Auxiliary Heater Control Module (AHCM) Trouble Code (Freelander 2)

Auxiliary climate control module

NOTE: If a module or component failure is suspected and the vehicle remains under manufacturer's warranty, refer to the Warranty Guide (Section B1.2) or determine if there is a previously approved special program in effect before replacing the component.

NOTE: Generic scan tools may not be able to read the codes listed or may only be able to read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7-digit code to identify the fault (the last 2 digits provide additional information readable by the manufacturer-approved diagnostic system).

NOTE: When performing voltage or resistance tests, always use a digital multimeter (DMM) with three decimal places of accuracy and a valid calibration certificate. When testing resistance, be sure to include the resistance of the DMM leads.

NOTE: Before starting diagnostic programs using fault location tests, check and correct basic faults.

NOTE: Inspect the connectors for signs of water ingress and their pins for damage and/or corrosion.

NOTE: If DTCs are set and the fault is not present after performing the troubleshooting tests, an intermittent problem may be the cause. Be sure to check for loose connections and corroded terminals.

Description and operation

For a detailed description of the operation of the fuel-fired auxiliary heater control system, refer to the relevant section on the system description and operation in the workshop manual. For additional information, refer to the chapter: Auxiliary Fuel-Fired Heater (412-02 Additional Climate Control, Description and Operation).

NOTE: The "On Demand Self Test" feature can be accessed via the "DTC Monitor" tab on the manufacturer approved diagnostic system.

