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 does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. 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.
- Install a scan tool. Raise the drive wheels. Start the engine. Disable the traction control system, if equipped. Shift the transmission into third gear. Slowly release the clutch. With the drive wheels rotating, does the vehicle speed increase with drive wheel speed increase? If yes, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
- Turn OFF the ignition. Shift the transmission into Neutral. Back probe the VSS buffer module ignition feed circuit with a test light connected to ground. Is the test light ON? If yes, go to next step. If no, go to step 7 .
- Back probe the VSS buffer module ignition feed circuit to the ground circuit with a test light. Is the test light ON? If yes, go to next step. If no, go to step 8 .
- Back probe the VSS buffer module at the VSS input circuit (C7) to the other VSS input circuit (C12) with a Digital Multimeter (DMM) on the AC scale. Place the transmission in any drive range with the drive wheels rotating. Does the voltage increase on the DMM with drive wheel increase? If yes, go to next step. If no, go to step 9 .
- Does the scan tool display a trans output speed (MPH) increase with drive wheel increase? If yes, go to step 12 . If no, go to step 11 .
- Repair the open in the ignition feed circuit. After repairs, go to step 17 .
- Repair the open in the ground circuit. After repairs, go to step 17 .
- Test the complete VSS input circuit for an open or short to ground. Was a repair performed? If yes, go to step 17 . If no, go to next step.
- Test the VSS connector for an open or high resistance condition. If a condition is found, repair the condition as necessary. Was a condition found? If yes, go to step 17 . If no, go to step 14 .
- Back probe the VSS buffer module at the VSS output circuit (C15) with a DMM connected to ground. Place the transmission in any drive range with the drive wheels rotating. Is there voltage present? If yes, go to next step. If no, go to step 15 .
- Test the VSS output circuit for an open or short to ground. Was a repair performed? If yes, go to step 17 . If no, go to next step.
- Test the VSS output circuit connections at the PCM for an open or high resistance condition. Was a repair performed? If yes, go to step 17 . If no, go to step 16 .
- Replace the vehicle speed sensor. After repairs, go to step 17 .
- Replace the VSS Buffer module. After repairs, go to step 17 .
- Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Using the scan tool, clear the DTCs. Start the engine and idle at normal operating temperature. Select DTC, Specific, then enter the DTC number which was set. Operate the vehicle within the Conditions for Setting DTC, until the scan tool indicates the diagnostic Ran. Does the scan tool indicate the diagnostic Passed? If yes, system is okay. If no, go to step 2 .
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.