Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC2004ENVOY 2WD L6-4.2L VIN SREPAIR AND DIAGNOSISRESTRAINTS AND SAFETY SYSTEMSAIR BAG SYSTEMSTESTING AND INSPECTIONSYMPTOM RELATED DIAGNOSTIC PROCEDURESAIR BAG INDICATOR CIRCUIT MALFUNCTION
2004 GMC Envoy 2WD L6-4.2L VIN S
AIR BAG Indicator Circuit Malfunction
2004 GMC Envoy 2WD L6-4.2L VIN SSECTION AIR BAG Indicator Circuit Malfunction
AIR BAG INDICATOR CIRCUIT MALFUNCTION
CIRCUIT DESCRIPTION
The AIR BAG warning lamp is controlled by the inflatable 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 DTCs set.
- The loss of serial data communication between the inflatable 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 in Data Link Communications. Testing and Inspection
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.
4. This step checks to see if DTC U1088 is present in the instrument panel cluster (IPC).
5. This step checks to see if the AIR BAG warning lamp can be commanded ON.
6. This step checks to see if ignition 1 voltage to the SDM is more than 9 V.
7. This step determines if ignition 1 voltage to the SDM is more than 16 V or if there is a malfunctioning SDM.
8. This step inspects the SDM wiring harness connector for corrosion or damage.
10. Tests for an open or high resistance in the ignition 1 voltage circuit between the SDM and the SIR fuse.
12. Tests for an open or high resistance in the ignition 1 voltage circuit to the SIR fuse.
14. Tests for an open or high resistance in the SDM ground circuit or if there is a malfunctioning SDM.
CIRCUIT DESCRIPTION
The AIR BAG warning lamp is controlled by the inflatable 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 DTCs set.
- The loss of serial data communication between the inflatable 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 in Data Link Communications. Testing and Inspection
TEST DESCRIPTION
Steps 1-10:
Steps 11-18:
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.
4. This step checks to see if DTC U1088 is present in the instrument panel cluster (IPC).
5. This step checks to see if the AIR BAG warning lamp can be commanded ON.
6. This step checks to see if ignition 1 voltage to the SDM is more than 9 V.
7. This step determines if ignition 1 voltage to the SDM is more than 16 V or if there is a malfunctioning SDM.
8. This step inspects the SDM wiring harness connector for corrosion or damage.
10. Tests for an open or high resistance in the ignition 1 voltage circuit between the SDM and the SIR fuse.
12. Tests for an open or high resistance in the ignition 1 voltage circuit to the SIR fuse.
14. Tests for an open or high resistance in the SDM ground circuit or if there is a malfunctioning SDM.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.