For 1990-2009 cars

## Coolant Heater Inoperative V6

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of the diagnostic category.

### Circuit/System Description

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

### Reference Information

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

Note: The power supply cord will test open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).

1. Test the engine coolant heater for an open or short to ground.

⇒ | If open or shorted, replace the heater.

2. If the heater tests normal, replace the coolant heater power cord.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.