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Home >> Oldsmobile >> 2002 >> Bravada AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 4.2L >> Diagnostic Tests >> DTC P1120: TP Sensor Circuit >> 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. Turn ON the ignition, with the engine OFF. With a scan tool, observe the TP sensor voltage with the accelerator pedal in the rest position. Does the scan tool indicate voltage less than 0.27 V or greater than 4.67 V? If yes, go to step  5 . If no, go to next step.
  3. Is DTC P1221 also set? If yes, see DTC P1221:  . If no, go to next step.
  4. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  5. Turn OFF the ignition. Disconnect the throttle body harness connector. Turn ON the ignition, with the engine OFF. With a scan tool, observe the TP sensor 1 voltage parameter. Does the scan tool indicate voltage at 0 V? If yes, go to next step. If no, go to step  11 .
  6. Connect a fused jumper wire between the TP sensor 5-volt reference circuit and the TP sensor signal circuit at the throttle body harness connector. With a scan tool, observe the TP sensor 1 voltage parameter. Does the scan tool indicate the TP sensor 1 voltage at 5 V? If yes, go to next step. If no, go to step  8 .
  7. With a test lamp connected to battery voltage, probe the TP sensor low reference circuit. Does the test lamp illuminate? If yes, go to step  17 . If no, go to step  13 .
  8. With a Digital Multimeter (DMM), measure the voltage of the TP sensor 1 5-volt reference circuit. Does the DMM indicate voltage at 5 V? If yes, go to step  10 . If no, go to next step.
  9. Does the DMM indicate voltage less than 5 V on the TP sensor 1 5-volt reference circuit? If yes, go to step  14 . If no, go to step  16 .
  10. Test the TP sensor 1 signal circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  21 . If no, go to step  12 .
  11. Test the TP sensor 1 signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  21 . If no, go to step  19 .
  12. Test the TP sensor 1 signal circuit for a short to ground. Did you find and correct the condition? If yes, go to step  21 . If no, go to step  19 .
  13. Test the TP sensor 1 low reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  21 . If no, go to step  19 .
  14. Test the TP sensor 1 5-volt reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  21 . If no, go to next step.
  15. Test the TP sensor 1 5-volt reference circuit for a short to ground. Repair as necessary. After repairs, go to step  21 . If no, go to step  19 .
  16. Test the TP sensor 1 5-volt reference circuit for a short to voltage. Repair as necessary. After repairs, go to step  21 .
  17. Inspect for poor connections at the throttle body harness connector. Did you find and correct the condition? If yes, go to step  21 . If no, go to next step.
  18. Replace the throttle body assembly. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  21 .
  19. Inspect for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step  21 . If no, go to next step.
  20. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  21. 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 .
  22. 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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