DTC	Description	Possible reasons	Action
B1D22-11	Coolant Temperature Sensor Circuit: Short to Ground	Internal malfunction of the temperature sensor of the additional liquid fuel heater	Check and install a new coolant temperature sensor for the liquid fuel auxiliary heater Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes Check if it works correctly
B1D22-15	Coolant Temperature Sensor Circuit: Short to Battery Positive or Open Circuit	Internal malfunction of the temperature sensor of the additional liquid fuel heater	Check and install a new coolant temperature sensor for the liquid fuel auxiliary heater Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes Check if it works correctly
B1D23-13	Overheating sensor: open circuit	Internal malfunction of the temperature sensor of the additional liquid fuel heater	Check and install a new coolant temperature sensor for the liquid fuel auxiliary heater Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes Check if it works correctly
B1D24-11	Glow Plug Circuit: Short to Ground	Internal failure of the glow plug of the liquid fuel auxiliary heater	Check the circuits, inspect the wires and the glow plug connector. Repair the circuit or check and install a new glow plug of the liquid fuel supplemental heater (if necessary). For more information, refer to the chapter: Glow Plug and Burner of the Fuel-Fired Supplemental Heater (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes Check if it works correctly
B1D24-15	Glow plug circuit: short circuit to battery positive or open circuit	Internal failure of the glow plug of the auxiliary liquid fuel heater	Check the circuits, inspect the wires and the glow plug connector. Repair the circuit or check and install a new glow plug of the liquid fuel supplemental heater (if necessary). For more information, refer to the chapter: Glow Plug and Burner of the Fuel-Fired Supplemental Heater (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check if it works correctly
B1D25-11	Heater Fuel Pump Circuit: Short to Ground	Heater Fuel Pump Electrical Circuit: Short to Ground Heater fuel pump: malfunction	Refer to the electrical diagrams to check the fuel pump and booster heater circuit for a short to ground. Repair the circuit or check and install a new fuel fired auxiliary heater fuel pump (if necessary). For more information, refer to the chapter: Fuel Pump for Fuel Fired Auxiliary Heater (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check if it works correctly
B1D25-15	Heater Fuel Pump Circuit: Short to Battery Positive or Open Circuit	Heater Fuel Pump Electrical Circuit: Short to Power or Open Circuit Heater fuel pump: malfunction	Refer to electrical diagrams to check fuel pump and booster heater circuit for short to power, open circuit. Repair the circuit or check and install a new fuel fired auxiliary heater fuel pump (if necessary). For more information, refer to the chapter: Fuel Pump for Fuel Fired Auxiliary Heater (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D26-11	Combustion Air Injection Fan Circuit: Short to Ground	Fuel fired auxiliary heater control module: malfunction	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). If the diagnostic trouble code returns, check and install a new fuel fired auxiliary heater module. For additional information, refer to: Fuel Fired Auxiliary Heater (412-02 Auxiliary Climate Control, Removal and Installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
B1D26-15	Combustion Air Blower Circuit: Short to Battery Positive or Open Circuit	Fuel fired auxiliary heater control module: malfunction	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). If the diagnostic trouble code returns, check and install a new fuel fired auxiliary heater module. For additional information, refer to: Fuel Fired Auxiliary Heater (412-02 Auxiliary Climate Control, Removal and Installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
B1D26-92	Combustion air supply fan: not working or not working properly	Fuel fired auxiliary heater control module: malfunction	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for re-registration of the diagnostic trouble code. If the diagnostic trouble code returns, check and install a new fuel fired auxiliary heater module. For additional information, refer to: Fuel Fired Auxiliary Heater (412-02 Auxiliary Climate Control, Removal and Installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
B1D26-93	Combustion air supply fan: not working	Fuel fired auxiliary heater control module: malfunction	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for re-registration of the diagnostic trouble code. If the diagnostic trouble code returns, check and install a new fuel fired auxiliary heater module. For additional information, refer to: Fuel Fired Auxiliary Heater (412-02 Auxiliary Climate Control, Removal and Installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
B1D27-11	Heater Coolant Pump: Short to Ground Circuit	Heater coolant pump electrical circuit: short circuit to ground. Heater coolant pump: malfunction.	Refer to the electrical diagrams to check the water pump and booster heater circuit for a short to ground. Repair the circuit or check and install a new fuel-fired auxiliary heater water pump (if necessary). For more information, refer to the chapter: Fuel-Fired Auxiliary Heater Coolant Pump (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D27-15	Heater Coolant Pump Circuit: Short to Battery Positive or Open Circuit	Heater coolant pump electrical circuit: short circuit to power supply or open circuit. Heater coolant pump: malfunction.	Refer to electrical diagrams to check water pump and booster heater circuit for short to power, open circuit. Repair the circuit or check and install a new fuel-fired auxiliary heater water pump (if necessary). For more information, refer to the chapter: Fuel-Fired Auxiliary Heater Coolant Pump (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D28-11	Fuel preheater: short circuit to ground	NOTE: Preheating is performed by a glow plug. Internal failure of the glow plug of the liquid fuel auxiliary heater	Check the circuits, inspect the wires and the glow plug connector. Check and install a new liquid fuel supplemental heater glow plug (if necessary). For more information, refer to the chapter: Fuel Fired Supplemental Heater Glow Plug and Burner (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check if it works correctly
B1D28-15	Fuel Preheater: short circuit to a positive battery cell or circuit break	NOTE: Preheating is performed by a glow plug. Internal failure of the glow plug of the liquid fuel auxiliary heater.	Check the circuits, inspect the wires and the glow plug connector. Check and install a new liquid fuel supplemental heater glow plug (if necessary). For more information, refer to the chapter: Fuel Fired Supplemental Heater Glow Plug and Burner (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check if it works correctly
B1D29-93	Launch does not occur even after repeated attempt: does not work	There is no fuel in the fuel fired auxiliary heater. Exhaust system blockage. Blockage of the air intake system.	Check the fuel level. Check the fuel fired booster heater (FFBH) module fuel lines for blockages, kinks, or damage. Check the exhaust system and air intake system for blockages, pinching or damage. Check fuel for aeration, troubleshoot fuel supply problems. When turning on the parking heater, make sure that the vehicle is not parked on a slope. Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D30-93	Unable to run in check mode: not working	There is no fuel in the fuel fired auxiliary heater. Exhaust system blockage. Blockage of the air intake system.	Check the fuel level. Check the fuel fired booster heater (FFBH) module fuel lines for blockages, kinks, or damage. Check the exhaust system and air intake system for blockages, kinks or damage. Check fuel for aeration, troubleshoot fuel supply problems. When turning on the parking heater, make sure that the vehicle is not parked on a slope. Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check if it works correctly
