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Home >> Mitsubishi >> 2002 >> Montero XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Test Procedure

Test Procedure

  1. Turn ignition on. Using scan tool, check data list item No. 21 (engine coolant temperature sensor). Turn ignition on. The engine coolant temperature and temperature indicated on the scan tool should approximately match. If the engine coolant temperature sensor is operating properly, problem is intermittent. See INTERMITTENT DIAGNOSTIC TROUBLE CODES . If readings do not match, go to next step.
  2. Turn ignition on. While backprobing Yellow/Green wire at ECT sensor, measure voltage between ground ECT sensor terminal No. 1. See Figure. Refer to ECT SENSOR VOLTAGES . If voltage is as specified, go to next step. If voltage is not as specified, go to step  5.
  3. Turn ignition off. Disconnect ECT sensor connector. See Figure. Check ECT sensor connector for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. Go to step  14. If problem does not exist, go to next step.
  4. Turn ignition on. Using scan tool, check data list item No. 21 (engine coolant temperature sensor). Turn ignition on. The engine coolant temperature and temperature indicated on the scan tool should approximately match. If the engine coolant temperature sensor is operating properly, problem is intermittent. See INTERMITTENT DIAGNOSTIC TROUBLE CODES . If readings do not match, replace PCM. Go to step  14.
  5. Turn ignition off. Disconnect ECT sensor connector. Check ECT sensor connector for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. Go to step  14. If problem does not exist, go to next step.
  6. Turn ignition on. Measure voltage between ground and ECT sensor connector terminal No. 1 (Yellow/Green wire). Voltage should be 4.8-4.9 volts. If voltage is as specified, go to step  8. If voltage is not as specified, go to next step.
  7. Check PCM connector D-108 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. Go to step  14. If problem does not exist, replace PCM. Go to step  14.
  8. Check for continuity between ground and ECT sensor connector terminal No. 2 (Black wire). If continuity exists, go to step  11. If continuity does not exist, go to next step.
  9. Check PCM connector D-108 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. Go to step  14. If problem does not exist, go to next step.
  10. Check continuity between ECT sensor connector terminal No. 2 (Black wire) and PCM connector D-108 terminal No. 57. If continuity exists, replace PCM. Go to step  14. If continuity does not exist, repair Black wire between ECT sensor connector terminal No. 2 and PCM connector D-108 terminal No. 57. Then go to step  14.
  11. Remove ECT sensor. Immerse sensor portion of ECT sensor in hot water and check resistance between ECT sensor connector terminals. Compare resistance with expected value. See ECT SENSOR RESISTANCES . If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor. Go to step  14.
    NOTE: To install ECT sensor, apply thread sealer to ECT sensor threads and tighten ECT sensor to 15-29 ft. lbs. (19-39 N.m).
  12. Check PCM connector D-108 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. Go to step  14. If problem does not exist, go to next step.
  13. With PCM D-108 connector and ECT connector disconnected, check Yellow/Green wire for continuity between ECT sensor connector terminal No. 1 and PCM connector D-108 terminal No. 44. If there is no continuity, repair open in Yellow/Green wire. Go to next step. If problem does not exist, replace PCM. Go to next step.
  14. Test drive vehicle following OBD-II drive cycle Other Monitor pattern. See OTHER MONITOR  under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. If DTC P0125 is output, go to step  1 and retry diagnostic procedure. If DTC P0125 is not output, inspection is complete.
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