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Home >> Chevrolet >> 2001 >> Metro >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 1.3L >> Diagnostic Tests >> DTC P0121: TP Sensor System Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. Ensure engine is at normal operating temperature. Turn ignition on, with engine off. Using scan tool, monitor TP sensor voltage parameter. If TP sensor value is 0.2-1.0 volt with throttle at idle position, and 3.0-4.8 volts at WOT, see DIAGNOSTIC AIDS . If voltage is not as specified, go to next step.
  3. Disconnect TP sensor harness connector. Using DVOM connected to ground, backprobe PCM harness connector C2 terminal No. 6 (Green/White wire). See Figure. If voltage reading is 4-5 volts, go to next step. If voltage reading is not 4-5 volts, go to step  5.
  4. Using DVOM, check voltage between ground and TP sensor harness connector terminal No. 3 (Light Green wire). See Figure. If voltage reading is 4-5 volts, go to step  7. If voltage reading is not 4-5 volts, go to step  6.
  5. Turn ignition off. Check for high resistance, short to voltage or short to ground in Light Green/White wire between TP sensor harness connector terminal No. 3 and PCM harness connector C2 terminal No. 6. Check for poor connection in Light Green/Black wire between TP sensor harness connector terminal No. 1 and PCM harness connector C2 terminal No. 9. Repair as necessary. After repairs, go to step  9. If circuits are okay, go to step  8.
  6. Turn ignition off. Check for open in Light Green/White wire between TP sensor harness connector terminal No. 3 and PCM harness connector C2 terminal No. 6. Repair as necessary. After repairs, go to step  9. If circuit is okay, go to step  8.
  7. Turn ignition off. Replace TP sensor. After replacing sensor, go to step  9.
  8. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  9. Turn ignition on, with engine off. Using scan tool, clear DTC information. Operate vehicle within FREEZE FRAME/FAILURE RECORDS data conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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