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Home >> Oldsmobile >> 2003 >> Bravada AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 4.2L >> Diagnostic Tests >> DTC P1516: Commanded Vs. Actual Throttle Position Performance (TAC Module) >> Diagnostic Procedures

Diagnostic Procedures

  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. Are DTCs P1120, P1220, P1221, P1271, P1275, and P1280 also set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
    3. NOTE: The throttle angle and pedal angle may not correspond during this procedure.
  3. Turn ignition on, with engine off. Observe the TP sensor 1 and 2 angle parameters. Apply and release the accelerator pedal several times. Does the TP sensor 1 and 2 angle parameters increase as the pedal is applied and decrease as the pedal is released? If yes, go to next step. If no, go to step  5.
  4. Observe the Freeze Frame/Failure Records for this DTC. Start the engine. Operate the vehicle within the Conditions For Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  5. Turn ignition on, with engine off. Probe both sides of the ETC fuse with a test light. Does the test light illuminate on both sides of the fuse? If yes, go to next step. If no, go to step  16.
  6. Turn ignition off. Probe both sides of the ETC/TAC fuse with a test light. Does the test light illuminate on both sides of the fuse? If yes, go to step  22. If no, go to next step.
  7. Turn ignition off. Disconnect the PCM connector containing the ETC/TAC ignition 1 voltage circuit. Turn ON the ignition. Probe the ETC/TAC ignition 1 voltage circuit with a test light. Does the test light illuminate? If yes, go to next step. If no, go to step  23.
  8. Turn ignition off. Inspect the throttle body for throttle valve that is NOT in the rest position, throttle valve that is binding open or closed, or throttle valve that is free to move open or closed WITHOUT spring pressure. Did you find any of these conditions with the throttle body? If yes, go to step  24. If no, go to next step.
    9. NOTE: The test light may momentarily flash when testing these circuits. This is considered normal.
  9. Disconnect the throttle body harness connector. Turn ignition on, with engine off. Probe the TAC motor control 1 and 2 circuits with the test light connected to ground. Did the test light illuminate and remain illuminated on either circuit? If yes, go to step  13. If no, go to next step.
    10. NOTE: The test light may momentarily flash when testing these circuits. This is considered normal.
  10. Probe the TAC motor control 1 and 2 circuits with the test light connected to battery positive. Did the test light illuminate and remain illuminated on either circuit? If yes, go to step  14. If no, go to next step.
  11. Turn ignition off. Connect the test light between the TAC motor control 1 and battery ground. Observe the test light as you turn ON the ignition. Does the test light flash ON and then turn OFF? If yes, go to next step. If no, go to step  15.
  12. Turn ignition off. Connect a test light between the TAC motor control 2 circuit and battery ground. Observe the test light as you turn ON the ignition. Does the test light flash ON and then OFF? If yes, go to step  18. If no, go to step  15.
  13. Turn ignition off. Disconnect the PCM connector that contains the TAC motor control circuits. Turn ignition on, with engine off. Probe the TAC motor control 1 and 2 circuits with the test light connected to ground. Does the test light illuminate? If yes, go to step  20. If no, go to step  19.
  14. Turn ignition off. Disconnect the PCM connector that contains the TAC motor control circuits. Probe the TAC motor control 1 and 2 circuits with the test light connected to battery positive. Does the test light illuminate? If yes, go to step  21. If no, go to step  19.
  15. Turn ignition off. Disconnect the PCM connector that contains the TAC motor controls circuits. Test TAC motor control 1 and 2 circuits for an open or high resistance. Repair circuit as necessary. Did you find and correct the condition? If yes, go to step  26. If no, go to step  19.
  16. Test the ETC/TAC ignition 1 voltage circuit for a short to ground. Did you find and correct the condition? If yes, go to step  26. If no, go to next step.
  17. Test the motor control 1 circuit for a short to ground. Did you find and correct the condition? If yes, go to step  26. If no, go to step  24.
  18. Test for a poor connection or terminal tension at the throttle body connector. Did you find and correct the condition? If yes, go to step  26. If no, go to step  24.
  19. Test for a poor connection or terminal tension at the PCM. Did you find and correct the condition? If yes, go to step  26. If no, go to step  24.
  20. Repair short to voltage on the circuit where the test light remained illuminated. After repairs, go to step  26.
  21. Repair short to ground on the circuit where the test light remained illuminated. After repairs, go to step  26.
  22. Repair short to voltage on the ETC ignition 1 voltage circuit. After repairs, go to step  26.
  23. Repair open or high resistance in the ETC ignition 1 voltage circuit. After repairs, go to step  26.
  24. Replace throttle body assembly. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. After repairs, go to step  26.
  25. Replace PCM. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  26. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  27. Observe the stored information, Capture Info with scan tool. Does 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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