As I was resoldering the relays on my 1990 745, I pulled one that puzzled me.

This relay is a black one with three prongs, it sits right in the middle of the relay board behind the lock relay. It's marked SAE J590 and SAE J945 in white letters on the side.Top is marked like this:

TBB76 DOT
4DB 003750-31
2(4)x21W/32cp-12V

First, I noticed the middle prong was discolored by head or electrical arcing. When I cracked it open, the trace running along the right side of the circuit board looked odd. I can't quite tell if the metal is gone and only the lacquer is there, or if it is lacquered over.

What is this relay for? Should that trace look like that? If it is burned off, I could solder a thin wire strand in it's place, but I have to wonder what made it burn.

Probably the relay toasted after the contacts became worn/pitted and resistive.
It's time to get a NEW relay.

Bill

Here is the map for relay identification: cut and paste if not highlited
http://www.swedishbricks.net/700900FAQ/Electrical-CircuitsRelays1.html#Relay%20Locations

There is a slight problem with this picture. The drawing doesn't match the photo, it shows empty sockets in the spots that are filled in the photo.

Still, it tells me the thing I'm asking about is either the flasher or the main light relay. I suppose if I pulled it, I would know what stops working.