K11 Owners Group

mnb · Posted: Tue Feb 19, 2008 2:44 am Post subject: Brake light stays on

Coming home from Death Valley today, a fellow rider pointed out that my brake light has a tendency to stay on.

When I got home, I put it on the center stand, put the kickstand up, ignition on and noticed:

if I apply both brakes, the warning light goes out.

application of either brake fails to cause a brighter illumination.

I tried each brake several times. I also shut the bike completely off and put the ignition back to "on" before trying the same tests. Kill switch was not in the kill position.

The rider had said that the brake light appeared to be stuck on, but went off after a while. After significant questioning, brake light off meant the tail light was, in fact, still on.

I'd thought from this that one of the brake light switches was bad, but I was unable to get the light to change at all.

If the brake light bulb was bad, the warning light wouldn't go off. So, assuming that test is correct, then the brake light IS staying on.

Any ideas?

Flying Duck · Posted: Tue Feb 19, 2008 3:25 am Post subject:

Are you looking at the brake light when you're testing the switches on the center stand? If you can't see it, back your bike up to a wall so you cen tell ifit's going on and off or not.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

BMGraeme · Posted: Tue Feb 19, 2008 5:41 am Post subject:

It's early days in your diagnosis of the problem but its quite commomn for the Front brake master cyclinder to get crud caught up in it preventing the piston from fully returning. This will leave the brake light on as the switch is deactivated by the piston. You can usually tell by manually returning the front brake lever all the way back by hand to see if the light goes off or not.

I find it's mostly water entry around the piston that leaves limescale deposits thats the culprit and give it a regular clean up.
_________________
1980 CB900FA
1994 K1100RS
2008 R1200GSA

mnb · Posted: Tue Feb 19, 2008 3:42 pm Post subject:

I did the tests at night, so I could see the change in the intensity of the glow from the rear light assembly.

I did push/pull on both the foot brake pedal and the front brake level. Neither had any effect. I'll take a look a the front brake lever today and see if it needs any cleaning.

Daniël V · Posted: Tue Feb 19, 2008 4:28 pm Post subject:

Flying Duck · Posted: Tue Feb 19, 2008 5:04 pm Post subject:

The BMW piston switches used for the front brake and clutch lever can build up crud inside them and get sticky. On the early K bikes, they used the same switch for the rear brake. Those were more prone to failure given how nasty and dirty the environment is down there. I"m pretty sure that's why they switched to the current rear brake switch in 86 or 87.

I've seen a lot of failed piston switches so I wouldn't be surprised if that were the cause.

FYI: The choke sensor (for the idiot light on 2 valve Ks) also used those piston swtiches on the throttlebodies. I imagine that on the initial design it was supposed to be a "universal" switch.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

gpzoduibh · Posted: Wed Feb 20, 2008 6:55 am Post subject:

Silly question but when youre sitting on and riding you may be dragging the pedal or if its set too sensitive you may be bringing on the brake light but not the brake with youre foot "hovering" over it ? Just a thought if everything else checks out ok ?
Regards
Bill Black
_________________
1995 Grinnall Scorpion III(1990 K100 16v motor)
2010 KTM 450 EXC
Moto Guzzi V50 powered hovercraft !
1989 K100RS (8V) special edition
1974 Yamaha DT360
1972 Sanglas 400 T
1980 Yamaha XS110-Watsonian Palma sidecar
1966 Bridgestone 175 dualtwin
1980 BMW R100RS
1979 Bultaco sherpa T 350
1979 Yamaha DT175MX
1990 Honda XR250R

mnb · Posted: Wed Feb 20, 2008 5:07 pm Post subject:

I'd checked the bike on the centerstand and I was off the bike, so riding the brake wasn't a possibility.

I just pulled the cover off the front brake lever to allow access to the switch. Surprisingly easy - 1 screw. I flipped the metal blade out and in and then operated the lever at least 20 times and the brake light worked every time. I didn't touch the rear until I verified the front, so I think it's the front switch that's sticking. It's working fine now.

I cleaned the surrounding areas with a tooth brush. I didn't have any electronic parts cleaner to use, though. I'm smart enough not to spray WD-40 on a part that needs electrical conductivity, though. Smile

As I expected, the advice I got here regarding what to check was spot on. You guys are great. I hope that I can be similarly helpful in the future.

