B0446

DTC B0446

DTC DESCRIPTORS

DTC B0445 00
Auxiliary Heater Fuel Pump Circuit Low

DTC B0446 00
Auxiliary Heater Fuel Pump Circuit High

DTC B0447 00
Auxiliary Heater Fuel Pump Circuit Open

DIAGNOSTIC FAULT INFORMATION






IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

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 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 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
1. Ignition OFF, disconnect the 10-pin coolant heater module pigtail connector from the module.
2. Test the coolant heater fuel pump resistance.
3. Compare the readings with the Temperature vs Resistance table and verify that the resistance is within 5 percent of the specification.
- If the resistance vs temperature reading is not within 5 percent, replace the coolant heater fuel pump.
4. If the coolant heater fuel pump tests normal, replace the coolant heater.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Cell link coolant heater fuel pump

Cell link replace the coolant heater