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Home >> Chevrolet >> 2003 >> Tracker 2D Utility, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 2.0L >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor Performance >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, 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. Operate the engine until a normal operating temperature is reached. Turn ignition on, with engine off. Install a scan tool. Observe the Throttle Position (TP) sensor voltage parameter on scan tool. Is TP sensor voltage within 0.5-1.2 volts at idle and 3.4-4.7 volts at WOT? If yes, go to next step. If no, go to step  5.
  4. Perform the scan tool Clear DTC Information function. Operate the vehicle within the Freeze Frame conditions as specified, or until the DTC P0121 diagnostic has run. Is DTC P0121 set? If yes, to next step. If no, see DIAGNOSTIC AIDS .
  5. Turn ignition off. Disconnect TP sensor electrical connector. Connect a DVOM between terminals No. 1 and 3. Is resistance within 4-6k ohms? If yes, go to next step. If no, go to step  8.
  6. Check that throttle plate is closed. Connect a DVOM between terminals No. 1 and 2. Is resistance within 0.5-1.0k ohms? If yes, go to next step. If no, go to step  8.
  7. Leave DVOM connected between terminals No. 1 and 2. Slowly move throttle from closed to open while observing the DVOM. Does resistance value change smoothly from low to high, while staying within 0.5-6.0k ohms? If yes, go to step  9. If no, go to next step.
  8. Replace TP sensor. After replacing sensor, go to step  11.
  9. Inspect the TP sensor electrical circuits for a short to ground, short to voltage, high electrical resistance, or an intermittent or faulty connection. Repair as necessary. Was a repair necessary? If yes, go to step  11. If no, 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. 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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