Brake Lights

I have an 89' 740 GL. I was wondering if anyone could tell me if there is a
relay that controls the brake lights, and if so where I could find it. The
problem that I am having is that only my 3rd brake light works (the one in the
rear window). The regular brake lights will not work. All other lights seem to
work fine and I have checked all the fuses and bulbs. If anyone has any advice
I would greatly appreciate it.

Thanks,
Charles

 

Sounds like either a bad ground or the bulb failure warning sensor.If you
get no power to the connector on the taillight then it is the sensor. It's
round, orange,and located behind the ash tray. Pull out the ash tray, pop
off the bezel around the lighter, remove the two screws there and take out
the pocket.Try to find some one who will let you borrow theirs to try before
you buy because they are expensive.

 

There isn't a relay, I've fixed a couple of these with the same problems
with the taillights by resoldering the circuit boards in the bulb failure
sensor, it's a red can near the relays.

 

If you change the bulb failure warning unit you should restore normal operation
of all three brake lights. The thing to change is the round can at left of third
row of relays in the relay tray. You could try to see if there is any corrosion
around the connections before discarding the old unit just in case this is the
cause of the trouble.

Cheers, Peter.
..


: I have an 89' 740 GL. I was wondering if anyone could tell me if there is a
: relay that controls the brake lights, and if so where I could find it. The
: problem that I am having is that only my 3rd brake light works (the one in the
: rear window). The regular brake lights will not work. All other lights seem to
: work fine and I have checked all the fuses and bulbs. If anyone has any advice
: I would greatly appreciate it.
:
: Thanks,
: Charles