The engine oil temperature sensor is a thermistor that varies in resistance as the engine oil temperature changes. A low engine oil temperature produces a high resistance at the engine oil temperature sensor. A high engine oil temperature produces a low resistance at the engine oil temperature sensor. The engine control module (ECM) monitors the engine oil temperature sensor via a discreet signal circuit and low reference circuit. The ECM applies 5 volts to the engine oil temperature sensor and calculates temperature based on the engine oil temperature sensor voltage. The engine oil temperature range is between -40°C (-40°F) to -165°C (329°F).

Schematic Reference

Connector End View Reference

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition OFF, disconnect the harness connector at the engine oil temperature sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal C and ground.

⇒	If greater than 1 ohm, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Engine Oil Temperature Calculated parameter is less than -10°C (14°F)

⇒	If not, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.

4. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal C. Verify the scan tool Engine Oil Temperature Calculated parameter is greater the 150°C (302°F).

⇒	If not, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the engine oil temperature sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.