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Home >> Isuzu >> 2000 >> Trooper S, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 3.2L & 3.5L >> Diagnostic Trouble Code Identification >> DTC P0125: Excessive Time To Closed Loop >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC DIAGNOSTIC PROCEDURES article. Go to next step.
  2. If any Engine Coolant Temperature (ECT) DTCs are set, see appropriate diagnostic test. If no DTCs are set, go to next step.
  3. Allow engine to cool. Ensure coolant level is full. If coolant level is okay, go to next step. If coolant level is low, check cooling system for leaks. Repair as necessary. Retest system.
  4. Start engine and let idle. Using scan tool, select ENG COOL TEMP. If display increases to greater than 70°F (21°C) within 2 minutes, check for an intermittent problem. See DIAGNOSTIC AIDS . If display is not as specified, go to next step.
  5. Check thermostat for proper operation. Replace thermostat if necessary. Retest system. If thermostat is okay, go to next step.
  6. Using a thermometer, check temperature of coolant in radiator. Compare reading with display on scan tool. If readings are fairly close, check for sticking thermostat or incorrect thermostat application. Repair as necessary. If display readings are not close, go to next step.
  7. Turn ignition off. Disconnect PCM harness connectors. Measure resistance between ECT sensor signal circuit and ECT sensor ground circuit at PCM harness connector. Compare resistance reading with coolant temperature. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR RESISTANCE  table under DTC P0117. If readings are as specified, replace and reprogram PCM. See PROGRAMMING . Retest system. If readings are not as specified, go to next step.
  8. Check for high resistance in ECT sensor signal circuit or sensor ground circuit. Check for poor connections at PCM and ECT sensor. Repair as necessary. If ECT sensor circuit is okay, replace ECT sensor. Retest system.
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