B1D31-94	Flame detected before normal operation: unexpected action	NOTE: The glow plug and flame sensor are a single unit. Glow plug circuit malfunction	Check the exhaust system and air intake system for blockages, kinks or damage. Check the circuits, inspect the wires and the glow plug connector. Repair the circuit or check and install a new glow plug of the liquid fuel supplemental heater (if necessary). For more information, refer to the chapter: Glow Plug and Burner of the Fuel-Fired Supplemental Heater (412-02 Auxiliary Climate Control, Removal and Installation). Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D32-92	Flame repeatedly interrupted during preheat cycle - not working or not working properly	There is no fuel in the fuel fired auxiliary heater. Exhaust system blockage. Blockage of the air intake system.	Check the fuel level. Check the fuel fired booster heater (FFBH) module fuel lines for blockages, kinks, or damage. Check the exhaust system and air intake system for blockages, kinks or damage. Check fuel for aeration, troubleshoot fuel supply problems. When turning on the parking heater, make sure that the vehicle is not parked on a slope. Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D33-92	Flame interruption during normal operation: does not work or does not work properly	There is no fuel in the fuel fired auxiliary heater. Exhaust system blockage. Blockage of the air intake system.	Check the fuel level. Check the fuel fired booster heater (FFBH) module fuel lines for blockages, kinks, or damage. Check the exhaust system and air intake system for blockages, kinks or damage. Check fuel for aeration, troubleshoot fuel supply problems. When turning on the parking heater, make sure that the vehicle is not parked on a slope. Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D34-68	Heater in Lockout Mode: Event Information	Malfunction of the liquid fuel auxiliary heater system	NOTE: Information only: Correct any other stored liquid fuel heater DTCs before correcting the fault associated with this code. Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for stored diagnostic trouble codes. Check that it works correctly.
B1D63-11	External control relay: short circuit to ground	Fuel fired auxiliary heater control module: malfunction	Check and install a new fuel fired auxiliary heater module if necessary. For more information, refer to the chapter: Fuel fired auxiliary heater (412-02 Auxiliary climate control, Removal and installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
B1D63-15	External control relay - short circuit to battery or open circuit	Fuel fired auxiliary heater control module: malfunction	Check and install a new fuel fired auxiliary heater module if necessary. For more information, refer to the chapter: Fuel fired auxiliary heater (412-02 Auxiliary climate control, Removal and installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program
U0010-00	Medium Speed CAN Communication Bus: No subtype information available	Disabling the medium-speed CAN communication bus	Perform a CAN bus integrity check using the manufacturer approved diagnostic system.
U0028-08	Communication Bus A: Bus signal/message failure	Disabling the medium-speed CAN communication bus. Fuel fired auxiliary heater control module: malfunction.	Perform a CAN bus integrity check using the manufacturer approved diagnostic system.
U0300-00	Internal control unit software incompatibility: no subtype information	Fuel fired auxiliary heater: not set up or set up incorrectly	Using the manufacturer approved diagnostic system, reprogram the liquid fuel booster heater module (Unit Programming/Configure Existing Unit/Booster Heater Control Unit)
U1A37-87	Bus Crash Signal/Message Failure: No Message	Received a collision signal via CAN network	NOTE: Event information: A collision has been detected in the SRS control unit. Using the manufacturer approved diagnostic system, check other modules for related diagnostic trouble codes.
U2101-00	Incompatible control unit configuration: no subtype information	Fuel fired auxiliary heater: not set up or set up incorrectly. The central distribution box is not set up correctly.	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for re-registration of the diagnostic trouble code. In case of repeated registration of the diagnostic trouble code. If necessary, check and update the vehicle configuration file using a manufacturer approved diagnostic system. Reconfigure the fuel fired auxiliary heater using the manufacturer approved diagnostic system. Check for stored diagnostic trouble codes. Check that it works correctly.
U3000-16	Control unit: voltage in circuit below threshold	Malfunction of the power supply circuit of the fuel-fired auxiliary heater module. Battery or charging system failure.	Check other modules for related diagnostic trouble codes. If diagnostic trouble codes related to low voltage are registered in other modules, a common fault may occur (battery / charging system malfunction). Otherwise, using the electrical diagrams, check the power and ground circuits connected to the fuel fired booster heater (FFBH) control unit. Check for stored diagnostic trouble codes. Check that it works correctly.
U3000-17	Control unit: voltage in circuit above threshold	Charging system malfunction. Fuel fired auxiliary heater control module: malfunction.	Check other modules for related diagnostic trouble codes. If diagnostic trouble codes related to high voltage are registered in other modules, a common fault may occur (battery / charging system malfunction). Otherwise, using the electrical diagrams, check the power and ground circuits connected to the fuel fired booster heater (FFBH) control unit. Check for stored diagnostic trouble codes. Check that it works correctly.
U3000-43	Control unit: special memory failure	Fuel fired auxiliary heater control module: malfunction	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for re-registration of the diagnostic trouble code. In case of repeated registration of the diagnostic trouble code. If necessary, install a new fuel fired auxiliary heater module. For more information, refer to the chapter: Fuel fired auxiliary heater (412-02 Auxiliary climate control, Removal and installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
U3000-49	Control unit: internal electronic equipment failure	Fuel fired auxiliary heater control module: malfunction	Using the manufacturer approved diagnostic system, record and then clear stored diagnostic trouble codes; after this, perform a running test of the fuel-fired auxiliary heater ("Installation and adjustment/auxiliary heater/running test"). Check for re-registration of the diagnostic trouble code. In case of repeated registration of the diagnostic trouble code. If necessary, install a new fuel fired auxiliary heater module. For more information, refer to the chapter: Fuel fired auxiliary heater (412-02 Auxiliary climate control, Removal and installation). Before installing a new unit/component, please refer to the warranty and procedures manual to determine if the replacement requires prior authorization under any applicable special program.
U3003-62	Battery Voltage: Signal Comparison Error	The difference between the power supply of the fuel-fired auxiliary heater and the battery voltage value transmitted via the CAN bus is more than 2 V	Check other modules for related diagnostic trouble codes. If voltage related diagnostic trouble codes are logged in other modules, a common fault (battery/charging system fault) may be present. Otherwise, using the electrical diagrams, check the power and ground circuits connected to the fuel fired booster heater (FFBH) control unit.