Brief description
The closed-circuit current cutoff relay is only installed with some optional equipment, e.g. when the Car Communication Computer (CCC) has been ordered. The closed-circuit current cutoff relay switches off in the event of faults on the connected consumer units.
The closed-circuit current cutoff relay is a bi-stable relay and is fitted on the printed circuit board of the power distribution box. The relay is activated by the junction box electronics (JBE). The bi-stable relay has two relay coils that open or close the relay contact on activation. The relay persists in the last activated position (contact open or closed).
Switch-off conditions of the closed-circuit current cutoff relay (failure) The bi-stable relay is activated by the JBE in the event of a fault in such a way that the voltage supply for the closed-circuit current cutoff relay is under briefly or permanently. The closed-circuit current cutoff relay is controlled under one of the following preconditions:
- At < terminal R Off > and after shutdown of terminal 30g, the JBE counted more than 20 wakings (resets). After the reset of the closed-circuit current cutoff relay the JBE counts another 5 wakings, the closed-circuit current cutoff relay is switched off permanently.
- With < terminal R Off > and 10 min. after shutdown of terminal 30g, the JBE registered control units that prevent the vehicle from sleeping. If the vehicle sleeping is prevented for another 10 minutes after the reset of the standby current cutoff relay, the closed-circuit current cutoff relay is switched off permanently.
- With < terminal R Off >, the power management determined by means of IBS that the battery charge state is close to the startability limit.
When closed-circuit current cutoff relay is reset or switched off, it is not taken into account which control unit is responsible for the fault. In all cases involving faults, the closed-circuit current cutoff relay is switched off. If the fault is caused by a control unit that is not supplied by the closed-circuit current cutoff relay, the fault remains even after cutoff.
Conditions required for switch-on of closed-circuit current cutoff relay A condition for switch-on always has priority over a switch-off condition. Under the following conditions, 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 ON > or < terminal 15 ON >
- Change in a status of door contact, bonnet or tailgate
In the normal case, the closed-circuit current cutoff relay is always switched on. With < terminal R ON > or < terminal 15 ON >, the closed-circuit current cutoff relay is always switched on.