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Home >> Chevrolet >> 2001 >> Camaro Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P1221: Throttle Position Sensor 1 & 2 Disagree >> Diagnostic Procedures

Diagnostic Procedures

  1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM CHECKS. After performing powertrain diagnostic system check, go to next step.
    NOTE: Check for additional DTCs. If DTC P1120, P1220 or P1518 are set, diagnose those DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Turn ignition on. Using scan tool, monitor AGREE/DISAGREE parameters for TP sensor 1 and 2. If scan tool displays AGREE, go to next step. If scan tool displays DISAGREE, go to step  4.
  3. Using scan tool, monitor DTC information for this DTC. Move wiring harness and related connectors. If DTC sets this ignition, go to step  10. If DTC does not set this ignition, go to DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect TAC assembly throttle body connector. See Figure. Turn ignition on. Using DVOM, measure voltage between ground and TAC assembly connector terminals "C" (Gray wire) and "F" (Gray/Black wire). If voltage is 3.9-4.6 volts at each terminal, go to next step. If voltage is not 3.9-4.6 volts at each terminal, go to step  11.
  5. Using DVOM, measure voltage between ground and TAC assembly connector terminals "B" (Purple wire) and "G" (Dark Green wire). If voltage is 3.9-4.6 volts at each terminal, go to next step. If voltage is not 3.9-4.6 volts at each terminal, go to step  12.
  6. Turn ignition off. Using DVOM, check for continuity between TAC assembly connector terminals "C" and "F" (component side). If continuity is indicated, go to step  13. If continuity is not indicated, go to next step.
  7. Using DVOM, check for continuity between TAC assembly connector terminals "B" and "G" (component side). If continuity is indicated, go to step  13. If continuity is not indicated, go to next step.
  8. Locate and disconnect TAC module connector. TAC module is mounted to accelerator pedal assembly. Using DVOM, check for continuity between TAC assembly connector terminals "C" (Gray wire) and "F" (Gray/Black wire). If continuity is indicated, go to step  15. If continuity is not indicated, go to next step.
  9. Using DVOM, check for continuity between ground and TAC assembly connector terminals "B" (Purple wire) and "G" (Dark Green wire). If continuity is indicated, go to step  16. If continuity is not indicated, go to step  14.
  10. Repair harness or connections as necessary. After repairs, go to step  17.
  11. Check for short to voltage in Gray or Gray/Black wire. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  14.
  12. Check for short to voltage in Purple or Dark Green wire. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  14.
  13. Replace TAC assembly. TAC contains both TP sensors. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After repairs, go to step  17.
  14. Replace TAC module. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After repairs, go to step  17.
  15. Repair short between Gray and Gray/Black wire. After repairs, go to step  17.
  16. Repair short between Purple and Dark Green wire. After repairs, go to next step.
  17. Using scan tool, clear DTCs. Turn ignition off for at least 30 seconds. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions for setting 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, go to step  2.
  18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no undiagnosed DTCs are displayed, system is okay.
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