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Home >> Chevrolet >> 2000 >> Lumina >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 3.1L >> Diagnostic Tests >> DTC P0121: TP Sensor Performance >> Diagnostic Procedure
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Diagnostic Procedure

  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. Turn ignition on. Using scan tool, monitor TP sensor angle reading while slowly opening throttle. If TP sensor value increases steadily and evenly from closed throttle value to wide open throttle (0-100 percent), see DIAGNOSTIC AIDS . If TP sensor value does not increase steadily and evenly from closed throttle value to wide open throttle (0-100 percent), go to next step.
  3. Turn ignition off. Disconnect TP sensor harness connector. See Figure. Turn ignition on. Using scan tool, observe TP voltage parameter. If scan tool reading is about zero volts, go to next step. If scan tool reading is not about zero volts, go to step  5.
  4. Turn ignition off. Connect a 3-amp fused jumper wire between 5-volt reference circuit (Gray wire) at TP sensor harness connector terminal "A" and signal circuit (Dark Blue wire) at TP sensor harness connector terminal "C". If scan tool displays 5 volts, go to step  8. If scan tool does not display 5 volts, go to step  6.
  5. Check for short to voltage in signal circuit (Dark Blue wire) between TP sensor harness connector terminal "C" and PCM harness connector C2 terminal No. 66. PCM is located on right side of engine compartment, in front of strut tower. See Figure. Repair circuit as necessary, then go to step  12. If circuit is okay, go to step  11.
  6. Check for high resistance in 5-volt reference circuit (Gray wire) between TP sensor harness connector terminal "A" and PCM harness connector C2 terminal No. 33. Also, check for poor connection at PCM. Repair circuit or connector as necessary, then go to step  12. If circuit and connector are okay, go to next step.
  7. Check for high resistance in signal circuit (Dark Blue wire) between TP sensor harness connector terminal "C" and PCM harness connector C2 terminal No. 66. Also, check for poor connection at PCM Repair circuit or connector as necessary, then go to step  12. If circuit and connector are okay, go to step  11.
  8. Check for high resistance in sensor ground circuit (Black wire) between TP sensor harness connector terminal "B" and PCM harness connector C1 terminal No. 61. Also, check for poor connection at PCM. Repair circuit or connector as necessary, then go to step  12. If circuit and connector are okay, go to next step.
  9. Inspect TP sensor harness connector for poor connections. Repair connector as necessary, then go to step  12. If connector is okay, go to next step.
  10. Replace TP sensor. After repairs, go to step  12.
  11. Replace PCM. Program replacement PCM using required equipment. See PROGRAMMING . After repairs, go to next step.
  12. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC. If scan tool indicates that this DTC FAILED THIS IGN, go to step  2. If scan tool does not indicate that this DTC FAILED THIS IGN, system is okay.
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