The PCM compares Engine Coolant Temperature (ECT), Intake Air Temperature (IAT), and Ambient Air Temperature (AAT) under cold start conditions. Following a start to run delay time, the sensor values are compared. If the one sensor value is not within a specified range of the other two sensors, the value is determined to be irrational. Once the general temperature rationality is passed, the PCM determines that the general temperature sensor values are correct. The PCM compares the Engine Oil Temperature (EOT) sensor value to a threshold based on the other temp sensor values. If the difference is greater than a calibrated value, the diagnostic fails.
Removal & Installation
- Before servicing the vehicle, refer to the Precautions section.
- Disconnect the negative battery cable.
- Partially drain the engine coolant.
- Remove the upper radiator hose.
- Remove all alternator mounting bolts.
- Remove the alternator electrical connectors.
- Unclip the Engine Oil Temperature (EOT) sensor electrical connector.
- Remove the EOT sensor.
- Apply thread sealant to sensor threads.
- Install the EOT sensor.
- Tighten the sensor to 20 ft. lbs. (28 Nm).
- Connect the electrical connector to EOT sensor.
- Install all alternator mounting bolts.
- Install the alternator electrical connectors.
- Install upper the radiator hose.
- Refill engine coolant.
- Connect the negative battery cable.
- Turn the ignition off.
- Disconnect the Engine Oil Temperature (EOT) sensor harness connector.
- Turn the ignition on.
- With a scan tool, read the EOT sensor voltage.
- The sensor voltage should be approximately 5.0 volts (plus or minus .1 volt) with the connector disconnected.
- If the reading was not as stated check the EOT signal circuit for high resistance.
- If the reading was approximately 5.0 volts (plus or minus .1 volt). Turn the ignition off.
- Connect a jumper wire between the G24 (Pin 1) EOT signal circuit and the K900 (Pin 2) sensor ground circuit in the Engine Oil Temperature Sensor (EOT) harness connector. Turn the ignition on.
- With a scan tool, read the Engine Oil Temperature Sensor voltage.
- The sensor voltage should be approximately 0.0 volts (plus or minus .1 volt) with the jumper wire in place.
If the reading was not as stated, replace the EOT Sensor.