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. |
DTC Descriptors
DTC B0440 00: Auxiliary Heater Glow Plug Circuit LowDTC B0441 00: Auxiliary Heater Glow Plug Circuit High
DTC B0442 00: Auxiliary Heater Glow Plug Circuit Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Heater Glow Plug Control | B0440 00 | B0442 00 | B0441 00 | -- |
Heater Glow Plug Low Reference | -- | B0442 00 | -- | -- |
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 will 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
The fuel operated coolant heater has recognized out of range condition for greater than 2.5 seconds.
Action Taken When the DTC Sets
The fuel operated coolant heater is disabled.
Conditions for Clearing the DTC
| • | A current DTC will clear when the conditions for setting the DTC are no longer present. |
| • | A history DTC will clear after 40 malfunction-free ignition cycles. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Air Temperature Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Engine running, observe the scan tool Glow Plug Command parameter. When the glow plug is activated, the scan tool should display On.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the glow plug.
- Ignition OFF, test for less than 5 ohms between the low reference circuit terminal and ground.
- Install a test lamp between the control circuit terminal and low reference circuit terminal.
- Ignition ON, command the glow plug ON and OFF using a scan tool. Verify the test lamp turns ON and OFF with each command.
- If all circuits test normal, test or replace the glow plug.
| ⇒ | If greater than the specified range, replace the coolant heater. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the coolant heater. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or 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.
