In the center console there are a few relay sockets.
The right one is for an optional secondary alarm system.
The center one is for the optional chime relay, facilitating seat-belt warning, door-open+Key-in-ignition, door-open+Key-out-of-ignition+marker-lights-on, Door-open+Key-out-of-ignition+parking-lights-on. It has a interconnect generic plug 928.615.211.00 if the chime relay is not installed.
The left one is the additional alarm flasher relay, 928.637.160.00, also called "Anti Theft Relay", that is optional and makes the front and rear fog lights flash in alarm situation (and enabling the alarm?
This chime relay is mentioned in many schematics as optional timing relay, but the bridge is only mentioned in the 1990 schematic. Strange...
It seems the bridge interconnects the seatbelt warning when the relay is not existing.