Brake light stays on. Why?

Discussion in 'GS Boxers' started by FotoTEX, May 30, 2011.

  1. FotoTEX

    FotoTEX Long timer

    Joined:
    Feb 22, 2007
    Oddometer:
    3,009
    Location:
    Granbury Texas
    I noticed my brake light stays on. What could the cause be? The bulb filament looks fine, it just stays on brake mode. Is it the brake sending unit? Any help is appreciated.
    #1
  2. jsb223

    jsb223 ADV Rookie

    Joined:
    May 18, 2006
    Oddometer:
    1,730
    Location:
    Waco, Texas USA
    check the micro switches at the front lever and the rear brake...
    #2
  3. electricbear

    electricbear Adventurer

    Joined:
    Feb 27, 2011
    Oddometer:
    34
    Location:
    Port Richey FL.
    Check your hand guards. I had mine come a little loose and it was pressing on the front brake lever. make sure that the handle has sufficient clearance.
    #3
  4. FotoTEX

    FotoTEX Long timer

    Joined:
    Feb 22, 2007
    Oddometer:
    3,009
    Location:
    Granbury Texas
    How do you check the micro switches? And where are they located?
    #4
  5. jsb223

    jsb223 ADV Rookie

    Joined:
    May 18, 2006
    Oddometer:
    1,730
    Location:
    Waco, Texas USA
  6. Kiwirich

    Kiwirich Been here awhile Supporter

    Joined:
    Dec 26, 2007
    Oddometer:
    709
    Location:
    Toowoomba Australia
    You may also want to check the Rear Park light bulb.
    If the Rear bulb blows, the brake light ( also in the Rear Bulb) is used on a low setting.
    When you operate the Brakes, the Brake light comes on Full strength.

    o you have the dreaded "LampF" on the Dash Display ?
    #6
  7. FotoTEX

    FotoTEX Long timer

    Joined:
    Feb 22, 2007
    Oddometer:
    3,009
    Location:
    Granbury Texas
    A BIG thank you for my ADV friends. It was my hand guards that were pressing up against the brake lever. I just tied the bike down to my trailer and it moved the lever too close. Y'all are the best...

    Sometimes the obvious are the easiest way to fix a problem. Signed:A dumb-ass GS riders. Thanks again.
    #7
  8. N-m

    N-m Captain 2 Sexy

    Joined:
    Jan 18, 2011
    Oddometer:
    501
    Location:
    Too Far from My Welder and BMW in South TN.
    1995 R1100 GS

    Now I have this problem. The possible causes on advrider.com and my findings are:

    1. handguard is hitting lever or vice versa - HG is now removed and problem persists;
    2. leaf spring or shiv of metal has moved off the switch allowing the circuit to remain open - both front and rear shivs is in place;
    3. micro switch is not fully closing - I have actuated the switches on front and rear by hand as far as I could push them in and the problem persists;
    4. bulb element is out - with switch in accessory position and brake light cover off bulb has only one element burning and at a lower level of voltage than normal. when switch is moved to the on position both elements light up and the bulb is very bright. Unless there are more than two elements in the tail light bulb the bulb is fine.

    Any other ideas? I am basically grounded until I can get this squared away since I don't want to ride w/o brake lights and the brake light will be perceived as a tail light only.
    #8
  9. rdwalker

    rdwalker Long timer Supporter

    Joined:
    Jan 3, 2005
    Oddometer:
    2,603
    Location:
    The Badlands (of NJ)
    Not too sure what "shiv" means - but I'll take a stab on suggestions, especially since you already did a lot of homework yourself.

    Is the ABS computer sensing your switches? That is, is the ABS warning light going off once you start moving?

    You did not write what bike you have. If you have iABS (with power brake assist), are your brake pumps coming on when you depress the front/rear levers?

    Older bikes have 2-element bulbs, newer have 1-element (driven to full/partial brightness by the computer). If your light is "full bright", the bulb is not the problem.

    My bet: either the front or rear brake switch is not opening. It is a fairly common malady, caused by impact, debris or mud. Switches are known to fail as well: they may not complete the circuit even if mechanically correct.

    You may have to tap into the switch wires to see if the circuit is actually closing/opening.

    Good luck! Robert.
    #9
  10. N-m

    N-m Captain 2 Sexy

    Joined:
    Jan 18, 2011
    Oddometer:
    501
    Location:
    Too Far from My Welder and BMW in South TN.
    1995 R1100 GS with ABS.

    Thanks for the reply. By shiv I mean the thin piece of metal that covers the micro switch. Both of those are in place. The ABS works fine with the battery tender but does not work when I let the battery get low.

    I found this on the MOA forums:

    "Long story short, I think the leaking fluid, shorted the contact switch and kept the brake switch on. Be absolutely sure to give the whole handlebar reservoir/lever assembly a thorough inspection before just replacing a switch, and if you don't feel confident in either repair or have doubts whether it is leaking or not, take it to the shop. No brakes, no fun!"

    Here's a link to the thread:

    http://www.bmwmoa.org/forum/showthread.php?35180-Rear-Brake-light-stays-on

    Based on your post, the above post and the dirt and brake fluid I saw around this area I wonder if I have a slow leak that is causing the switch to short out or causing a short in the wiring?

