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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 P0123: TP Sensor Circuit High Input >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic II (OBD-II) system check. See SELF-DIAGNOSTICS - INTRODUCTION article. Go to next step.
  2. Turn ignition on, engine off. Using scan tool, read TP sensor value. If reading is more than 4.78 volts, go to step  4 . If reading is 4.78 volts or less, go to next step.
  3. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Read SPECIFIC DTC data. If scan tool displays DTC P0123 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0123 FAILED THIS IGN, go to DIAGNOSTIC AIDS  .
  4. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Monitor TP SENSOR data. If reading is about zero volts, go to next step. If reading is not as specified, go to step  6 .
  5. Connect a test light between TP sensor harness connector ground circuit and positive battery terminal. If test light does not illuminate, go to step  10 . If test light illuminates, go to step  7 .
  6. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Check TP sensor signal circuit for a short to voltage. If short to voltage exists, repair as necessary. Retest system. If short to voltage does not exist, go to step  12 .
  7. Turn ignition on. While monitoring scan tool TP SENSOR display, disconnect each component (one at a time) that shares common 5-volt reference circuit. If display changes, replace component that causes change. Retest system. If display does not change, go to next step.
  8. Turn ignition off. Disconnect PCM connectors. Turn ignition on, engine off. Check 5-volt reference circuit between PCM and TP sensor harness connectors for short to voltage. If short is found, repair as necessary. Retest system. If no short is found, go to next step.
  9. Check for faulty connection at TP sensor. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to step  11 .
  10. Turn ignition off. Disconnect PCM connectors. Check for faulty TP sensor ground circuit between PCM and TP sensor harness connectors. Repair as necessary. Retest system. If circuit is okay, 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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