General functional description of power supply, see BMW Technology: TIS -> Document -> SI Technology -> Enter SBT number
SBT number: -> 61 03 04092
In the 5 Series and 6 Series as of E60, there is the micro-power module (MPM). In the event of a fault, the MPM disconnects some control units from the on-board supply voltage by means of a bistable relay. Above all MOST control units are supplied from this terminal.
In the 1 Series and 3 Series as of E87, there is also a bistable relay (depending on variant). In the event of a closed-circuit current fault, the bistable relay cuts off certain consumer units from the on-board supply voltage.
The switched terminal of the bistable relay is called terminal 30g-f.
Terminal 30g-f stands for a terminal 30 that is switched (g) in the event of a fault (f).
For cutoff in the event of a closed-circuit current, there is a bistable relay. The bistable relay is arranged on the board of the distribution box (hidden by the body of the distribution box).
The bi-stable relay activates terminal 30 on the fuses F17 and F40 (up to model year 03/2005), or F17 and F31 (as of model year 09/2005). In the event of a closed-circuit current, this relay is activated to interrupt the power supply of the fuses mentioned.
The bistable relay has two relay coils that open or close the relay contact as the case may be on activation. The relay persists in the last activated position (contact open or closed).
The bistable relay is only present with certain optional extras. In vehicles without a bi-stable relay, the fuses F17 and F40 (up to model year 03/2005) or F17 and F31 (as of model year 09/2005) are connected by a bridge to terminal 30g.
The bistable relay is on the distribution box and is activated by the junction box electronics (JBE). The activation lines run via the internal connector X04010 of the junction box (consisting of distribution box and JBE).
The relay coils are supplied on the distribution box directly via terminal 30.
The JBE switches the negative lead onto the relevant relay coil for a short time to open or close the contact.
In the event of a fault, the bistable relay is activated by the JBE in such a way that the power supply of terminal 30g-f is interrupted.
Terminal 30g-f is switched off if any of the following conditions occurs:
If terminal 30g-f is switched off due to a closed-circuit current fault, a fault code memory entry is stored in the JBE.
When terminal 30g_f is switched off, it is not taken into account which control unit is responsible for the closed-circuit current fault. In all cases, terminal 30g-f is switched off.
If the closed-circuit current fault is caused by a control unit that is not supplied by terminal 30g-f, the closed-circuit current fault remains even after cutoff.
A switch-on condition always has priority over a switch-off condition. Under the following conditions, terminal 30g-f is switched on again via the bistable relay.
The switching on is only run if the relay was previously switched off.
After every power interruption of the JBE, the bistable relay is activated in such a way that the contact is closed.
In the normal case, terminal 30g-f is always switched on.
With terminal R or terminal 15, terminal 30g-f is always switched on.