64 01 05 (135) Independent Heating
64 01 05 (135)
Independent heating
E70, E90, E91, E92, E93
Introduction
The independent heating (made by Webasto) will be installed for the first time on the E90, E91 from 09/2005. The independent heating comprises the independent auxiliary heater and the associated components and power supply.
The independent heating is incorporated in the integrated automatic heating/air-conditioning system (IHKA).
E70: heating and air-conditioning system controlled on the water side.
E90, E91, E92, E93: heating and air-conditioning system controlled on the air side.
The independent heating is optional (option 536).
- E70 [system overview ...]
- E90, E91, E92, E93 [system overview ...]
The main element of the new independent auxiliary heater is a Venturi burner. This optimises the entire combustion process to make it considerably more efficient than compared to previous burner technology.
Advantages of the new independent auxiliary heater compared to the auxiliary heater units previously used at BMW:
- Faster start-up and shut-down procedure
- More rapid stabilisation of the combustion process
(the maximum heating capacity (5 kW) can therefore be reached faster)
- Weight of auxiliary heater unit reduced by approx. 20 %
- The auxiliary heating system requires approx. 30 % less space in the vehicle
Brief description of components
The following components send signals to the auxiliary heating system:
- Telestart transmitter
The Telestart transmitter sends the signal to switch the auxiliary heating on and off to the CAS control unit.
- Temperature sensor in auxiliary heater circuit
The temperature sensor in the auxiliary heater registers the temperature in the heating circuit. The signal is processed in the control unit for the auxiliary heater. The control unit therefore controls full-load operation, part-load operation and control pause.
- Temperature sensor for overtemperature protection
The temperature sensor in the auxiliary heater registers the operating temperature. The overtemperature protection facility protects the auxiliary heater from impermissibly high operating temperatures.
The following control units are involved in the auxiliary heating system:
- IHKA control panel and IHKA control unit
The IHKA controls and the IHKA control unit are combined in a single component.
The IHKA control unit is connected to the K-CAN and LIN bus.
The IHKA control unit outputs all the requests for the independent heating function as a message on the K-CAN and the LIN bus.
A flashing symbol in the display indicates when the independent heating is in operation.
From terminal R it is possible to specify the desired interior temperature for the independent heating function during independent heating operation at the IHKA controls. The set temperature is shown in the display of the IHKA control panel.
- JBE: Junction box electronics
The JBE is an integral part of the junction box. The junction box consists of the JBE and the power distributor. The power distributor provides the power for the auxiliary heater.
The JBE is connected via the K-CAN to the bus system.
E70
Note: The JBE controls the water valve for metering the throughflow of coolant to the heat exchanger.
The water valve works electromagnetically and meters the coolant flow rate to the heating system heat exchanger as it is needed. This determines the temperature of the air used for heating the vehicle interior.
In the case of automatic air conditioning with separate adjustment for the driver and passenger sides, a duo water valve is installed on account of the left/right separation of the heat exchanger.
E90, E91, E92, E93
Note: The JBE controls the water valve and the auxiliary water pump.
The water valve controls the supply to the independent auxiliary heater either from the radiator supply or from the heat exchanger return flow.
In the E70 the switchover valve controls the supply to the independent auxiliary heater.
Activation is effected on the prompt of the IHKA control unit via the K-CAN.
- CAS: Car Access System
The Telestart receiver receives the radio signals from the Telestart transmitter and forwards them to the CAS control unit. In turn, the CAS control unit sends a message on the K-CAN.
Signal path: Telestart transmitter -> Telestart antenna -> Telestart receiver -> direct wire -> CAS -> K-CAN -> IHKA control unit -> LIN bus -> SHZH control unit
- DME or DDE: Digital motor electronics or digital diesel electronics
> E90, E91, E92, E93
The DME or DDE sends the message to switch the water valve on and off. The water valve or switchover valve is switched on and off depending on the coolant temperature.
- M-ASK or CCC or CHAMP: Multi-audio system controller or Car Communication Computer or multimedia platform
The controller signals for selecting the menu are processed in the M-ASK or CCC or CHAMP (multimedia platform: CHAMP; Central Head Unit and Multimedia Platform).
- CON and CID: Controller and Central Information Display
Operation of the auxiliary heater is selected and activated with the controller in the CID.
Selection: Direct operation or programming using timer
E90, E91, E92, E93
Note: Activation of auxiliary heating by BMW "Professional" radio
If no CID is installed, operation of the auxiliary heating system can be activated by means of option 663 " BMW Professional radio".
Selection: Direct operation or programming using timer
- KOMBI: Instrument cluster
The instrument cluster sends the outside temperature and the time in the form of a message on the K-CAN. The instrument cluster manages the timer function in the event of timer programming.
