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  • P0118 Engine Coolant Temperature Sensor Voltage Too High

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    Mopar1973Man

    DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR VOLTAGE TOO HIGH

    Monitor & Set Conditions

    Engine Coolant Temperature (ECT) sensor voltage is monitored when the ignition is on and battery voltage is greater than 10.4 volts. DTC may be stored when ECT sensor voltage at Engine Control Module (ECM) is greater than 4.98 volts for greater than 2 seconds.

    Possible Causes

    • Intermittent Wiring
    • ECT Signal Circuit Shorted To Voltage
    • ECT Signal Circuit Open
    • Sensor Ground Circuit Open
    • ECT Sensor
    • ECM

    Testing

    1. Turn ignition on with engine off. Using DRBIII(R) scan tool, read ECT sensor voltage. If ECT sensor voltage is greater than 4.6 volts, go to next step. If ECT sensor voltage is 4.6 volts or less, go to step 6.

    2. Turn ignition off. Disconnect ECT sensor harness connector. The ECT sensor is located at the front of the cylinder head, near the thermostat housing. Turn ignition on with engine off. Using scan tool, read ECT sensor voltage. If ECT sensor voltage is 6 volts or less, go to next step. If ECT sensor voltage is greater than 6 volts, repair short to voltage in Tan/Black wire between ECT sensor and ECM.

    3. Turn ignition off. Ensure ECT sensor connector is still disconnected. Connect fused jumper wire between ECT sensor harness connector terminals. Turn ignition on with engine off. Using scan tool, read ECT sensor voltage. If ECT sensor voltage is one volt or greater, go to next step. If ECT sensor voltage is less than one volt, replace the ECT sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

    4. Turn ignition off. Remove jumper wire from ECT sensor harness connector. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50- pin connector. Using DVOM, measure resistance of Tan/Black wire between terminal "B" on ECT sensor connector and terminal No. 14 on ECM connector. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or greater, repair open in Tan/Black wire between ECT sensor and ECM.

    5. Using DVOM, measure the resistance of Black/Light Blue wire between terminal "A" on ECT sensor connector and terminal No. 11 on ECM connector. If resistance is less than 10 ohms, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If resistance is 10 ohms or greater, repair open in Black/Light Blue wire between ECT sensor and ECM.

    6. The conditions that set the DTC are not present at this time. With ignition on engine off, monitor scan tool parameters related to the DTC while wiggling wiring harness. Look for parameter values to change and/or a DTC to set. Review the DRBIII(R) Freeze Frame information. If possible, try to duplicate the conditions under which the DTC was set. Refer to any Technical Service Bulletins (TSB) that may apply. Visually inspect the related wire harness. Look for any chafed, pierced, pinched or partially broken wires. Visually inspect the related wire harness connectors. Look for broken, bent, pushed out or corroded terminals. Was any of the above conditions present? If yes, repair as necessary. If no, the test is complete.



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