For a complete wiring diagram Refer to Section 8W.When Monitored:With the ignition on. Battery voltage greater than 10.4 volts.Set Condition:The Engine Coolant Temperature (ECT) sensor circuit voltage at the PCM is greater than 4.98 volts for more than 2.8 seconds. One Trip Fault. Three good trips to turn off the MIL. (ETC lamp will illuminate with the MIL if equipped.)Possible Causes(K2) ECT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE(K2) ECT SIGNAL CIRCUIT OPEN(K900) SENSOR GROUND CIRCUIT OPENECT SENSORPCMAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).1. ECT SENSOR VOLTAGE ABOVE 4.98 VOLTSIgnition on, engine not running.With a scan tool, read the ECT voltage.Is the voltage above 4.98 volts?YesGo To 2 NoRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 2. ECT SENSOR

Turn the ignition off.Disconnect the ECT harness connector.Connect a jumper wire between the (K2) ECT Signal circuit and the (K900) Sensor ground circuit in the ECT harness connector.Ignition on, engine not running.With a scan tool, read ECT voltage.Is the voltage below 1.0 volt with the jumper wire installed?YesReplace the ECT Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoGo To 3Remove the jumper wire before continuing.3. (K2) ECT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Turn the ignition off.Disconnect the C2 PCM harness connector.Ignition on, engine not running.Measure the voltage on the (K2) ECT Signal circuit in the ECT Sensor harness connector.Is the voltage above 0 volts?YesRepair the short to battery voltage in the (K2) ECT Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoGo To 44. (K2) ECT SIGNAL CIRCUIT OPEN

Turn the ignition off.Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.Measure the resistance of the (K2) ECT Signal circuit from the ECT Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 5NoRepair the open in the (K2) ECT Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 5. (K900) SENSOR GROUND CIRCUIT OPEN

Measure the resistance of the (K900) Sensor ground circuit from the ECT Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 6NoRepair the open in the (K900) Sensor ground circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 6. PCM Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.Were there any problems found?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)