For 1990-2009 cars only
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 Pump Control | B0445 00 | B0447 00 | B0446 00 | -- |
Coolant Heater Fuel Pump Ground | -- | B0447 00 | -- | -- |
Circuit/System Description
The fuel operated coolant heater uses a fuel pump to supply fuel to the combustion chamber.
Conditions for Running the DTC
Engine is running.
Conditions for Setting the DTC
The fuel operated heater has recognized out of range condition for more 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
Ignition ON, command the Auxiliary Heater Fuel Pump ON and OFF with the scan tool. Verify the fuel pump turns ON and OFF as commanded.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the fuel pump.
- Ignition OFF, test for less than 5 ohms between the ground circuit terminal 1 and ground.
- Install a test lamp between the control circuit terminal 2 and ground circuit terminal 1.
- Ignition ON, command the fuel pump 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 fuel pump.
| ⇒ | 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.
