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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 11 (SUPPLEMENTAL INFLATABLE RESTRAINT SYSTEM)DIAGNOSTIC TESTSDTC B0029: PASSENGER DEPLOYMENT LOOP OPENDIAGNOSTIC PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Procedure
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2000 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.
- If SIR Diagnostic System Check has been performed, go to next step. If SIR Diagnostic System Check has not been performed, go to SIR DIAGNOSTIC SYSTEM CHECK .
- Disconnect passenger side impact air bag Yellow 2-pin connector under passenger seat. See Figure. Check terminals for corrosion, damage and poor connections. If damage is evident, go to next step. If damage is not evident, go to step 4.
- Replace harness. Go to step 14.
- Reconnect passenger side impact air bag Yellow 2-pin connector. Ensure CPA clip is installed correctly. Turn ignition on. Using scan tool, check for SIR DTCs. If DTC B0029 is retrieved, go to next step. If DTC B0029 is not retrieved, see DIAGNOSTIC AIDS.
- Turn ignition off. Disconnect passenger side impact air bag Yellow 2-pin connector under passenger seat. See Figure. Install SIR Driver/Passenger Load Tool (J-38715-A) to harness side of connector. Turn ignition on. Using scan tool, check for SIR DTCs. If DTC B0029 is retrieved, go to step 7. If DTC B0029 is not retrieved, go to next step.
- Turn ignition off. Replace passenger side impact air bag module. See AIR BAG MODULES under REMOVAL & INSTALLATION. Go to step 14.
- Turn ignition off. Remove SIR Driver/Passenger Load Tool (J-38715-A) from harness connector. Disconnect SDM harness connector. Inspect SDM terminals No. B3 and B4 for proper connections. If connections are okay, go to step 9. If connections are not okay, go to next step.
- Replace or repair SDM harness connector. Go to step 14.
- Using Digital Multimeter (J-39200), measure resistance of passenger side frontal high circuit 2103 between SDM harness connector terminal No. B4 and terminal "A" of passenger-side air bag 2-pin Yellow connector. See Figure & Figure . If resistance is less than 0.5 ohms, go to step 11. If resistance is 0.5 ohms or more, go to next step.
- Repair open or high resistance condition in circuit 2103. Go to step 14.
- Using Digital Multimeter (J-39200), measure resistance of passenger side low circuit 2104 between SDM harness connector terminal No. B3 and terminal "B" of passenger-side air bag 2-pin Yellow connector. See Figure & Figure . If resistance is less than 0.5 ohms, go to step 13. If resistance is 0.5 ohms or more, go to next step.
- Repair open or high resistance condition in circuit 2104. Go to step 14.
- Replace SDM. See SENSING & DIAGNOSTIC MODULE (SDM) under REMOVAL & INSTALLATION. Go to next step.
- Reconnect all SIR components. Ensure that all components are properly mounted. Clear all SIR DTCs. Go to SIR DIAGNOSTIC SYSTEM CHECK .
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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.