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.
Diagnostic Procedures
2004 Oldsmobile Bravada AWDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 GMC Savana and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
- Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Is the cooling system low on coolant? If yes, locate and repair source of coolant loss and refill system. If no, go to next step.
- Turn OFF the ignition. Disconnect the ECT sensor. Connect a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor. Turn ON the ignition, with the engine OFF. Observe the ECT sensor temperature with a scan tool. Does the scan tool indicate that the ECT sensor temperature is more than 280°F (138°C)? If yes, go to step 7. If no, go to next step.
- Turn OFF the ignition. Disconnect the ECT sensor. Connect a 3 amp fused jumper wire between the signal circuit of the ECT sensor and a known-good ground. Turn ON the ignition, with the engine OFF. Observe the ECT sensor temperature with a scan tool. Does the scan tool indicate that the ECT sensor temperature is more than 280°F (138°C)? If yes, go to next step. If no, go to step 6.
- Test the ECT sensor low reference circuit for a high resistance or an open. Repair the circuit as necessary. After repairs, go to step 10.
- Test the ECT sensor signal circuit for a high resistance or an open. Repair the circuit as necessary. After repairs, go to step 10.
- Remove the ECT sensor. Suspend the ECT sensor and a thermometer in a pan of water. Place the pan on a burner or hot plate. Test the resistance of the ECT sensor through 50-194°F (10-90°C). See appropriate SENSOR OPERATING RANGE CHARTS article. Does the resistance and temperature closely match the Temperature vs Resistance Table? If yes, go to next step. If no, go to step 9.
- Install the ECT sensor. After installation, diagnose thermostat.
- Replace the ECT sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
- Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
- Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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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.