- Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Coolant Temperature sensor(s) and the Powertrain Control Module (PCM).
- Look for any chafed, pierced, pinched, or partially broken wires.
- Look for broken, bent, pushed out or corroded terminals.
- Turn the ignition on.
- Monitor the scan tool data relative to the sensor(s) and wiggle test the wiring and connectors.
- Look for the data to change or for a DTC to set during the wiggle test.
- Check the engine coolant level and the condition of the engine coolant.
- With the scan tool, read the Engine Coolant Temperature Sensor value for each sensor. If the engine was allowed to cool completely, the value should be approximately equal to the ambient temperature.
- Monitor each sensor value on the scan tool and the actual coolant temperature with a thermometer.
- Using a diagnostic scan tool, check for the presence of any Diagnostic Trouble Codes (DTC-s). Record and address these codes as necessary.
- If no codes are present, review the scan tool environmental data. If possible, try to duplicate the conditions under which the DTC set.
- If applicable, actuate the component with the scan tool.
- Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
- Look for the data to change, the actuation to be interrupted, or for the DTC to reset during the wiggle test.
- Refer to any Technical Service Bulletins (TSBs) that may apply.
- Turn the ignition off.
- Visually inspect the related wire harness. Disconnect all the related harness connectors. Look for any chafed, pierced, pinched, partially broken wires and broken, bent, pushed out, or corroded terminals.
- Perform a voltage drop test on the related circuits between the suspected component and the Powertrain Control Module (PCM).
- Inspect and clean all PCM, engine, and chassis grounds that are related to the most current DTC.
- If numerous trouble codes were set, use a schematic and inspect any common ground or supply circuits.
- For intermittent Misfire DTC-s check for restrictions in the Intake and Exhaust system, proper installation of Sensors, vacuum leaks, and binding components that are run by the accessory drive belt.
- Use the scan tool to perform a System Test if one applies to the component.
A co-pilot, data recorder, and/or lab scope should be used to help diagnose intermittent conditions.
WARNINGBe careful not to touch the connector (resin section) with the tool when removing and installing.
- Drain engine coolant, and then remove the Engine Coolant Temperature (ECT) sensor.
With the temperature-sensing portion of ECT sensor immersed in hot water, check the resistance against the standard value:
5.1-6.5 k/ohms at 32° F (0° C)
- If resistance deviates from the standard value greatly, replace the sensor.
- Apply 3M® AAD part number 8731, or equivalent, to the threaded portion.
- Install the ECT sensor and tighten it to 14 ft. lbs. (19 Nm).