Re: 89 740 Brake Light Problems
Mike F wrote:
> Charlie wrote:
>>My wife's '89 740 GL has lost both its main brake lights. The light over
>>the trunk (back window) still works. Bulbs are good, contacts clean. No
>>voltage at the rear connectors when the brake pedal is pressed & the
>>back glass light is lit.
>>The owner's manual says that fuse #4 powers the brake lights, & pulling
>>it kills the back glass light.
>>Other posts talk about 'integrity relays' & repair of same. Could this
>>be my problem, & if so, where are they on the 740? I've followed the
>>bundle from the left tail light assy up to the seat back without finding
> The bulb failure relay is the cylindrical relay in the central
> electrical unit, just toward the front of the car from the fuses. The
> terminal numbers for the brake lights are 54 (in from brake switch), and
> 54L and 54R outputs to the brake lights.
And like the other relays, you can pop the cover open and you'll find
circuit boards inside, look carefully for cracks in the soldering, it's
the only failure I've ever seen on those.