B0442

DTC B0440, B0441, or B0442

Diagnostic Instructions

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

DTC Descriptors

DTC B0440 00
- Auxiliary Heater Glow Plug Circuit Low

DTC B0441 00
- Auxiliary Heater Glow Plug Circuit High

DTC B0442 00
- Auxiliary Heater Glow Plug Circuit Open

Diagnostic Fault Information






Circuit/System Description

The fuel operated coolant heater uses a heater glow plug to increase the temperature in the combustion chamber to a temperature that is necessary to ignite the air fuel mixture. Once a stable flame has formed, the glow plug will turn OFF.

Conditions for Running the DTC

Engine is running.

Conditions for Setting the DTC

Fuel operated coolant heater has recognized out of range condition for more than 2.5 seconds.

Action Taken When the DTC Sets

Fuel operated coolant heater is disabled.

Conditions for Clearing the DTC

DTC must be cleared with a scan tool.


Circuit/System Verification

Start the vehicle. Observe the Glow Plug Sensor On scan tool parameter. When the glow plug is activated, the scan tool should read near battery voltage.

Component Testing

1. With the ignition ON and the glow plug not commanded ON, probe the control circuit of the glow plug with a test lamp connected to ground. Observe that the test lamp does not illuminate.

^ If the test lamp does illuminate, test the glow plug control circuit for a short to voltage.. Replace the affected glow plug after repair.

2. With the ignition ON, probe the glow plug with a test lamp connected to ground. Command the glow plug ON with a scan tool and observe the test lamp. The test lamp should illuminate.

^ If the test lamp does not illuminate, test the glow plug harness between the glow plug control module and the glow plug for an open, short to ground or high resistance.

3. With the ignition OFF and the glow plug disconnected, measure the resistance across the glow plug with a DMM for less than 1 ohm.

^ If the resistance is more than 1 ohm, replace the glow plug.

4. With the ignition ON and the glow plug disconnected, connect a test lamp between the control circuit and the ground circuit of the glow plug. Command the glow plug ON with a scan tool and observe the test lamp. The test lamp should illuminate.

^ If the test lamp does not illuminate, test the glow plug ground circuit between the coolant heater and the glow plug for an open, high resistance.
^ If the circuit tests normal, replace the coolant heater.

Repair Instructions

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

* Heater Coolant Heater Glow Plug Replacement
* Heater Coolant Heater Replacement