Consumer Shut Off Function Sequence
- If the alternator can no longer provide the required electrical power, the load on the on-board electrical system is reduced by cutting back comfort functions. This serves to avoid any significantly negative charge balance for the battery. The mobility of the vehicle is maintained. The comfort functions are reactivated when the required electrical power to stabilize the on-board electrical system voltage is available again.
- The function for cutting back comfort functions is activated when the on-board electrical system voltage drops below 12.2 V. The first consumer's power consumption is reduced at 20 seconds after engine start. If the cutback conditions remain unchanged, the power consumption of one further consumer is reduced every second afterward.NOTE: The front seat belt pre-tensioner LH and front seat belt pre-tensioner RH have very high starting and operating currents. The power consumption of some high power consumers is therefore reduced or the consumers shut off altogether for approximately 2 seconds when the front seat belt pre-tensioner are triggered for reducing the load on the on-board electrical system.
- BCM transmits the request for power reduction or shut off over the interior CAN to the corresponding control units.
- The shut off sequence is shown in the following table.
Shut off step
Consumers with reduced or no power
Responsible control unit
Maximum current
1
PTC heater heating level 6 (Passenger side)
A/C auto amp.
18.5 A
2
PTC heater heating level 5 (Driver side)
A/C auto amp.
18.5 A
3
PTC heater heating level 4 (Passenger side)
A/C auto amp.
18.5 A
4
PTC heater heating level 3 (Driver side)
A/C auto amp.
18.5 A
5
PTC heater heating level 2 (Passenger side)
A/C auto amp.
18.5 A
6
PTC heater heating level 1 (Driver side)
A/C auto amp.
18.5 A
7
Heated seat level 3
- Driver seat control unit
- Passenger seat control unit
13.2 A
8
Heated seat level 2
- Driver seat control unit
- Passenger seat control unit
13.2 A
9
Door mirror defogger
- Left front door control unit
- Right front door control unit
3.5 A
10
Rear window defogger
A/C auto amp.
30.0 A
11
Front blower P=50%
A/C auto amp.
16.0 A
12
Radiator fan P=50%
A/C auto amp.
31.0 A
13
Power sockets
BCM
6.0 - 8.0 A
14
Heated seat level 1
- Driver seat control unit
- Passenger seat control unit
3.3 A
- When the on-board electrical system voltage is stabilized to a value above 12.2 V, the comfort functions are switched on again in reverse order with a delay time of 1 second each.