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Home >> Pontiac >> 2003 >> Aztek AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0121: TP Sensor Performance >> Diagnostic Procedures
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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. Inspect for any vacuum hoses that are disconnected, damaged or incorrectly routed MAP sensor vacuum hose, disconnected, damaged or restrictions in the MAP sensor vacuum source, or check for any intake manifold vacuum leaks. Did you find and correct the condition? If yes, go to step  24. If no, go to next step.
    3. NOTE: The vehicle used for the comparison is not limited to the same type of vehicle as is being serviced. A vehicle known to provide an accurate reading is acceptable.
  3. Do you have access to another vehicle in which the MAP sensor pressure can be observed with a scan tool? If yes, go to next step. If no, go to step  5.
  4. Turn ignition on, with engine off. Observe the MAP sensor pressure with a scan tool. Observe the MAP sensor pressure in the known-good vehicle with a scan tool. Compare the values. Is the difference between the values less than 3 kPa? If yes, go to step  6. If no, diagnose MAP sensor. See DTC P1106: MAP SYSTEM PERFORMANCE  or DTC P1107: MAP SENSOR CIRCUIT LOW VOLTAGE  .
    5. NOTE: The Altitude vs Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. Weather conditions consisting of very low or very high pressure and/or very low or very high temperature may cause a reading to be slightly out of range.
  5. Turn ignition on, with engine off. Observe the MAP sensor pressure with a scan tool. The MAP sensor pressure should be within the range specified for your altitude. Refer to SENSOR OPERATING RANGE CHARTS - TRUCKS article. Does the MAP sensor indicate the correct barometric pressure? If yes, go to next step. If no, diagnose MAP sensor. See DTC P1106: MAP SYSTEM PERFORMANCE  or DTC P1107: MAP SENSOR CIRCUIT LOW VOLTAGE  .
  6. Observe the MAP sensor pressure with a scan tool. Start engine. Does the MAP sensor pressure change? If yes, go to next step. If no, diagnose MAP sensor. See DTC P1106: MAP SYSTEM PERFORMANCE  or DTC P1107: MAP SENSOR CIRCUIT LOW VOLTAGE  .
  7. Turn ignition off. Turn ignition on, with engine off. Observe the TP sensor parameter with the scan tool. Is the voltage less than 0.90 volt with throttle in the closed position? If yes, go to next step. If no, go to step  9.
  8. Observe the TP sensor parameter with the scan tool. Depress the accelerator pedal slowly until the throttle is in the wide-open position. Release accelerator pedal slowly until the throttle is returned to the closed position. Repeat this procedure several times. Does the TP sensor parameter increase steadily to more than 98 percent, and then decrease steadily returning to less than one percent? If yes, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article. If no, go to step  10.
  9. Inspect the throttle body for binding or damaged throttle blade, or for binding or damaged throttle cable. Did you find and correct the condition? If yes, go to step  24. If no, go to next step.
  10. Disconnect the TP sensor electrical connector. Observe the TP sensor parameter with the scan tool. Is the voltage less than 0.1 volt? If yes, go to next step. If no, go to step  15.
  11. Measure the voltage from the 5-volt reference circuit of the TP sensor to a good ground with a DVOM. Is the voltage more than 5.2 volts? If yes, go to step  16. If no, go to next step.
  12. Probe the 5-volt reference circuit of the TP sensor with a test light connected to a good ground. Is the test light OFF? If yes, go to step  17. If no, go to next step.
  13. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the TP sensor and signal circuit of the TP sensor. Observe the TP sensor parameter with scan tool. Is voltage more than 4.9 volts? If yes, go to next step. If no, go to step  18.
  14. Turn ignition off. Remove the jumper wire. Connect a jumper wire between each of the terminals in the TP sensor harness connector and the corresponding terminal at the TP sensor. Turn ignition on, with engine off. Measure the voltage from the low reference circuit of the TP sensor at the jumper wire terminal to a good ground with a DVOM. Is voltage more than 0.2 volt? If yes, go to step  19. If no, go to step  20.
    15. NOTE: Disconnecting the PCM may eliminate the short during testing.
  15. Test the TP sensor signal circuit between the PCM and the TP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step  24. If no, go to step  23.
    16. NOTE: Disconnecting the PCM may eliminate the short during testing.
  16. Test all of the branches of the 5-volt reference circuit that are shared with the TP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step  24. If no, go to step  23.
  17. Test the 5-volt reference circuit between the PCM and the TP sensor for an open or for a high resistance. Did you find and correct the condition? If yes, go to step  24. If no, go to step  21.
  18. Test the TP sensor signal circuit between the PCM and the TP sensor for a short to ground, open, or high resistance. Did you find and correct the condition? If yes, go to step  24. If no, go to step  21.
  19. Test the low reference circuit between the PCM and the TP sensor for an open or for a high resistance. Did you find and correct the condition? If yes, go to step  24. If no, go to step  21.
  20. Test for an intermittent and for a poor connection at the TP sensor. Did you find and correct the condition? If yes, go to step  24. If no, go to step  22.
  21. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  24. If no, go to step  23.
  22. Replace TP sensor. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  24.
  23. Replace PCM. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  24. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start 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 step  2. If no, go to next step.
  25. 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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