Coolant Heater Inoperative Diesel
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 each diagnostic category. |
Circuit/System Description
The optional coolant heater operates using 110 volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. There are two heater cords available. One has an internal thermal switch in the power cord that prevents operation above -18°C (0°F) and the other operates at all temperatures. A weather shield on the cord is provided to protect the plug when not in use.
Reference Information
Electrical Information Reference
Circuit/System Testing
Important: The heater cord with a thermal switch will read open if the ambient temperature is above -18°C (0°F). A heater cord without a thermal switch can be tested for an open at any temperature.
- Test the engine coolant heater for an open or short to ground.
- If the heater tests normal, replace the coolant heater power cord.
| ⇒ | If open or shorted, replace the heater. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Coolant Heater Inoperative Gas
Test Description
Step | Action | Yes | No |
|---|---|---|---|
Connector End View Reference: Cooling System Connector End Views | |||
1 | Did you perform the necessary inspections? | Go to Step 2 | |
|
Important: The power supply cord will read open if the ambient temperature is above -1°F (-18°C). Test the engine coolant heater power supply cord for an open or short to ground. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | Go to Step 3 | Go to Step 4 | |
3 | Replace the engine coolant heater power supply cord. Refer to Coolant Heater Cord Replacement . Did you complete the repair? | Go to Step 6 | -- |
4 | Inspect for poor connections at the harness connector of the engine coolant heater. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 | Replace the engine coolant heater. Refer to Coolant Heater Replacement . Did you complete the repair? | Go to Step 6 | -- |
6 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
