SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSOLDSMOBILE2004BRAVADA AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 85 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 8.1L)DIAGNOSTIC TESTSDTC P1518: TAC MODULE SERIAL DATA FAULTDIAGNOSTIC PROCEDURES
2004 Oldsmobile Bravada AWD

Diagnostic Procedures

2004 Oldsmobile Bravada AWDSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 13 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 GMC Savana Special, 2002 GMC Savana Camper Special, and 2002 GMC Savana. However, it is still accessible from the selected car via links, so may be relevant.
  1. 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.
  2. Turn ON the ignition, with the engine OFF. Remove the cover from the underhood electrical center. With a test lamp connected to ground, test both sides of the ETC fuse. Does the test lamp illuminate on at least 1 side of the fuse? If yes, go to next step. If no, diagnose ignition relay. See appropriate SYSTEM & COMPONENT TESTING article.
  3. Turn OFF the ignition With a test lamp connected to ground, test for voltage at the ETC fuse. Does the test lamp illuminate? If yes, go to step  22. If no, go to next step.
  4. Connect a scan tool. Is DTC P0604 also set? If yes, see DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681 & P1683: PCM MEMORY . If no, go to next step.
    5. NOTE: If the Driver Information Center is displaying Reduced Engine Power, go to next step.
  5. Start the engine. Increase the engine speed to 3000 RPM, if possible. Monitor the Diagnostic Trouble Code (DTC) Info option using the scan tool. Does the scan tool indicate this DTC failed this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  6. Turn OFF the ignition. Disconnect the throttle actuator motor harness connector. Turn ON the ignition, with the engine OFF. With a Digital Multimeter (DMM), test for voltage at both throttle actuator motor control circuits. Does the DMM indicate voltage on both circuits above 8 V? If yes, go to step  12. If no, go to next step.
  7. Turn OFF the ignition. With a DMM, test both throttle actuator motor control circuits for continuity to ground. Does the DMM indicate continuity to ground? If yes, go to step  10. If no, go to next step.
  8. Turn OFF the ignition. Remove the ETC fuse. With a DMM, test the TAC side of the fuse terminal for continuity to ground. Does the DMM indicate continuity to ground? If yes, go to next step. If no, go to step  11.
  9. Disconnect the TAC module 16-way harness connector. With a DMM, test the TAC side of the fuse terminal for a short to ground. Did you find and correct the condition? If yes, go to step  28. If no, go to step  24.
  10. Disconnect the TAC module 16-way harness connector. With a DMM, test the throttle actuator motor control circuits for a short to ground at the TAC module 16-way harness connector. Did you find and correct the condition? If yes, go to step  28. If no, go to step  24.
  11. Turn OFF the ignition. Disconnect the TAC module 16-way harness connector. With a DMM, test the TAC module ignition feed circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  28. If no, go to step  24.
  12. Turn OFF the ignition. Disconnect the TAC module 16-way connector. Turn ON the ignition, with the engine OFF. With a DMM, test for a short to voltage at both throttle actuator motor control circuits. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  13. Turn OFF the ignition. Disconnect the TAC module 10-way harness connector. With a DMM, test for a short between each throttle actuator motor control circuit and all other TAC module circuits. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  14. With a DMM, test for an open or high resistance in the TAC module ground circuit. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  15. With a DMM, test for voltage on the serial data circuits at the TAC module 16-way harness connector. Does the DMM indicate voltage is 0-4.5 V for both circuits? If yes, go to next step. If no, go to step  18.
  16. Turn OFF the ignition. With a DMM, test both serial data circuits at the TAC module 16-way harness connector for continuity to ground. Does the DMM indicate OL for both circuits? If yes, go to step  20. If no, go to next step.
  17. Disconnect the PCM connector containing the TAC module serial data circuits. With a DMM, test both serial data circuits at the TAC module 16-way connector for a short to ground. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  18. With a DMM, test for a short between both serial data circuits and all other circuits at the PCM and TAC module harness connectors. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  19. With a DMM, test for a short to voltage on both serial data circuits at the TAC module 16-way connector. Did you find and correct the condition? If yes, go to step  28. If no, go to step  25.
  20. Disconnect the PCM connector that contains the TAC module serial data circuits. With a DMM, test each serial data circuit between the TAC module 16-way harness connector and the PCM harness connector for an open or high resistance. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  21. Reconnect the PCM. Turn ON the ignition. With a DMM, test for voltage on the serial data circuit at the TAC module 16-way harness connector. Does the DMM indicate voltage at 0 V? If yes, go to step  25. If no, go to step  24.
  22. Turn OFF the ignition Disconnect the 16-way TAC module harness connector. Test the TAC module ignition feed circuit for a short to battery voltage. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  23. Turn ON the ignition. Test both TAC motor circuits for a short to voltage. Did you find and correct the condition? If yes, go to step  28. If no, go to next step.
  24. Test for poor connections at the TAC module harness connector. Did you find and correct the condition? If yes, go to step  28. If no, go to step  26.
  25. Test for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step  28. If no, go to step  27.
  26. Replace the TAC module. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  28.
  27. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  28. 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.
  29. 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.
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.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

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.