Cabin Heater Module (CHM) and Heater Booster Module (HBM)

CABIN HEATER MODULE (CHM) AND HEATER BOOSTER MODULE (HBM)

SYSTEM DESCRIPTION

WARNING:
- NEVER OPERATE THE HEATER IN AN ENCLOSED AREA THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS VENT THE HEATER'S EXHAUST WHEN OPERATING THE HEATER. REFER TO (VENTING THE HEATER'S EXHAUST( BELOW FOR PROPER EXHAUST VENTING INSTRUCTIONS. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
- ALLOW THE HEATER ASSEMBLY TO COOL BEFORE PERFORMING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
- ALWAYS DISCONNECT THE VEHICLE'S BATTERY PRIOR TO PERFORMING ANY TYPE OF WORK ON THE HEATER ASSEMBLY. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
- NEVER ATTEMPT TO REPAIR THE HEATER ASSEMBLY OR ANY OF ITS INTERNAL COMPONENTS. ALWAYS PERFORM HEATER COMPONENT REPLACEMENT. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.

CAUTION: Always Perform The Heater Pre-Test (In The Diagnostic Procedures) Prior To Performing Any Other Test On The Heater For The Test Result To Be Valid.

NOTE:
- Do not disconnect the vehicle's battery or the heater's main power-supply while the heater is in operation or in run-down mode. Failure to follow these instructions may result in excess emissions from the heater.
- Failure to prime the Dosing Pump after draining the fuel line will prevent heater activation during the first attempt to start the unit. This may also set a Diagnostic Trouble Code (DTC) in the control unit's memory. Do not perform the Dosing Pump Priming Procedure if an attempt was made to start the heater without priming the Dosing Pump first. This will put excess fuel in the heater module and cause smoke to emit from the heater's exhaust pipe when heater activation occurs.
- Waxed fuel can obstruct the fuel line and reduce flow. Check for the appropriate winter grade fuel and replace as necessary.

The Cabin Heater Assembly and Heater Booster Assembly are supplemental type heaters designed to pre-heat the engines coolant in order to supply the vehicle's occupants with heat prior to the engine reaching operating temperature. The heater's control unit controls and monitors combustion operation through various inputs and outputs that are contained inside the heater assembly. The supplemental heater connects to the vehicle's heater hoses and uses a separate fuel supply line and fuel pump that connects to the vehicle's fuel tank. Unlike the Heater Booster, the Cabin Heater Assembly has an integral coolant pump which allows heater operation without the vehicle's engine running. In addition, a programmable timer module can also be added to this system. Neither the Cabin Heater Assembly nor the Heater Booster Assembly are connected to the CAN Bus. Communication between the heater's control unit and the DRBIII(R) occurs through the Diagnostic Link Connector (DLC) via a K-Line.

VENTING THE HEATER'S EXHAUST

WARNING:
- NEVER OPERATE THE HEATER IN AN ENCLOSED AREA THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS VENT THE HEATER'S EXHAUST WHEN OPERATING THE HEATER. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
- ALLOW THE HEATER ASSEMBLY TO COOL BEFORE PERFORMING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.

CAUTION: When using a powered exhaust ventilation system, do not attach the exhaust ventilation hose directly to the heater's exhaust pipe. Too much suction can prevent heater operation.

When using a powered exhaust ventilation system, affix the ventilation hose to the heater's exhaust pipe or to the vehicle in such a manor that the end of the ventilation hose remains approximately three inches away from the end of the heater's exhaust pipe.

When using a non-powered exhaust ventilation system, affix the ventilation hose directly to the heater's exhaust pipe.

SYSTEM DIAGNOSTICS

CAUTION: Always Perform The Heater Pre-Test (In The Diagnostic Procedures) Prior To Performing Any Other Test For The Test Result To Be Valid.

Fault detection is through stored Diagnostic Trouble Codes (DTCs). DTCs are displayed by the DRBIII(R). The hetaeras control unit will store up to five DTCs in its memory. If the control unit detects a new fault in the system, one that is not already stored in its memory, it will clear the oldest of the five stored DTCs, and it will store the new fault's DTC. If the control unit detects a reoccurrence of a stored fault, it will overwrite that fault's DTC with the most recent occurrence.
DIAGNOSTIC TIPS

SENSOR VALUES

Operating Voltage
The normal range for the Operating Voltage is from 10 volts to 15 volts. The value indicates the voltage at the heater's Fused B+ terminal.

Heating Capacity
The normal range for the heating capacity is from 0% to 100%. The value indicates the momentary output of the auxiliary heater in % of the maximum output.

Coolant Temperature
The value indicates the current coolant temperature.

Flame Sensor Resistance
The normal range for the Flame Sensor is from 750 ohms to 2270 ohms. The value indicates the momentary resistance of the Flame Sensor.

INPUT/OUTPUT STATUS

Dosing Pump
A status of "ON" indicates that the Dosing Pump is operational. A status of "OFF" indicates the Dosing Pump is not operational.

Glow Pin
A status of "ON" indicates that the Glow Pin is energized. A status of "OFF" indicates the Glow Pin is not energized.

Combustion Fan
A status of "ON" indicates that the Combustion Fan is operational. A status of "OFF" indicates the Combustion Fan is not operational.

Circulation Pump
A status of "ON" indicates that the Circulation Pump is operational. A status of "OFF" indicates the Circulation Pump is not operational.

Front End Blower
A status of "ON" indicates that the Blower Motor is operational. A status of "OFF" indicates the Blower Motor is not operational.

Static Heater Signal
A status of "ON" indicates that the heater module sees the "Stationary Heating Mode "ON" signal after switching on the heater with the heater timer or the auxiliary heater switch. A status of "OFF" indicates that the "Stationary Heating Mode "ON" signal is not present at the heater module.

Heater Booster Mode Signal
A status of "ON" indicates that the heater module sees the "Heater Booster Mode ON" signal after switching on the heater with the auxiliary heater switch. A status of "OFF" indicates that the "Heater Booster Mode ON" signal is not present at the heater module.