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Re: "brake light out" light on even though it work (archive)
[ Follow Ups ] [ 5-series (E28) Message Board ] [ Msg. Board FAQ ]
Posted by Clyde on October 29, 2000 at 12:53:55:

In Reply to: "brake light out" light on even though it works! posted by Dan Latta on October 29, 2000 at 11:20:26:


My '87 535is has the overhead "brake light" warning on although all the lights at the rear are operating perfectly. I have replaced the rear (all) bulbs with the silver based ones (no copper based) as well as replaced the main gaskets which were in poor shape. I've checked to see if there has been any water leak and there is not. Humidity is not a factor here in "sunny" Los Angeles.

When I start the car the all familiar "check" light is flashing on the dash and after pushing "check" above the brake light remains on. Once I've pressed the overhead check button the dash "check" does not flash until the next time I've started the car.
The car had some rear end damage at some point in it's life but all the repairs were done extremely well.

This just in-I've discovered the reverse lights do not work although the bulbs are fine.

Any ideas of a direction to go in to get the dang "check" light to stop flashing at me everytime I start the car? (as well as getting the reverse lights to work!) Thanks as always to a superior board with many E28 enthusiasts smarter than me (not hard to do!).


I'll assume the window-mounted center brake light is also in good shape, and that you've bent the tabs on the bulb holders and scuffed the tinned contact areas on the taillight assemblies to assure a good electrical contact.

Try checking the brake light switch mounted on the brake pedal bracket (two pins on the switch): with an ohmmeter, it should read less than .5 ohms when "closed." If not, replace the switch. If it is okay, use an awl to slightly deform the sockets on the wiring harness, for a tighter fit -- that's what finally cured the problem for me. The sensor circuit is looking for any evidence of low overall current draw when the brake lights are applied. A high resistance in the switch or between the switch and the contacts has the same effect as a burned-out bulb.

The backup light is a separate issue, unrelated. You'll find lots of posts in the search engine about bad switches (they screw into the transmission).

Good luck.


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