The following components are controlled:
- SHZH: Independent/auxiliary heater
A control unit is installed in the independent auxiliary heater. The SHZH control unit controls and monitors independent auxiliary heating operation. The SHZH control unit is actuated by the IHKA control unit via the LIN bus.
> E70
> E90, E91, E92, E93
- Fuel metering pump
The metering pump supplies fuel to the auxiliary heater (diesel or petrol). The SHZH control unit directly controls the metering pump. The metering pump is installed on the vehicle underbody in the vicinity of the fuel tank.
Note: Independent auxiliary heater with new metering pump in E90, E91 with diesel engine
As from 09/2006 vehicles with diesel engines will feature an independent auxiliary heater with a new metering pump. An additional valve has been installed in the independent auxiliary heater. This valve prevents diesel fuel from overrunning unmonitored in the combustion chamber (e.g. due to thermal expansion of the fuel). The metering pump has been adapted accordingly.
Thus, when an "old" independent auxiliary heater (up to 09/2006 without additional valve) must be replaced by a "new" independent auxiliary heater (from 09/2006 with additional valve), it is also necessary to replace the metering pump.
If only the metering pump is replaced, it is important to pay attention to the part number (metering pump for independent auxiliary heater without additional valve or metering pump for independent auxiliary heater with additional valve).
- Auxiliary water pump
E90, E91, E92, E93
The auxiliary water pump serves the purpose of providing the necessary flow of coolant through the heating circuit at low engine speeds and/or in auxiliary heating mode.
The auxiliary water pump is actuated by the junction box electronics (JBE). The IHKA control unit provides the signal to switch the auxiliary water pump on and off.
The auxiliary water pump is installed on the frame side member at the level of the left suspension strut tower.
- Vehicles with 6-cylinder petrol engine N52
Vehicles with the N52 engine are equipped with an electric coolant pump. These vehicles therefore have an auxiliary water pump only if they are equipped with option 536 "Auxiliary heating".
The auxiliary water pump is installed on the auxiliary heater in the heating circuit.
E70
If option 536 "Independent heating" is installed, then the auxiliary water pump is omitted. The function is assumed by the circulating pump on the independent heating.
- Water valve
E90, E91, E92, E93
The water valve is installed only in connection with option 536 "Independent heating".
The water valve and auxiliary water pump are combined to form one component.
The water valve controls the supply to the independent auxiliary heater as follows:
- From the radiator feed
or
- From the return flow from the heating system heat exchanger
(In the E70 the switchover valve controls the supply to the independent auxiliary heater.)
The junction box electronics (JBE) actuates the water valve. The switch-on and switch-off message comes from the DME or DDE as well as from the IHKA control unit.
The water valve with auxiliary water pump is installed on the frame side member at the level of the left suspension strut tower.
- Vehicles with 6-cylinder petrol engine N52
The water valve is installed on the frame side member at the level of the left suspension strut tower. (The auxiliary water pump is installed on the auxiliary heater in the heating circuit.)
- Switchover valve
E70
The switchover valve is installed only in conjunction with option 536 "Independent heating".
The switchover valve controls the supply to the independent heating as follows:
- From the radiator feed
or
- From the return flow from the heating system heat exchanger
The SHZH control unit directly activates the switchover valve. The switch-on and switch-off message comes from the DME or DDE as well as from the IHKA control unit.
System functions
The auxiliary heating system incorporates the following functions:
- Switch-on
- Auxiliary heating operation
- Pseudo auxiliary heating mode with engine running
- Low-voltage cutout (via DME/DDE)
- Overtemperature protection
- Switch-off
Switch-on
The independent heating function is activated either via the Central Information Display (CID) or via Telestart (through the Car Access System (CAS)).
There are 2 ways of activating the system via the CID: Direct operation or programming using the timer.
In connection with Telestart (via CAS) the average range of the Telestart transmitter is approx. 150 metres.
The range of the Telestart transmitter is limited:
- by obstructions
- by outside irradiation
- by the orientation of the aerial
When switching on the independent heating, point the Telestart transmitter vertically upwards.
The LED flashing in the Telestart transmitter does not constitute a verification that the independent heating has been activated.
The CAS forwards the signal from the Telestart transmitter via the body CAN to the IHKA control unit.
In term, the IHKA control unit sends the message via the LIN bus to the auxiliary heater control unit.
When the independent heating is switched on, glow plug, combustion-air fan and auxiliary water pump (E90, E91, E92, E93) or circulating pump (E70) are activated.
