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Home >> Chevrolet >> 2001 >> Tracker 2D Utility, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Check if DTC P0122 or P0123 is set. If DTC P0122 or P0123 is also set, diagnose affected DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If DTC P0122 or P0123 is not set, go to next step.
  3. Warm engine to normal operating temperature. Turn ignition on, with engine off. Using scan tool, observe TP sensor parameter on scan tool. If scan tool displays 0.2-1.0 volts with throttle at idle position and 3.4-4.7 volts with throttle at WOT, go to next step. If scan tool display is not 0.2-1.0 volts with throttle at idle position and 3.4-4.7 volts with throttle at WOT, go to step  5 .
  4. Using scan tool, clear DTCs. Operate vehicle within FREEZE FRAME conditions. Retrieve DTCs. If this DTC resets, go to next step. If this DTC does not reset, see DIAGNOSTIC AIDS  .
  5. Turn ignition off. Disconnect TP sensor harness connector. Using DVOM, check resistance between TP sensor terminals No. 1 (Gray/Yellow wire) and No. 3 (Gray/Red wire) on 2.0L or terminals No. 1 (Gray/Red wire) and No. 3 (Gray/Yellow wire) on 2.5L. See Figure . If resistance is 4000-6000 ohms, go to next step. If resistance is not 4000-6000 ohms, go to step  8 .
  6. Ensure throttle plate is closed (at idle). Check resistance between TP sensor terminals No. 1 (Gray/Yellow wire) and No. 2 (Red/Green wire). If resistance is 500-1000 ohms, go to next step. If resistance is not 500-1000 ohms, go to step  8 .
  7. Connect DVOM between TP sensor terminals No. 1 (Gray/Yellow wire) and No. 2 (Red/Green wire) on 2.0L or terminals No. 2 (Red/Green wire) and No. 3 (Gray/Yellow wire) on 2.5L. Slowly move throttle from closed to open position while observing DVOM. If resistance changes smoothly from low to high while remaining within 500-6000 ohms, go to step  9 . If resistance does not change smoothly from low to high while remaining within 500-6000 ohms, go to next step.
  8. Replace TP sensor. After replacing sensor, go to step  11 .
  9. Check for high resistance, short to ground or short to voltage in Red/Green wire between TP sensor and PCM. Check for high resistance in Gray/Yellow wire between TP sensor and PCM. Check for poor connection at PCM. Repair as necessary. After repairs, go to step  11 . If circuits and connection are okay, go to next step.
  10. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  11. Turn ignition off. Remove DOME fuse for 30 seconds (fuse is located in passenger compartment fuse block). Reinstall DOME fuse. Reset radio clock time. Start engine. Operate vehicle within the conditions for running DTC or until DTC P0121 diagnostic test has run. See CODE ENABLE CRITERIA  . If DTC runs and passes, go to next step. If DTC resets, go to step  2 .
  12. Using scan tool, observe the stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTCs are displayed, system is okay.
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