LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1999 >> Forward Control 6.5 F, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - DTC P0100-P0134 >> DTC P0121 >> DTC P0121: TP Sensor Performance (2.2L "J" Body) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. Turn ignition on. Using scan tool, establish communication with AFECU. Monitor TP sensor angle data. If TP angle is less than 2 percent, go to next step. If TP angle is not less than 2 percent, go to step  6.
  3. Slowly depress throttle to Wide Open Throttle (WOT). If TP angle is greater than 98 percent, go to next step. If TP angle is not greater than 98 percent, go to step  6.
  4. Release throttle. If TP angle is less than 2 percent, go to next step. If TP angle is not less than 2 percent, go to step  6.
  5. Fault is not present at this time. If any undiagnosed DTCs are present, diagnose affected DTCs. If no undiagnosed DTCs are present, see DIAGNOSTIC AIDS .
  6. Disconnect TP sensor. If TP sensor voltage is greater than 4.9 volts, go to next step. If TP sensor voltage is not greater than 4.9 volts, go to step  10.
  7. Measure voltage between ground and 5-volt reference circuit at TP sensor harness connector. If voltage is 4.8-5.2 volts, go to next step. If voltage is not as specified, go to step  12.
  8. Using a fused jumper wire, jumper TP sensor signal circuit to engine ground. If TP sensor voltage is less than.08 volt, go to next step. If TP sensor voltage is not less than.08 volt, go to step  14.
  9. Using a fused jumper wire, jumper 5-volt reference circuit and signal circuit together at TP sensor harness connector. Connect an additional fused jumper wire sensor ground circuit and 5-volt reference circuit at TP sensor harness connector. If TP sensor voltage is less than.08 volt, go to step  11. If TP sensor voltage is not less than.08 volt, go to step  15.
  10. Check TP sensor signal circuit for short to ground or sensor ground circuit. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to step  18.
  11. Check TP sensor signal circuit for short to voltage or 5-volt reference circuit. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to step  16.
  12. Turn ignition off. Disconnect AFECU harness connectors. Turn ignition on. Measure voltage between ground and 5-volt reference circuit at TP sensor harness connector. If voltage is 4.8-5.2 volts, go to step  18. If voltage is not as specified, go to next step.
  13. Check 5-volt reference circuit for a short to voltage, ground or high circuit resistance. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to step  17.
  14. Check TP sensor signal circuit for an open or high resistance. Check all circuit related connectors and splices for poor terminal contact. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to step  18.
  15. Check TP sensor ground circuit for high resistance or poor terminal contact at PCM. Repair as necessary. After repairs, go to step  19. If circuit is okay, go to step  17.
  16. Replace TP sensor. After repairs, go to step  19.
  17. Replace PCM. Program replacement PCM using required equipment. Perform CKP system variation learn procedure. After repairs, go to step  19.
  18. Replace AFECU. After repairs, go to next step.
  19. Using scan tool, clear DTCs from both control modules. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, and then enter DTC P0118. Operate vehicle within conditions that set DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step  2.
scientia non olet · About LEMON Manuals