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Home >> Pontiac >> 2000 >> Firebird Base, 2D Convertible, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Engine Control System Self-Diagnostics - 5.7L) >> Diagnostic Tests >> DTC P1220: Throttle Position (TP) Sensor No. 2 Circuit ("Y" Body) >> Diagnostic Procedures
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Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . After performing OBD system check, go to next step.
  2. If DTC P1515, P1516 or P1518 is also present, diagnose affected DTC first. If DTC P1515, P1516 or P1518 is not present, go to next step.
    NOTE: Disconnecting throttle actuator motor will cause additional DTCs to set.
  3. Remove duct from throttle body assembly. Disconnect throttle actuator motor connector. Manually close throttle blade while monitoring scan tool TP SENSOR NO. 2 voltage display. If voltage reading is 4.3-4.8 volts, go to next step. If voltage reading is not 4.3-4.8 volts, go to step  7.
  4. Manually rotate throttle blade to wide open throttle. If voltage reading is.13-1.0 volt, go to next step. If voltage reading is not.13-1.0 volt, go to step  7.
  5. Reconnect throttle actuator motor connector. Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool, select DTC function, then enter this DTC. Monitor scan tool while moving wiring harness and related connectors. If scan tool indicates this test failed this ignition, go to step  25. If scan tool does not indicate that this test failed this ignition, go to next step.
  6. While monitoring scan tool, fully open and close throttle. If scan tool indicates this test failed this ignition, go to step  35. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS .
  7. Using scan tool, monitor TP sensor No. 2 voltage. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step  11.
  8. Disconnect TP sensor No. 2 harness connector. If scan tool indicates zero volts, go to next step. If scan tool does not indicate zero volts, go to step  12.
  9. Turn ignition off. Using DVOM, check resistance between battery ground and TP sensor No. 2 ground circuit in TP sensor harness connector. If resistance is 0-5 ohms, go to next step. If resistance is not 0-5 ohms, go to step  33.
  10. Turn ignition off. Disconnect Accelerator Pedal Position (APP) sensor harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between TP sensor No. 2 5-volt reference circuit and battery ground. If voltage reading is about 5 volts, go to step  13. If voltage reading is not about 5 volts, go to step  17.
  11. Disconnect TP sensor harness connector. Using DVOM, check voltage between TP sensor No. 2 signal circuit and battery voltage. If voltage reading is 5 volts, go to step  19. If voltage reading is not 5 volts, go to step  14.
  12. Turn ignition off. Leave TP sensor disconnected. Disconnect Throttle Actuator Control (TAC) module connector containing TP sensor circuits. Turn ignition on, with engine off. Check voltage between battery ground TP sensor No. 2 signal circuit at sensor harness connector. If any voltage is present, go to step  30. If no voltage is present, go to step  16.
  13. Turn ignition off. Disconnect TAC module harness connector. Turn ignition on, with engine off. Check voltage between battery ground and APP sensor No. 2 signal circuit at TAC module harness connector. If any voltage is present, go to step  24. If no voltage is present, go to step  22.
  14. Turn ignition off. Leave TP sensor disconnected. Disconnect TAC module connector containing TP sensor circuits. Check continuity of TP sensor No. 2 signal circuit. If continuity exists, go to next step. If continuity does not exist, go to step  31.
  15. Check continuity between battery ground and TP sensor No. 2 signal circuit. If continuity exists, go to step  32. If continuity does not exist, go to next step.
  16. Check continuity of TP sensor No. 2 signal circuit and all other circuits in both TAC module connectors. If continuity exists, go to step  34. If continuity does not exist, go to step  37.
  17. Turn ignition off. Leave TP and APP sensors disconnected. Disconnect TAC module connector containing the TP sensor circuits. Turn ignition on, with engine off. Check voltage from TP sensor No. 2 5-volt reference circuit in TP sensor harness connector to battery ground. If any voltage is present, go to step  26. If no voltage is present, go to next step.
  18. Turn ignition on. Disconnect the other TAC module connector. Turn ignition on, with engine off. Check voltage from APP sensor No. 2 5-volt reference circuit at TAC module harness connector to battery ground. If any voltage is present, go to step  27. If no voltage is present, go to step  22.
  19. Turn ignition off. Disconnect Throttle Actuator Control (TAC) module connector containing TP sensor circuits. Check resistance of TP sensor No. 2 5-volt reference circuit. If resistance is 0-20 ohms, go to next step. If resistance is not 0-20 ohms, go to step  28.
  20. Check continuity between TP sensor No. 2 5-volt reference circuit and battery ground. If continuity exists, go to step  29. If continuity does not exists, go to next step.
  21. Turn ignition off. Disconnect the other TAC module connector. Check resistance between APP sensor No. 2 5-volt reference circuit and battery ground. If resistance is 0-2 ohms, go to step  29. If resistance is not 0-2 ohms, go to next step.
  22. Check continuity between TP sensor No. 2 5-volt reference circuit and all other circuits in both TAC module connectors. If continuity exists, go to step  34. If continuity does not exist, go to next step.
  23. Check continuity between APP sensor No. 2 5-volt reference circuit and all other circuits in both TAC module connectors. If continuity exists, go to step  34. If continuity does not exist, go to step  35.
  24. Repair short to voltage in APP signal circuit. After repairs, go to step  39.
  25. Repair harness/connections as necessary. After repairs, go to step  39.
  26. Repair short to voltage in TP sensor No. 2 5-volt reference circuit. After repairs, go to step  39.
  27. Repair short to voltage in APP sensor 5-volt reference circuit. After repairs, go to step  39.
  28. Repair open or high resistance in 5-volt reference circuit. After repairs, go to step  39.
  29. Repair short to ground in 5-volt reference circuit. After repairs, go to step  39.
  30. Repair signal circuit shorted to voltage. After repairs, go to step  39.
  31. Replace open or high resistance in signal circuit. After repairs, go to step  39.
  32. Repair short to ground in signal circuit. After repairs, go to step  39.
  33. Repair open or high resistance in ground circuit. After repairs, go to step  39.
  34. Repair circuits that are shorted together. After repairs, go to step  39.
  35. Check for poor terminal contact or terminal tension at TP sensor harness connector. Repair as necessary. After repairs, go to step  39. If terminal contacts or tension are okay, go to next step.
  36. Replace throttle body assembly. After replacing throttle body, go to step  39.
  37. Check for poor terminal contact or terminal tension at TAC module harness connector. Repair as necessary. After repairs, go to step  39. If terminal contacts or tension are okay, go to next step.
  38. Replace TAC module. After replacing module, go to next step.
  39. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions that set this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step  2.
  40. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.
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