On an entirely off-topic issue... I just got back from Death Valley and while I was visiting Rhyolite (the ghost town), I spotted a K100RS. The rider was from Marin. I noticed he was sporting a Wilbers shock and mentioned that under speed in corners I have a side to side wobble that is rather unsettling. He said his bike used to have that, but using the Wilbers solved that problem. Turns out he went to The Beemershop in Scotts Valley, which is my new shop of preference as well. He also upgraded the forks with Progressive springs. I was planning on doing the forks at the same time anyway.

The suspension upgrade was near the top of the to do list for my beloved black and silver, but now they've moved to the top. It's been running great since the service at CalBMW (where they scratched my new tank and forgot some fairing fasteners). I'm getting close to replacing the new Avon RoadRiders and I'm seriously considering going back to the Macadams. Those were my preferred tire for handling/mileage before the Avons recently became available. With good traction, the Avons are great, but when they slip, the do it weirdly, feeling like the tire is going to tuck under. I have been riding the bike much harder lately, so perhaps I'm just paying much more attention to handling details than I used to. Only way to know for sure is to switch back and compare.
_________________
M N B
1997 BMW K1100LT ABS Special Edition
2003 Husqvarna TE610e
2007 Harley Davidson Road King
2009 BMW F800GS
2011 Husqvarna TE310
2014 Ducati Multistrada Pikes Peak MNB Edition

Flying Duck · Posted: Wed Feb 20, 2008 5:43 pm Post subject:

WD-40 is perfect for this.That's what I'd use. It will serve as both a contact cleaner and will lubricate the spring inside. It's nonconductive so it won't short anything in there.

http://www.wd40jobsite.com/secret_detail.cfm?id=1395&c=&q=&s=1

The reason they warn you to turn things off before spraying electrcial contacts is that it can be flammable as an aerosol spray. In theory, a spark could ignite the spray.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

Geoff · Posted: Thu Feb 21, 2008 2:54 pm Post subject:

I was going to suggest using WD40, too.
_________________
2000 R1100RT
2008 H-D Electra Glide Ultra Classic

mnb · Posted: Thu Feb 21, 2008 6:29 pm Post subject:

My only worry with that was that, while it would lube the plunger (which it probably needs or it wouldn't be sticking), it might penetrate inside the switch and coat the electrical contacts, preventing conductivity.
_________________
M N B
1997 BMW K1100LT ABS Special Edition
2003 Husqvarna TE610e
2007 Harley Davidson Road King
2009 BMW F800GS
2011 Husqvarna TE310
2014 Ducati Multistrada Pikes Peak MNB Edition

Off the grid · Posted: Thu Feb 21, 2008 7:14 pm Post subject:

If anything WD-40 will increase electrical contacts, no?
_________________
Bane of your existence since July 2006
2007 Triumph Tiger ABS. "Sabertooth"
2009 Husqvarna TE610. "The dirty Italian mistress"

Flying Duck · Posted: Thu Feb 21, 2008 9:58 pm Post subject:

Off the grid · Posted: Thu Feb 21, 2008 10:01 pm Post subject:

This is why I love you guys.

And stuff.
_________________
Bane of your existence since July 2006
2007 Triumph Tiger ABS. "Sabertooth"
2009 Husqvarna TE610. "The dirty Italian mistress"

BobZ(IL) · Posted: Thu Feb 21, 2008 10:42 pm Post subject:

OTG,
God that drummer looks familiar, maybe a Foo Fighter?
_________________
'93 K1100LT
'78 R100S
'05 R1200GS
BMWMOA, CRBMWOA, ABC, K11OG #997

Live well, do good work, enjoy the ride.

Off the grid · Posted: Thu Feb 21, 2008 11:06 pm Post subject:

Boromir from LoTR.

On Will Ferrels body.

Who is playing the cowbell player from BoC.
_________________
Bane of your existence since July 2006
2007 Triumph Tiger ABS. "Sabertooth"
2009 Husqvarna TE610. "The dirty Italian mistress"

Jim Brotherton · Posted: Fri Feb 22, 2008 11:03 am Post subject:

Had the same problem with the brake light, stays on intermitly and then goes out. Cleaned the micro switch on the hand grip with WD-40 that problem has never again raised it's ugly head.
_________________
1995 K1100RS
2004 R1150RT