For Bavaria owners who want to mount fog lights but who are intimidated by the lamp manufacturer's wiring diagrams and/or the thought of cutting holes in their dash, most of the work has already been done for you at the factory.
Before you actually do any work, check that all elements referred to in this article are the same on your car. That square plastic socket covered with tape next to the high beam and horn relays (those two little round aluminum cans mounted next to the battery) is for a fog light relay. The relay acts as a remote switch, handling the relatively heavy load of the halogen bulbs more efficiently and with a shorter wiring run than if the whole load went through your dash switch.
When you remove the tape you will find three metal connectors in the socket. Remove one of the other relays, look at the numbered pins, and you will see that the fog light relay socket has connections for pins 30, 85 and 86 already wired in place. Number 30 is power ( + ), 85 and 86 operate the relay, 87 (the missing one) is for load (your lights). Mount your lights and run the wire back to the relay socket. Crimp the end of the wire into a flat slide-on female connector and insert into the empty spot in the socket from below. Buy a relay from your dealer BMW #61311350315) and plug it in. You may have to push the slide-on connector onto the relay pin itself if you can't find the type that lock onto the socket. If you want to use a non-BMW relay (much cheaper), make sure the pin arrangement is the same or you won't be able to plug it in.
Remove the four screws holding the lower panel with the flasher and rear window defroster switches. At the upper left corner of this panel there is a hole pre-cut with the cut-out circle cemented back in place. Follow the outline of the circle and cut through the vinyl. Press out the cemented piece. Ask your dealer for the green accessory switch (BMW # 61311353589) and mount it in the hole. Look under the dash to the left of the steering column for a round plastic connector hanging loose on four wires. Plug it onto the switch, reassemble the panel, and the job is done.
The switch installation matches your other dash switches, except in color (illuminated green), and looks "factory." The main light switch must be on either park or headlights to operate the fog lamps; they cut off automatically if you turn on high beams or operate the headlight flasher. One caution: if you turn off the ignition switch and leave the headlight switch on (for parking lights) with the fog light switch on, the load-shedding relay that cuts off headlights, rear window defroster, air conditioner, etc., will not cut off the fog lights. Also, see Jon Barletta's article, "Bavaria Rear Fog Lights" in the October/November 1974 Roundel,
Author: Charles Schulze
Bailey Drive, North Branford, CT 06471