Shut-Off Standby Current Violation

Shut-Off Standby Current Violation

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 vehicle voltage by means of a bi-stable 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 bi-stable relay (depending on variant). In the event of a standby current violation, the bi-stable relay cuts off certain consumer units from the on-board supply voltage. The switched terminal of the bi-stable relay is called the closed-circuit current cutoff relay.The closed-circuit current cutoff relay stands for a terminal 30 that is switched (g) in the event of a fault (f).

Bistable relay (depending on variant)
For cutoff in the event of a standby current violation, there is a bi-stable relay. The bi-stable relay is arranged on the printed circuit board of the power distribution box (hidden by the housing of the power 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 standby current violation, this relay is activated to interrupt the voltage supply of the fuses mentioned.
The bi-stable 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).

Variant without bi-stable relay
The bi-stable 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.

Activation of bi-stable relay
The bi-stable relay is on the power 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 power distribution box and JBE).
The relay coils are supplied on the power 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.

Conditions required for switch-off, closed circuit current cutoff relay (fault)
In the event of a fault, the bi-stable relay is activated by the JBE in such a way that the voltage supply of the closed-circuit current cutoff relay is interrupted.The closed-circuit current cutoff relay is switched off if any of the following conditions occurs:
- With terminal R off, the JBE counts more than 30 wake-ups at terminal R.
- After 30 minutes of terminal R off, the JBE detects control units that are preventing the vehicle from entering the sleep mode.
- With terminal R off, the DME/DDE detects via the IBS that the startability limit has been reached (battery capacity is just enough to start the vehicle).

If the closed-circuit current cutoff relay is switched off due to a standby current violation, a fault 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 standby current violation. In all cases, the closed-circuit current cutoff relay is switched off. If the standby current violation is caused by a control unit that is not supplied by the standby current cutoff relay, the standby current violation remains even after cutoff.

Closed-circuit current cutoff relay switch-on conditions
A switch-on condition always has priority over a switch-off condition. Under the following conditions, the closed circuit current cutoff relay is switched on again via the bi-stable relay.
- Vehicle is unlocked
- Terminal change from terminal R off to terminal R or terminal 15
- Change in a status of door, bonnet or tailgate

The switching-on process is only run if the relay was previously switched off.
After every power interruption of the JBE, the bi-stable relay is activated in such a way that the contact is closed. In the normal case, the closed-circuit current cutoff relay is always switched on.With terminal R or terminal 15, the closed-circuit current cutoff relay is always switched on.