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 RWDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.NOTE: If any other DTCs are set, diagnose affected DTCs before proceeding with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
- Ensure engine is at normal operating temperature. Operate engine at greater than 1200 RPM for 2 minutes. Using scan tool, observe O2S 1 voltage. Does the scan tool indicate O2 voltage varying outside the specified value of 400-500 millivolts? If yes, go to next step. If no, go to step 4.
- Operate vehicle within Failure Records conditions. Does the scan tool indicate this DTC failed this ignition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
- Check for exhaust leak or improperly installed O2S 1. Check for damaged wiring. Did you find and correct the condition? If yes, go to step 13. If no, go to next step.
- Turn ignition off. Disconnect the O2S. Turn ON the ignition. Measure the voltage on the O2S high signal circuit, PCM side, using a Digital Multimeter (DMM) that is connected to a good ground. Does the voltage measure about 450 millivolts? If yes, go to next step. If no, go to step 8.
- Jumper the high signal circuit to the low signal circuit, PCM side. With a scan tool, observe O2S voltage parameter. Does the scan tool indicate O2S voltage at or about 0 millivolts? If yes, go to step 9. If no, go to next step.
- Test the low signal circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 13. If no, go to step 11.
- Test the high signal circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 13. If no, go to step 11.
- Test for poor connections at the O2S. Did you find and correct the condition? If yes, go to step 13. If no, go to next step.NOTE: Determine the cause of contamination before replacing the sensor.
- Check for fuel contamination or improper use of RTV sealant. Repair as necessary. Replace O2S 1. After replacing sensor, go to step 13.
- Check for poor connections at PCM. Repair as necessary. Did you find and correct the condition? If yes, go to step 13. If no, go to next step.
- Replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After replacing PCM, go to next step.
- Turn ignition on, with engine off. Using scan tool, clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
- With a scan tool, observe the stored information, Capture Info. 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.