The metering pump cuts in after approx. 30 seconds. The flame then ignites within 3 seconds and the auxiliary heating runs in full load mode.
The starting time is approx. 120 to 180 seconds (starting time: time between switching on and full load operation).
Automatically controlled heating operation now begins.
At very low outside temperatures, mist may form at the exhaust outlet of the independent heating (similar to that at the exhaust pipe of the engine).
After starting (flame formation), the heater plug functions as the flame monitor.
The start procedure is repeated automatically if no flame is formed or the flame goes out during the start procedure. The fuel feed is stopped if again no flame is formed. The auxiliary heating system is switched off (entry in fault code memory).
Auxiliary heating operation
The auxiliary heating runs in full load mode after starting.
When the temperature in the independent heating circuit reaches the following value, the independent heating goes into part-load operation.
Changeover to part-load range at:
- E70
Petrol/gasoline engine: 80 °C
Diesel engine: 82 °C
- E90, E91, E92, E93
Petrol/gasoline engine and diesel engine: 77 °C
In part-load operation the temperature can rise to the following value. This is followed by a control pause.
Changeover to control pause at:
- E70
Petrol/gasoline engine: 88 °C
Diesel engine: 90 °C
> - E90, E91, E92, E93
Petrol/gasoline engine and diesel engine: 83 °C
The independent heating switches back to part-load operation if the temperature drops below the following value during the control pause.
Start from control pause at:
- E70
Petrol/gasoline engine: 70 °C
Diesel engine: 75 °C
- E90, E91, E92, E93
Petrol/gasoline engine and diesel engine: 65 °C
If the temperature rises again to the following temperature value, the independent heating switches again to control pause.
Changeover to control pause at:
- E70
Petrol/gasoline engine: 88 °C
Diesel engine: 90 °C
- E90, E91, E92, E93
Petrol/gasoline engine and diesel engine: 83 °C
If the temperature in the heating circuit drops again due to increased heating requirement during part-load operation, the independent heating control unit switches to full-load operation at the following temperature.
Return to full-load operation:
- E70
Petrol/gasoline engine: 65 °C
Diesel engine: 70 °C
- E90, E91, E92, E93
Petrol/gasoline engine and diesel engine: 60 °C
From terminal R independent heating operation also depends on the desired temperature value set at the IHKA controls.
Pseudo auxiliary heating mode with engine running
When the independent heating is running, pseudo auxiliary heating mode is started when the engine is started. When pseudo auxiliary heating mode is activated, the independent heater indicator lamp goes out. (The indicator lamp shows a flashing symbol in the display of the IHKA control panel.) The independent heating runs on.
The metering pump can be heard when it is operation (ticking noise).
If the engine temperature is greater than or equal to the temperature of the independent heating circuit, the system will change from pseudo auxiliary heating mode to normal heating mode. Auxiliary heating is deactivated.
Only the auxiliary heating circuit is used in pseudo-auxiliary heating mode.
Low-voltage cutout (via DME/DDE)
The battery's charge level is constantly monitored by the intelligent battery sensor throughout the independent heating operation. If the necessary charge level is not maintained, the IHKA control unit will deactivate the independent heating operation.
Overtemperature protection
The overtemperature protection facility responds at a temperature of approx. 145 °C. Auxiliary heating shuts down and locks.
Switch-off
The IHKA control unit switches off auxiliary heating after the set heating time has elapsed (30 minutes).
Auxiliary heating is switched off manually via the Telestart transmitter or with the aid of the controller in the CID. The heating blower is also switched off.
If auxiliary heating is not switched off by the IHKA control unit, the SHZH control unit automatically switches off auxiliary heating mode after an additional time of 10 minutes (entry in fault code memory).
The afterrunning period starts after auxiliary heating has been switched off. The auxiliary water pump (E90, E91, E92, E93) or circulating pump (E70) and the combustion-air fan continue to run in order to cool the independent heating.
The afterrunning time depends on whether auxiliary heating is switched off in full load mode, partial load mode or in the control pause.
When the run-on time has finished, the auxiliary water pump or circulating pump and combustion-air fan are automatically switched off.
Preconditions for activation
Preconditions for switching on auxiliary heating mode:
- Outside temperature below 15 °C
(Only in connection with programming with timer or Telestart. Direct operation is possible at any outside temperature but not while driving.)
- E70
Fuel reserve (9 litres) not reached, i.e. the fuel reserve telltale light does not light up
E90, E91, E92, E93
Sufficient fuel in the vehicles tank for a range of at least 50 km
- On-board supply voltage OK
Notes for service staff
Service staff should note the following points:
- General note:
- Diagnosis: ---
- Encoding/programming:
Subject to change.