LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Isuzu >> 2000 >> Rodeo S, 2.2 D >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.2L >> Diagnostic Trouble Code Identification >> DTC P0121: TP Sensor Circuit Range/Performance >> Diagnostic Procedures
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedures

  1. Perform On-Board Diagnostic II (OBD-II) system check. See SELF-DIAGNOSTICS - INTRODUCTION article. Go to next step.
  2. With ignition on and engine off, review and record FAILURE RECORDS data on scan tool, then clear DTCs. Operate vehicle within FAILURE RECORDS conditions specified. Monitor specified DTC information. If scan tool indicates DTC P0121 RAN AND PASSED, go to DIAGNOSTIC AIDS . If scan tool does not indicate DTC P0121 RAN AND PASSED, go to step  4.
  3. Turn ignition on. While monitoring TP value on scan tool display, move throttle in a smooth even forward motion from closed position to WOT. If value displayed on scan tool changes smoothly from 0 percent (0.25 volt) to 100 percent (4.75 volts), go to next step. If TP value change is not smooth or does not change, go to step  11.
  4. Turn ignition off. Disconnect TP sensor. Start vehicle and monitor TP value on scan tool. If TP value holds steady within 0-0.25 volt, go to step  6. If TP value does not remain within 0-0.25 volt, go to next step.
  5. Turn ignition off. Disconnect all PCM harness connectors. Check for short to voltage between TP sensor harness connector Blue wire (sensor input) and PCM White 32-pin harness connector terminal E8. Repair as necessary. Retest system. If no problem was found, go to step  12.
  6. Check for open circuit or short to ground between TP sensor harness connector Blue wire (sensor input) and PCM White 32-pin harness connector terminal E8. Repair as necessary. Retest system. If no problem was found, go to step next step.
  7. Check for faulty circuit on 5-volt reference circuit between TP sensor and PCM Red 32-pin harness connector terminal A1 (Red wire). Repair as necessary. If no problem was found, go to next step.
  8. Turn ignition off. Using a fused jumper wire, connect TP sensor harness connector Blue wire (input circuit) and Red wire (5-volt reference) together. While monitoring TP value on scan tool, turn ignition on. If TP value indicates about 5 volts and 100 percent, go to next step. If TP value is not as specified, go to step  12.
  9. Tector terminal D8 (Green wire). Repair as necessary. Retest system. If no problem was found, go to next step.
  10. Turn ignition off. Connect all PCM connectors. Using a DVOM, connect positive lead to TP sensor harness connector Red wire (5-volt reference), and negative lead to TP sensor Green wire (ground circuit). Turn ignition on. If reading is about 5 volts, go to next step. If reading is not about 5 volts, go to step  12.
  11. Replace TP sensor. Retest system.
  12. Replace and reprogram PCM using required equipment. See PROGRAMMING . Retest system.
scientia non olet · About LEMON Manuals