B0452

DTC B0449, B0450, B0451, or B0452

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC B0449 00
- Auxiliary Heater Blower Fan Circuit Range/Performance

DTC B0450 00
- Auxiliary Heater Blower Fan Circuit Low

DTC B0451 00
- Auxiliary Heater Blower Fan Circuit High

DTC B0452 00
- Auxiliary Heater Blower Fan Circuit Open

Diagnostic Fault Information






Circuit/System Description

The fuel operated heater uses a coolant heater blower motor to supply oxygen onto the combustion chamber so the air fuel mixture will ignite when the glow plug is activated.

Conditions for Running the DTC

Engine is running.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

Fuel operated heater is disabled.

Conditions for Clearing the DTC

DTC must be cleared with a scan tool.


Circuit/System Verification

Start the vehicle. Observe the Blower Motor Feedback Circuit scan tool parameter. The scan tool parameters should display On when the heater is activated.

Component Testing

1. Ignition OFF, disconnect the harness connector at the coolant heater blower motor.
2. Test for less than 10 ohms between the ground circuit and ground.

^ If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit and the ground circuit.
4. Command the coolant heater blower motor ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

^ 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.

5. If all circuits test normal, test or replace the coolant heater blower motor.

Repair Instructions

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

* Heater Coolant Heater Blower Replacement
* Heater Coolant Heater Replacement