Engine Coolant Temperature Indicator Malfunction

Engine Coolant Temperature Indicator Malfunction

Diagnostic Instructions

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

Circuit/System Description

The instrument panel cluster (IPC) illuminates the engine coolant temperature indicator when the engine control module (ECM) determines that the coolant temperature is more than 128°C (262°F). The IPC receives a serial data message from the steering column module requesting the illumination of the engine coolant temperature indicator. The engine coolant temperature indicator turns ON and OFF during the bulb test to verify the indicator is working properly at the start of each ignition cycle.


Reference Information
Schematic Reference

* Instrument Cluster Schematics (Instrument Cluster Schematics)
* Engine Cooling Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Instrument Cluster Description and Operation (Description and Operation)
* Cooling Fan Description and Operation (Description and Operation)
* Indicator/Warning Message Description and Operation (Indicator/Warning Message Description and Operation)

Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

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

Circuit/System Verification

1. Ignition ON, scan tool installed, perform the Coolant Temperature Telltale Test. Verify that the engine coolant temperature indicator turns ON and OFF when commanded.

• If the engine coolant temperature indicator does not turn ON and OFF when commanded, replace the IPC.

2. Ignition ON, verify that the scan tool Engine Coolant Temperature parameter is less than 248°F (120°C).

• If greater than the specified value, refer to Engine Overheating (Engine Overheating).

Repair Instructions

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

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