Engine Oil Temperature Indicator Always On

Engine Oil Temperature Indicator Always On

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

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) with the engine oil temperature sensor via a discreet signal circuit and low reference circuit. The ECM applies 5 V 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 to +165°C (-40 to +329°F).

Reference Information
Schematic Reference

Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Instrument Cluster Description and Operation (Instrument Cluster)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

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

• If greater than the specified range, 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 greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.

4. Ignition ON, install a 3 A 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 less than the specified range, 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.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for the ECM replacement, setup, and programming