    Either way I will have to do some more digging tomorrow afternoon. I wonder how hard it will be to remove/rebuild that reservoir? :huh
    #10
  11. N-m

    N-m Captain 2 Sexy

    Joined:
    Jan 18, 2011
    Oddometer:
    501
    Location:
    Too Far from My Welder and BMW in South TN.
    More I have found to check, and for the future reference of new GS owners:

    "The Honorable rideLD has, based on years of following GSpot, compiled the following list; his experience is that almost all failures are one of these five.

    5 things to cause ABS failure.

    1- Lever or pedal failing to travel fully back to the correct position. This is usually caused by the hand guard preventing the front brake lever from fully extending or a pebble or twig preventing the brake pedal from returning to its up most position. An easy way to tell that this is your problem is that your brake light will always be on.

    2- Sensors. If either of your brake sensors fail the brake light will stay on. Severed wires, dirty sensors or melted sensors can cause this failure. If your speedo works then your rear sensor is definitely OK. Make sure your front sensor is clean and wire is not severed.

    3- Fluid levels. Tip overs can cause fluid to leak out of the ABS pump under the gas tank. Pull off the gas tank and top off each of the circuits. This will fix a fluid level related failure.

    4 - Microswitch problems. There is a little tiny switch under the front brake lever and next to the rear brake pedal. You should hear an audible click when you activate either. This switch can fail although it is rare. If your problem is not 1,2 or 3 then this is probably your problem. If the switch is bad your brake light will not activate from the bad switch.

    5- Bad pump unit. Very rare. In fact I have not heard of one failing on the R1200GS yet. There have been a few replaced but these were diagnoses errors and real problem was one of the four items above.
    "

    Found at this link of von Baden's:
    http://www.jimvonbaden.com/BMW_R_FAQ.html

    The above sheds some more light on what Robert was talking about with ABS failures. Thanks for the help.
    #11
  12. rdwalker

    rdwalker Long timer Supporter

    Joined:
    Jan 3, 2005
    Oddometer:
    2,603
    Location:
    The Badlands (of NJ)
    Hmmm... intriguing.

    Your point abuot ABS working OK on full battery: in general, this is normal. ABS will work well normally, but may throw an error code when the battery gets low. Never, never let that happen. Your generation of ABS may wind up with a permanent error code from low battery (there are ways to clear that by shorting pins in diagnostic connector, when you get to that).

    If you think that you have a leak and destroyed the switch:

    - first, eliminate any leaks you have. Search here for advice on seals; check on Beemer Boneyard page for parts or contact them by email.
    - switches are easily replaceable. These are standard microswitches and the whole switch body can be pulled out. If unsure, post a question here; you'll get a lot of replies with how-to pictures.

    However, never fix or replace anything that you do not know is bad. In my business, this is called "shotgunning it"; it has its time and place, but not in your case - yet. You may wind up replacing expensive components or even making matters worse if you do not check the simple things first.

    If the battery is OK and you think that the levers operate the switches:

    a.) listen to the switches, you should hear a faint click.
    b.) test the switches with voltmeter: puncture the wires with sewing needles/pins and prove that they are closing the circuit when levers are operated, with ignition on.

    Regards, Robert.
    #12
  13. N-m

    N-m Captain 2 Sexy

    Joined:
    Jan 18, 2011
    Oddometer:
    501
    Location:
    Too Far from My Welder and BMW in South TN.
    I will be going through the tests you have listed above and hopefully can get something cleaned up or reconnected to the point I am back on the road. I have researched everything you have said above but need to get the light working temporarily until I get can a new set of tires. I have never heard the term "shotgunning" before but am familiar with "parts changer." That approach works when you are dealing with small B&S motors but not when replacement units get in the low $200's. :eek1

    I will let you know how it goes and get a great deal of pictures since they help us and even newer owners than myself. Thanks.
    #13
  14. mouthfulloflake

    mouthfulloflake Not afraid

    Joined:
    Aug 21, 2008
    Oddometer:
    29,679
    Location:
    The Berkeley of Arkansas
    my 95 1100gs has hung a time or two.

    its always been the switch near the foot brake pedal
    I use a credit card, or knife blade to slide it back into position, easy as can be, just sort of odd to diagnose
    #14
  15. N-m

    N-m Captain 2 Sexy

    Joined:
    Jan 18, 2011
    Oddometer:
    501
    Location:
    Too Far from My Welder and BMW in South TN.
    Worked on this for about and hour with much time spent learning about everything under the right hand guard. Long story short I got the problem resolved for now but have a front reservoir leak that has caused the micro switch for the front brake to begin falling apart. I believe the actual problem was the large amount of dirt, trash and crystals preventing the switch from opening and closing that caused the light to stay on. Now that I have cleaned that up the brake light is working.

    Final solution will be to rebuild the reservoir, replace the switch and thoroughly clean everything. I am going to order everything this week.

    I have several pics that I will put up when I get the chance. Thanks for everyone's help.
    #15