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 B0445 00 : Auxiliary Heater Fuel Pump Circuit LowDTC B0446 00 : Auxiliary Heater Fuel Pump Circuit High
DTC B0447 00 : Auxiliary Heater Fuel Pump Circuit Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Auxiliary Heater Fuel Plug Circuit | B0445 00 | B0447 00 | B0446 00 | B0445 00, B0446 00, B0447 00 |
Coolant Heater Fuel Pump Circuit | - | B0447 00 | B0446 00 | B0445 00, B0446 00, B0447 00 |
Circuit/System Description
The fuel operated heater uses an auxiliary heater fuel pump to supply fuel to the combustion chamber through the glow plug socket over the glow plug 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 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.
Reference Information
Schematic Reference
Connector End View Reference
Cooling System Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Start the vehicle. Observe the Coolant Heater Fuel Pump and desired fuel pump scan tool parameters . The scan tool parameters should match. Above 85°C (185°F), the coolant heater will no longer pump fuel. Above 80-85°C (176-185°F), the coolant pump will operate at a reduced level. Above 20-75°C (68-176°F), the coolant pump will operate at full capacity.
Component Testing
- Ignition OFF, disconnect the 10-pin coolant heater module pigtail connector from the module.
- Test the coolant heater fuel pump resistance.
- Compare the readings with the Temperature vs Resistance table and verify that the resistance is within 5 percent of the specification.
- If the coolant heater fuel pump tests normal, replace the coolant heater.
| ⇒ | If the resistance vs temperature reading is not within 5 percent, replace the coolant heater fuel pump. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
