Reduction or shutdown of individual electrical consumer

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The shutdown of individual consumer units or reduction of the power consumption lowers the power consumption in critical situations. This prevents the battery from discharging. The power management controls the switch-off of individual consumers or reduction in the power consumption using requests (messages) to the relevant control units.

With the engine running

With the engine running, individual functions are divided into two classes:

Class A: A reduction in the power consumption or a shutdown of these consumers is only perceived by the driver to a limited extent or after a delay.
A shutdown of individual class A consumer units or reduction in the power consumption is only activated under the following 2 conditions:
- Battery charge state in the critical range
- High utilization of capacity of the alternator or reduced utilization of capacity of the alternator due to excess temperature.
Class B: A reduction in the power consumption or a switch-off of these functions is detected by the driver immediately. Shutdown of individual Class B electrical consumers or reduction of the power consumption is only activated under the following condition:
- Battery charge state in the critical range (close to the startability limit)

In the event of alternator fault

In the event of an electrical or mechanical fault on the alternator (reduced alternator availability), the power consumption of Class A and Class B electrical consumers is reduced by the allowable maximum amount in order to lower the power demand from the vehicle electrical system.
If alternator load is reduced due to excessive temperature (protective function), only the power consumption of Class A electrical consumers is reduced by the maximum amount allowable.

In the event of an engine shutdown (MSA)

To prevent excessive power consumption when the engine is switched off (MSA function), power consumption of Class A electrical consumers is reduced by the maximum amount allowable and that of Class B consumers by Reduction no. 1 (see table below).

With the engine off and the ignition switched on

With the engine off and the ignition switched on, consumers are not switched off or their power consumption is not reduced.

Class A electrical consumers

Under the conditions described, the following measures for class A consumers are executed in succession:

No.	Function	Operation	Control unit (depending on version)
1	Heated rear window	Pulsing	IHKA
1	Electronic ride height control	Delayed compressor activation	EHC
2	Rear seat heater	Stage 2	Rear seat modules or JBE
2	Electric auxiliary heater, rear	75 %	FKA
3	Seat heating, front	Stage 2	Front seat module or JBE
3	Rear seat heater	50 %	Rear seat modules or JBE
4	Electric auxiliary heater, rear	50 %	FKA
4	Heated windscreen, right	Off	SEC
5	Seat heating, front	50 %	Front seat module or JBE
	Rear seat heater	Level 1	Rear seat modules or JBE
	Heated windscreen, left	Off	SEC
6	Electric auxiliary heater, rear	25 %	FKA
	Steering wheel heating	50 %	SZL
	Heated side window, front right	Off	SEC
7	Electric auxiliary heater, rear	Off	FKA
	Mirror heating	Off	JBE or FRM
	Washer jet heating	Off	JBE
	Heated side window, front left	Off	SEC
8	Steering wheel heating	Off	SZL
9	Seat heating, front	Off	Front seat module or JBE
9	Rear seat heater	Off	Rear seat modules or JBE
10	Heated rear window	Off	IHKA
10	Top HiFi system or BMW Individual High End audio system	Max. 30 A power consumption after engine start	AMPT

Class B electrical consumers

Under the conditions described, the following measures for class B consumers are executed in succession:

No.	Function	Operation	Control unit (depending on version)
1	Top HiFi system or BMW Individual High End audio system	Max. 30 A power consumption	AMPT
	Heater blower, front and rear	75 %	IHKA, HKA or FKA
	Restriction of use of the electric fan by the air conditioning	66 %	IHKA (only in combination with engine N74)
2	Heater blower, front and rear	50 %	IHKA, HKA or FKA
2	Restriction of use of the electric fan by the air conditioning	50 %	IHKA (only in combination with engine N74)
3	Heater blower, front and rear	25 %	IHKA, HKA or FKA

When the battery charge state moves out of the critical range, the functions become 100 % available again.

IMPORTANT: When the shutdown of individual consumer units or the reduction of power consumption is activated, the displays remains active (LEDs remain lit).