Coolant Heater Inoperative

Coolant Heater Inoperative

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.

Circuit/System Description

The coolant heater operates using 110 V AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. The coolant heater also helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. There is an internal thermal switch in the coolant heater cord that prevents operation above -18°C (0°F). A weather shield on the cord is provided to protect the plug when not in use.

Reference Information

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

Circuit/System Testing

Note: The coolant heater cord will read Open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).

1. Ignition OFF, disconnect the coolant heater cord from the E19 Coolant Heater.

2. Test for 30-40 ohms between the terminals of the E19 Coolant Heater.

• If not within 30-40 ohms
Replace the E19 Coolant Heater.

• If within 30-40 ohms

3. Test for infinite resistance between each terminal of the E19 Coolant Heater and ground.

• If less than infinite resistance
Replace the E19 Coolant Heater.

• If infinite resistance

4. Test or replace the coolant heater cord.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic repair.

* Engine Coolant Heater Replacement (LFX) Engine Coolant Heater Replacement

* Coolant Heater Cord Replacement (LFX) Coolant Heater Cord Replacement