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Home >> Isuzu >> 2001 >> Rodeo S, 2.2 D, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.2L >> Diagnostic Tests >> DTC P0121: TP Sensor Circuit Range/Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform OBD-II system check. See ON-BOARD DIAGNOSTIC II (OBD-II) SYSTEM CHECK  . After performing OBD-II system check, 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 next step.
  3. Turn ignition on. While monitoring TP value on scan tool display, move throttle in a smooth even 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 harness connector. Start vehicle and monitor TP value on scan tool. If TP value holds steady at 0-0.25 volt, go to step  6 . If TP value does not remain at 0-0.25 volt, go to next step.
  5. Turn ignition off. Disconnect all PCM harness connectors. Check for short to voltage in Blue wire (sensor input) between PCM harness connector terminal E8 and TP sensor harness connector. See Figure and Fig 1 . Repair as necessary. Retest system. If no problem was found, go to step  12 .
  6. Check for open circuit or short to ground in Blue wire between PCM harness connector terminal E8 and TP sensor harness connector. See Figure and Fig 1 . Repair as necessary and retest system. If no problem was found, go to step next step.
  7. Check for faulty circuit on Red wire between TP sensor harness connector and PCM harness connector terminal A1. 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 and Red wires 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. Turn ignition off. Disconnect all PCM harness connectors. Check for faulty TP sensor ground circuit between TP sensor and PCM harness connector terminal D8 (Green wire). See Figure and Fig 1 . Repair as necessary and retest system. If no problem was found, go to next step.
  10. Turn ignition off. Connect all PCM harness connectors. Using a DVOM, connect positive lead to TP sensor harness connector Red wire, and negative lead to TP sensor Green wire. 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.
Fig 1: Identifying TP Sensor Circuit
G00049067Courtesy of ISUZU MOTOR CO.
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