R80GS Basic brake light question

[Dave Ross]

#1867

I have just replaced the taillight bulb and found that the front brake does not activate the brake light, only the rear brake does that. Any ideas where to look for the fault first? I've lubricated the front switch, but that didn't do it. Cheers,Alex

[Murray]

#6658

I have just replaced the taillight bulb and found that the front brake does not activate the brake light, only the rear brake does that. Any ideas where to look for the fault first? I've lubricated the front switch, but that didn't do it. Cheers,Alex

Alex, it's probably a problem with the actuator switch. As I recall there were BMW Service Information Bulletins that were issued in the late 80s regarding the front and rear brake light switches on K series and airheads of the day. The bulletins advised a modification to be done to the front brake lever; and a cap added to the rear brake lever actuating bolt head.....excepting, I think, the R80GS REAR, for which it did not apply exactly the same way. Basically, the front brake lever itself was not contacting the switch actuating pin properly, the pins bent, and failed.  The switch was updated, and one was to also modify the front brake lever.  You needed to remove the front brake lever, a very easy job, and file down the lever in one place slightly so it did not 'catch' the brake switch pin.SO....how to tell if your bike was fixed? Inspect the actuating pin of the front brake light switch. WHITE pins are the bad ones. Black or dark Gray are OK.  Some R80G/S bikes used a different front switch....and if the switch wires can be unplugged, then it is not one of the bad recalled ones.    However, all should be inspected for condition of the pins, lever, etc. In any case, the small ridge on the front lever is to be sanded or filed off.It is not easy to describe, without a drawing, what is modified on the front brake lever....but, if the lever is removed, you will see the area around the pivot has some notches/cutouts.  There may be a very small very tiny notch on the outer curve, and it is the one to be smoothed.  If you put the lever into place without the pin-bolt holding it, you will rather easily see what portion contacts the switch pin, and why, if you have a lever needing modification, it should be done.Of course, you may just have a pinched wire somewhere that is earthing on the frame.Hope that helps.Garry

[Dave Ross]

#6659

Thanks for the detailed reply Garry. I'll have another look at the switch, from memory the pin was blackish. With the switch removed I would have expected the brakelight to come on, which it didn't. So this seems to point to a damaged wire somewhere along the line. Can the the switch be disassembled?  I did notice the the wire did not swivel in the housing as I removed the switch, so I am concerned that I may have wrung its neck.

[Murray]

#6660

Thanks for the detailed reply Garry. I'll have another look at the switch, from memory the pin was blackish. With the switch removed I would have expected the brakelight to come on, which it didn't. So this seems to point to a damaged wire somewhere along the line. Can the the switch be disassembled?  I did notice the the wire did not swivel in the housing as I removed the switch, so I am concerned that I may have wrung its neck.

Bypass the switch (a paper clip will do the trick);- if the bulb lights up get a new switch, you can't disassemble and it's not expensive to replace.- if the bulb doesn't light up the problem lies elsewhere

[Dave Ross]

#6661

I've had another play with the switch. By fiddling with the switch and the wires attached to it I could make it work. However, the switch appeared to be heating up, which has me worried. I am tempted to remove the insultation around the switch to get a better look. Is there a plug on the other end of the the wire? I couldn't see one, even after removing the tank.

[Dave Ross]

#6662

Ok, it must be the switch. Neil has one in stock, so I'll no for sure soon enough. Thanks for your help.Cheers,Alex

[Murray]

#6663

I've had another play with the switch. By fiddling with the switch and the wires attached to it I could make it work. However, the switch appeared to be heating up, which has me worried. I am tempted to remove the insultation around the switch to get a better look. Is there a plug on the other end of the the wire? I couldn't see one, even after removing the tank.

Get a new switch!!

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