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Home >> Isuzu >> 1999 >> Rodeo LS, 2.2 D >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - Tests (2.2L) >> Diagnostic Trouble Code Identification >> DTC P0121: TP Sensor Circuit Range/Performance >> Diagnostic Procedures

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 the DTCs. Operate vehicle within FAILURE RECORDS conditions specified. Monitor SPECIFIC DTC information. If scan tool indicates DTC P0121 RAN AND PASSED, go to next step. 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 in TP sensor input circuit. Repair as necessary. Retest system. If short to voltage is not present, go to step  12 .
  6. Turn ignition off. Disconnect all PCM harness connectors. Check TP sensor input circuit between TP sensor and PCM connectors for an open or short to voltage condition. Repair as necessary. Retest system. If an open or short is not present, go to next step.
  7. Check 5-volt reference circuit between TP sensor and PCM connectors. Turn ignition on. If an open or shorted condition exists, repair as necessary. If an open or shorted condition does not exist, go to next step.
  8. Turn ignition off. Using a fused jumper wire, connect TP sensor input circuit and 5-volt reference terminals of TP sensor connector. 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. Turn ignition off. Disconnect all PCM harness connectors. Check TP sensor ground circuit for an open or shorted condition. If such a condition is indicated, repair as necessary. Retest system. If such condition is not present, go to next step.
  10. Turn ignition off. Connect all PCM connectors. Using a DVOM, connect positive lead to 5-volt reference circuit terminal, and negative lead to TP sensor ground circuit terminal of TP sensor connector. 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 PCM. Program replacement PCM using required equipment. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. Retest system.
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