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Home >> Jaguar >> 2000 >> XJ8 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Trouble Code Identification >> DTC P0125: Engine Coolant Temperature Sensor Response (For Closed Loop Fuel Control) >> Diagnostic Test Procedure

Diagnostic Test Procedure

NOTE: Before performing this procedure, check the coolant level, coolant condition and operation of the thermostat. Repair as necessary.
NOTE: As a guideline, coolant temperature overnight will drop to approximately -4-104°F (-20-40°C), at which the resistance of the sensor should be 15.04-1.15 k/ohms. See IAT & ECT SENSOR RESISTANCE  table.
  1. Disconnect negative battery cable. Disconnect ECM connectors EM82 and EM83. Disconnect the ECT sensor connector. Measure resistance between ECM harness connector EM82 terminal No. 14 and ECT sensor harness connector terminal No. 2. Is resistance greater than 5 ohms? If yes, repair the high resistance between ECM harness connector EM82 terminal No. 14 and ECT sensor harness connector terminal No. 2. If no, go to next step.
  2. Reconnect negative battery cable. Turn ignition on. Measure the voltage between ECT sensor terminal 2 and ground. Is voltage greater than 3 volts? If yes, repair the short to voltage. If no, go to next step.
  3. Turn ignition off. Measure resistance between ECT sensor harness connector terminal No. 2 and ground. Is resistance less than 10,000 ohms? If yes, repair short to ground. If no, go to next step.
  4. Measure the resistance between the terminals of the ECT sensor. Is resistance within 10 percent of specification? If no, install a new ECT sensor. See IAT & ECT SENSOR RESISTANCE  table. If yes, recheck the DTCs. If DTC resets, possible ECM failure.
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