Brake switch/light stuck on

[arbik]

Hi everyone,

so last night, I got pulled over by the law for a lack of tail light.
I had no idea of course.
I went home, looked at the bulb and both elements were burned/melted. Looked like overheating.
I replaced the bulb and I found that the brake light comes on and stays on, when you use the brake lever.
Looks like the brake lever micro switch is sticking, and not releasing.

I'm gonna look into it tonight. Any thoughts/ideas on this?

Thanks,

-arbi

[baltm604]

check the little switch down by the rear brake lever.

Bill

[priapismic]

Front brake or rear?

Happened to me once on the rear. There is an adjusting bolt on the rear brake arm, aft of the pedal, that controls how much pressure is maintained on the switch. It's one of those circuits that remains open until the brake is engaged, which removes pressure off the switch, breaks the circuit, and turns the brake light on. Couple of turns on that bolt applied a slight bit more pressure on the switch, and the problem was solved, never to occur again. If it's the rear brake, check this bolt first.

If it's the front brake, I agree about checking the switch. Sometimes they get a bit sticky from road grime, and maybe a bit of contact cleaner in there will free it up. There have been posts on this before, do a thread search.

[DG02]

A couple of years ago I had this very thing happen. A small tar-covered pebble had lodged itself in the rear brake switch, causing it to stick on. Undo a couple of bolts to get at the switch and you should find the cause.

I looked there first based on an earlier post on this board, seems it has happened to others before.

[Trapper]

I had a similar thing happen not long ago. A mate who was following me down some twisties couldn't work out how I was managing to ride so long without braking. Turns out my brake light was constantly lit, and he thought it was just my tail light.

It took a while ('cause I'm slow) to work out that the front brake lever was fouling (ever so slightly) against my right GS handguard. It had twisted just enough to stop the lever fully releasing. It wasn't at all obvious, and I'd ridden a couple of hundred miles with it like that, and had missed it a couple of times despite looking closely at it.

May be something completely different - but you never know.

Hope it helps

[arbik]

The Front brake switch is what was binding. Here is what was wrong.

It was the microswitch. BMW emblem on it and everything.
Normally closed unit, so when you sqeeze the brake lever, it lifts the metal lever and lets the switch go to its normally closed state. releasing the brake lever pushes on the little lever on the switch and opens the connection inside.
the pivot point is made of plastic. The lever is made of metal.
Over time, the plastic wears off, and creates play. I just bent the metal lever a little bit and it seems to have done the trick. A real fix would be to find a replacement microswitch that is exactly the same. It gets screwed with a single screw and an index pin. So I doubt a non exact substitution will work.
BMW of course, sell sthe whole assy as a unit.


-arbi

[R4R&R]

This happened to my bike within the first six months that I owned it. It was the switch in the front brake handle. I took it to the dealer since the servo brakes never activated - it turned out the brakes lights were always on. They made an adjustment and it hasn't given me a problem for 40,000 miles.