data. When the ignition switch is first turned to the RUN position, the SDM performs tests to diagnose critical malfunctions within itself. The SDM then commands the AIR BAG warning lamp OFF after it has flashed seven times.

Diagnostic Aids
- If Ignition 1 voltage is outside of the normal operating voltage range (9 - 16 volts), the AIR BAG warning lamp will come ON solid with no DTC's set.
- The loss of serial data communication between the supplemental restraint sensing and diagnostic module (SDM) and the instrument panel cluster (IPC), will cause the AIR BAG warning lamp to come ON solid. Refer to DTC U1001-U1254 Lost Communication with XXX in Data Link Communications.

Steps 1 - 4:

Steps 5 - 9:

Steps 10 - 15:

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.

3. This step checks to see if the AIR BAG warning lamp flashes seven times when the ignition switch is first turned to the RUN position.
5. This step checks to see if DTC U1088 is present in the instrument panel cluster (IPC).
6. This step checks to see if the AIR BAG warning lamp is being commanded ON.
7. This step checks to see if ignition 1 voltage to the SDM is more than 9 V.
8. This step determines if ignition 1 voltage to the SDM is more than 16 V or if there is a malfunctioning SDM.
9. This step inspects the SDM wiring harness connector for corrosion or damage.
11. Tests for an open or high resistance in the ignition 1 voltage circuit and also for a high resistance in the power feed circuit to the AIR BAG Fuse.