Antitheft Alarm System

Junction Box Electronics

The junction box plays a central role in the vehicle. In the junction box, the distribution box and junction box electronics form a unit. The junction box electronics is no longer the central gateway in the vehicle.

Brief description of components
The junction box consists of the distribution box and the junction box electronics.

JBE: Junction Box Electronics
The junction box electronics unit combines numerous functions in a single control module. The junction box electronics unit is connected via 4 plug connections.

A 54-pin connector is for the connection to the dashboard. Two other connectors are for the connection to the main wiring harness. These are 54-pin and 47-pin connectors. A 23-pin internal plug-in connection connects the junction box electronics directly to the distribution box.

Distribution box
The fuses and various plug-in relays are located in the junction box distribution box. Depending on the vehicle equipment, the boards of the distribution box are fitted with different relays. There is an opening in the lower part of the junction box. The junction box electronics are connected to the distribution box through this opening.

System functions
Numerous functions are provided in the junction box electronics (JBE). The junction box electronics perform a great many controlling tasks. Depending on the model series and equipment variant, the following functions can be controlled or signals detected by the junction box electronics:
- Power windows
- Wiper and washer system
- Central locking
- Climate control
- Seat heating
- Mirror heating and washer-nozzle heating
- bi-stable relay
- Functions for instrument cluster
- Roller sunblind for the rear window
- Roller sunblinds on the rear driver's side and rear passenger's side
- Roller cover for luggage compartment
- Interior rear-view mirror

Power windows
The footwell module (FRM) and the junction box electronics (JBE) control and monitor the power windows. The junction box electronics unit detects the following signals and makes them available to other bus subscribers:
- Power windows switch, passenger's door, front
- Power windows switch, passenger's door, rear
- Power windows switch, driver's door, rear
- Hall sensor, driver's door, rear
- Hall sensor, passenger's door, rear

The junction box electronics control the following actuators:
- Power window drive, passenger's door, rear
- Power window drive, driver's door, rear

Wiper and washer system
The junction box electronics unit detects the following signals and makes them available to other bus subscribers:
- Front reset contact
- Rear reset contact

The junction box electronics control the following actuators:
- Wiper module connected via LIN bus
- Wiper relay for rear window
- Washer pump relay for headlight-cleaning system

Central locking
The junction box electronics (JBE) are the executing control module for the central-locking system. The JBE handles activation of all the central-locking drives. The following control combinations are possible:
- Selective release
- Deadlock release
- Lock
- Unlocking and deadlock release
- Arrest

The luggage compartment lock is activated via its own final stage.

Climate control
The junction box electronics (JBE) unit detects the following signals and makes them available to other bus subscribers:
- Sensor for automatic air recirculation mode
- Coolant pressure sensor
- Rear compartment stratification adjuster

The junction box electronics control the following actuators:
- Additional coolant pump
- Control valve for air conditioning system or magnetic clutch
- Water valve (depending on engine)

Seat heating
For seat heating, a seat heating module or the higher-quality driver seat module can be installed. A seat module is always installed with seat memory. The junction box electronics (JBE) send a query to determine whether seat module is installed. If the junction box electronics do not receive confirmation, the junction box electronics handle activation of the seat heating. The junction box electronics generate a pulse-modulated signal. This signal activates the seat heating module.

If a seat module is fitted, the seat heating is activated directly by the seat module.

Mirror heating and washer-nozzle heating
The junction box electronics (JBE) control the following actuators:
- Basic version of the mirror heating
- Washer-nozzle heating

If mirror memory is installed, the footwell module (FRM) controls it via the LIN bus.

Bi-stable relay
The bi-stable relay is used to shut down terminal 30g-f if there is a closed-circuit current fault. The relay is only fitted for certain optional extras (e.g. CIC, TCU, ULF). If a bi-stable relay is fitted, an intelligent battery sensor is also fitted

Functions for instrument cluster
The junction box electronics unit detects the following signals for the instrument cluster:
- Fuel level sensor 1
- Fuel level sensor 2
- Coolant level
- Washer fluid level

Roller sunblind for rear window
The junction box electronics (JBE) actuate the drive for the roller sunblind.

Roller sunblinds on the rear driver's side and rear passenger's side
The roller sunblinds on the rear driver's side and rear passenger's side are each connected to the junction box electronics via a LIN bus.

Roller cover for luggage compartment
The junction box electronics actuate the drives for the roller cover in the luggage compartment.

Interior rear-view mirror
The junction box electronics activate the functions of the interior rearview mirror. The interior rearview mirror is connected to the junction box electronics via the LIN bus.

Line connection
As well as its electronic function, the junction box electronics unit (JBE) also have a connector function. Many of the cables in the 4 connectors connected to the junction box electronics are interconnected via the junction box electronics. The connections optimize the wiring harness. Here, the junction box electronics functions as a nodal point.

Relays of the junction box electronics
The junction box electronics (JBE) have internal and external relays. The excitation coils on all relays are permanently supplied with a positive cable. The positive power supply for the external relays is provided via the load circuit which is to be switched through. The positive power supply of the internal relay lies on the secured supply cable of the junction box electronics. All relays are controlled via the negative lead. All internal relays and the relay for wiper stage 1 and wiper stage 2 are located downstream of the fuse on the current circuit. All other external relays of the junction box electronics lie in the current circuit before the fuse.

Internal relays are:
- Relay for power window drive, rear
- Relay for the central-locking drive (except for luggage compartment lid)

The external relays are:
- Relay for drive, rear window wiper
- Relay for headlight-cleaning system
- Relay for heated rear window
- Bi-stable relay (deactivation of closed-circuit current fault)

No liability can be accepted for printing or other faults. Subject to changes of a technical nature