The independent park heating offers the customer a system for preprogrammable heating of the vehicle interior.
The independent heating system is activated via the multi-information display, on-board monitor or telestart (independent heating system remote control). The independent heating system additionally includes the following functions:
The independent park heater (Webasto) features its own control unit. The independent heating system is activated via a "wake up" wire from the heater operating unit. The independent park heater sends a feedback signal via the independent heating status line to the heater operating unit indicating whether the independent heater has switched on.
During operation of the independent heating system, the coolant temperature sensor of the DME (digital engine electronics) has to be prevented from be heated up by the independent heating system has to be prevented. To prevent the DME receiving a false reading of the engine temperature, the coolant circuit is isolated by a cut-off valve in the vicinity of the coolant temperature sensor.
Shut-off valve
Installation of a shut-off valve depends on the engine variant and can be read out in the DIS via "Independent park heating - Service functions - Read coded data".
The radio remote control function makes it possible to start the independent heating from a distance of up to 400 m.
Telestart
The range may be restricted from closed rooms. When operating, the hand-held transmitter should be held with the antenna pointing upward.
The start procedure is initiated by pressing the left-hand rocker switch. The LED at the top edge of the hand-held transmitter indicates that the start signal has been sent (flashes max. 30 minutes = running time of independent park heating system).
Initialisation of hand-held transmitter for telestart:
If a new telestart receiver is installed, the two hand-held transmitters must be re-initialised.
Undervoltage cutout
Fundamental prerequisite for the operation of the independent heating system is a sufficient battery charge. The undervoltage threshold depends on the outside temperature and is compared with the terminal 30 voltage applied at the operating unit. If this voltage at the operating unit drops below the calculated value, operation of the independent heater is ended.
The function, independent heating, can be activated via the on-board monitor or MID when the ignition key is turned to position 1, or by telestart when the ignition key is in position 0. Various settings are possible dependent on the ignition lock position.
Statuses in ignition lock position 1:
Statuses in ignition lock position 0:
Signal sequence for independent park heating operation when switched on via MID or on-board monitor with/without preprogramming:
During preprogramming, the independent heating telegram is triggered at a set moment in the IKE via MID or on-board monitor by pressing the button on the relevant operating unit in ignition lock position 1. The "independent heater ON" request is then transferred via the K-bus to the heating operating unit (IHKA, IHKR or IHR control unit). The control unit emits a voltage signal to the "wake-up" wire, which forwards the signal via the telestart receiver to the independent heater unit (the voltage can be between approximately 6 V and 9 V, depending on the model in question. If a circuit is broken or a fault is present in the telestart receiver, this voltage can increase to the voltage of the vehicle electrical system). Now the independent heater will switch on and emit a voltage signal to the heater operating unit through the feedback wire. If the feedback signal is not recognized by the heater operating unit within the next 5 seconds, the switching on procedure is interrupted.
Obtaining status at the DIS:
Signal sequence for independent park heating when switched on via telestart:
The radio waves from the telestart transmitter are forwarded via the rear window to the block circuit in the C-pillar, where the HF signal is converted to a LF signal. This is then forwarded to the telestart receiver, which switches a voltage signal of approximately 5 to 8 volts to the independent heater. Now the independent heater will switch on and emit a voltage of about 12 volts through the feedback wire to the heater operating unit.
Obtaining status at the DIS:
Signal sequence for switching off independent park heating via MID or on-board monitor:
The command, independent heater OFF is transmitted via a telegram on the I-bus to the IKE and then via the K-bus to the heater operating unit (IHKA, IHKR or IHR control unit). The control unit diverts the voltage signal from the "wake-up" wire via the telestart receiver to the independent heater unit (if an undervoltage or a fault is present in the independent heating system, the signal is pulsed on the switch on wire). The independent heater now switches off and allows the voltage on the feedback line to the heater operating unit drop below 3 Volt.
Obtaining status at the DIS:
The cut-off valve is placed under current for a further 2 minutes during the rinsing phase and then switches off.