Voltage Supply, Junction Box Electronics (JBE)
Voltage Supply, Junction Box Electronics (JBE)
JBE minimum function:
The junction box electronics (JBE) are inserted in the bottom of the power distribution box (SV). The JBE (A04010a) and power distribution box together are referred to as the junction box (A04010).As soon as the junction box electronics are able to communicate with the diagnosis system, the following voltage supply is present:
- Diagnostic cable via connector X14271
- Earth connection via connector X14270
- Voltage supply (unfused) from power distribution box via the internal connector X04010.The processor and CAN bus communication gateway function (between PT CAN and K CAN) of the JBE are supplied across this cable.
- Voltage supply (fused via F63) from the power distribution box via the internal connector X04010.All other functions of the JBE are supplied across this cable. Exceptions are the drives switched by the JBE via relays.
Relays of the JBE (internal and external):
Functions of internal relay (in JBE):
- Electric motors for rear power windows (F62/F64)
- Electric motors for central locking system (F56/F57), except tailgate and rear window
Functions of external relay (on power distribution box):
- Electric motor for rear wiper
- Electric motor for wiper stage 1 and wiper stage 2
- Pump for headlight cleaning system
- Activation of heated rear window
- Bi-stable relay (cutoff with standby current faults)
All the relay coils of the relays of the JBE (internal and external) are permanently supplied with a positive wire.The positive power supply of the relay coils of the external relay comes from the through-switching load line.The positive power supply of the relay coils of the internal relay comes from the fused voltage supply line of the JBE (F63).All relays of the JBE (internal and external) are controlled via the negative lead.
All the internal relays of the JBE and the relays for wiper stage 1 and wiper stage 2 are located in the current path behind the fuse. All other external relays of the JBE are located in the current path in front of the fuse (relay sound also in the event of a faulty fuse).
Bus connections:
The JBE is connected to the PT CAN and the K-CAN. The JBE is the gateway for these buses. Communication between the diagnosis system and JBE is independent of these buses, as the diagnostic cable is connected directly on the JBE.
Examples of functions that require both buses and the gateway: DSC button, volume control buttons on the multifunction steering wheel (additional F-CAN)
Examples of functions that require the K-CAN:Power windows in door on the passenger's side via switch in door on the passenger's side, central locking button, parking brake switch
Examples of functions that require the PT-CAN:Wiper functions (additional F-CAN), windscreen washer pumps (additional F-CAN)
Line connections in the JBE:
Alongside its electronic function, the JBE also has a connecting function for many cables of the 4 connectors connected to the JBE:
- Internal connector between JBE and power distribution box:X04010
- Connector in direction of travel:X14270
- Connector in opposite direction of travel: X14271 and X14272
The connections only serve to optimise the wring harness. The JBE only functions here as a line. In detail, the following connections are involved:
- 4 voltage supplies (F58, F59, F60, F61)
- One for activation of the horn relay
- 2 for the outside temperature sensor
- 2 for F-CAN
- One for the hotel position switch
- 2 for SMG rocker switch
- 2 for blower (diagnostic signal/ PWM control signal)
- One for the electric auxiliary heater (PWM control signal)
- One for the central locking button
- 21 earth outputs connected with earth input on X14270
- 5 K-CAN connections CAN Low (internally connected on one line)
- 5 K-CAN connections CAN High (internally connected on one line)
Functions of the JBE:
The JBE performs the following functions:
- Gateway to diagnostic cable
- Gateway between PT CAN and K-CAN
- Activation of the bi-stable relay for cutoff in the case of standby current violation (same as MPM on E60). The relay is only fitted for certain optional equipment (e.g. CCC, M ASK, TCU, ULF). If a bi-stable relay is fitted, an IBS is also fitted.
- Power window functions (sensor system (depending on variant): Hall effect sensors - 2 for passenger's side at rear and 2 for driver's side at rear; switches: door on the passenger's side, passenger's side at rear, driver's side at rear; drives: passenger's side rear, driver's side rear)
- Windscreen washers (contacts: reset contact at front, reset contact at rear; activation: relay for wiper stage 1 and wiper stage 2, rear window wiper relay)
- Central locking functions (activation of all drives)
- Air-conditioning functions (sensor system (depending on variant): Automatic air recirculation control sensor, refrigerant pressure sensor, rear stratification control; activation (depending on variant: auxiliary water pump, water valve, control valve in the air-conditioning compressor)
- Functions for instrument panel (sensor system: fuel level sensor 1, fuel level sensor 2, coolant level, washer fluid level, parking brake switch)
- DSC button (switch: DSC button)
- Mirror/Washer jet heating (activation: Washer jet heating and basic version of the mirror heating, together via an internal electronic switch). Activation of mirror heating not if LIN mirrors are fitted. Then activation via LIN from FRM.
- Seat heating (activation: PWM signal for basic version of seat heating, driver's side and front passengers side). Not if seat module is fitted on corresponding side. Then activation via seat module of corresponding side.
- Heated rear window (activation: relay for heated rear window)
- Headlight-cleaning system (activation: relay for headlight cleaning system)
- Roller sunblind (activation: electric motor for roller sunblind)