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Thread: 93 K1100RS w/ABS I has a weird electrical problem.

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    Happily Bent dieselyoda's Avatar
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    93 K1100RS w/ABS I has a weird electrical problem.

    I did the engine in my 93 K1100RS and it runs most awesome. I had an ABS I problem that turned out to be the controller. Here is the thing, I can get everything to work but not at the same time.

    My gauges work fine with fuse #1, the top fuse in but the ABS doesn't. If I pull fuse #1, the ABS works great but no gauges.

    I can't find a wiring diagram that integrates the chassis electrics with the ABS circuitry. I am pretty certain that the wiring, grounds, etc. are all good but what I can't find is if there are any components, relays or whatever that are common to both circuits.

    Short of tearing the bike down again and stripping the harnesses open to trace every wire, I don't know where else to look.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Check the voltages going to the ABS with fuse 1 out and then with it in.

    The ABS is very voltage sensitive.

    A dirty ignition switch can severely lower the voltage when a load is placed on it. I've had a switch drop the voltage from a fully charged battery to below 7 volts when the coils and guages were switched on (shouldn't drop at all). Cleaned switch, all is good.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
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    Happily Bent dieselyoda's Avatar
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    Quote Originally Posted by 98lee View Post
    Check the voltages going to the ABS with fuse 1 out and then with it in.

    The ABS is very voltage sensitive.

    A dirty ignition switch can severely lower the voltage when a load is placed on it. I've had a switch drop the voltage from a fully charged battery to below 7 volts when the coils and guages were switched on (shouldn't drop at all). Cleaned switch, all is good.




    OOOOOHHH, never even thought of that one.

    Thanks for the start!!!
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Happily Bent dieselyoda's Avatar
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    Votage pretty damn good.

    I have god voltage, 12.0 at the ABS and all the fuses with no change, fuse in or fuse out. Voltage drop from the ABS module and ignition switch is 0.02V.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Happily Bent dieselyoda's Avatar
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    Getting into this mess...

    I determined that pulling the Bulb Monitoring Unit from the system gives me both ABS and gauges but it's removed from the system. I was also able to find a jumper wire scotch-locked between bulb power and the power to the brake switches. Naturally, I couldn't figure out why the previous owner(s) would do that so I disconnected the jumper.

    I put the BMU back in, fuse one back in, no ABS. Pull the BMU and leave fuse one still in, all seems to work.

    I'm thinking I've got a bad BMU but no spare to try which means buying one somewhere to confirm that I'm right.

    My big question is what does the BMU actually do? I took it out of the case thinking it was just a relay. It looks pretty damn electronic.

    I've got another 6 months to figure this out so any help will be appreciated.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Quote Originally Posted by dieselyoda View Post


    My big question is what does the BMU actually do? I took it out of the case thinking it was just a relay. It looks pretty damn electronic.
    The bulb monitoring unit tells you whether your brake light, taillight, front (lever) brake switch, and rear (pedal) brake switch are all functioning properly. When first starting the bike, the warning light in the middle of the instrument cluster lights up red. After applying and releasing the front and rear brake separately, it senses the proper resistance in each curcuit and turns out the light. If an open curcuit is sensed (bad switch, bad bulb, bad socket connection) the light stays on.


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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    Happily Bent dieselyoda's Avatar
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    Quote Originally Posted by 98lee View Post
    The bulb monitoring unit tells you whether your brake light, taillight, front (lever) brake switch, and rear (pedal) brake switch are all functioning properly. When first starting the bike, the warning light in the middle of the instrument cluster lights up red. After applying and releasing the front and rear brake separately, it senses the proper resistance in each curcuit and turns out the light. If an open curcuit is sensed (bad switch, bad bulb, bad socket connection) the light stays on.


    Doesn't that go to something like a human appendix? Not sure why it's really there? I check my light on my other bikes routinely and when the bulb is out, that light doesn't work.

    I can't test ride the bike as there is a foot of snow/ice on the ground and the tires REALLY need to be replaced. Best guess, what would happen if I left the BMU disconnected?
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Quote Originally Posted by dieselyoda View Post
    Doesn't that go to something like a human appendix? Not sure why it's really there? I check my light on my other bikes routinely and when the bulb is out, that light doesn't work.
    I'm sure you don't check the lights EVERY time you stop for breakfast, gas, lunch, photo-op, gas, etc. during a high mileage day. This does. Bulbs and switches don't just fail BEFORE you leave your house. It's good to have.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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    Quote Originally Posted by dieselyoda View Post
    I can't test ride the bike as there is a foot of snow/ice on the ground and the tires REALLY need to be replaced. Best guess, what would happen if I left the BMU disconnected?
    You have been determining that the ABS is not functioning by doing the bulb check routine (apply and release front and rear brakes separately) and then going out and getting the bike up to at least 10 mph , correct?



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  10. #10
    Happily Bent dieselyoda's Avatar
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    Quote Originally Posted by 98lee View Post
    You have been determining that the ABS is not functioning by doing the bulb check routine (apply and release front and rear brakes separately) and then going out and getting the bike up to at least 10 mph , correct?



    Most correct. Riding a very naked K1100RS around the block has my neighbours wondering if they live in a good neighborhood or the kind that runs chop shops.

    If I leave the BMU out, I just loose that feature?
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Yoda,

    PM sent.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  12. #12
    Happily Bent dieselyoda's Avatar
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    My BMU guts.

    Inside of my BMU, Look closely for the burnt straps.
    Attached Images Attached Images
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  13. #13
    Registered User 58058D's Avatar
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    If that is not 'the' problem.....certainly it is 'a' problem.....time for that new BMU.
    I think congrats are in order for your persistance at finding the problem.
    Jim Douglas '00 K1200RS >135,000 miles my primary bike again,
    Gone: '09 K1300S sold @ 22k mi, '93 K1100RS traded @ 78k mi, '85 K100RS sold @ 44k mi
    '06 Kaw 650R track bike sold
    http://www.seagullbb.com/

  14. #14
    Happily Bent dieselyoda's Avatar
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    Replacement BMU received, tried, dunno.

    98Lee was gracious enough to lend me a BMU and send it to Canada. If it works, a quick fair payment and I could close my comments on this post.

    First catch, parcel arrived in the hands of our Border Protection folks, torn open, handed to me and asked, "is this yours?" I said yes and needed to explain what it was, show them the bike and the other cooked part. I asked what the hassle was about and they said, "BMU, Bomb Making Unit". Thanks for using that acronym on the package Lee.

    Without the BMU in the system, the ABS light and the Bulb light flash together. The ABS does work and my gauges work without the BMU. No codes in the ABS controller. I installed the BMU from Lee, the lights flash alternately. So I'm thinking I have a problem still.

    Check the codes in the ABS, replacement BMU out or in, no codes! So I'm ready for a test ride. Problem: one foot of snow on the ground and -20C. New Problem, if I install a ski on the front tire and chains on the rear tire, would the ABS even be an issue?

    Question, functioning ABS 1 and everything else working properly, do the red lights flash simultaneously or alternately?
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Quote Originally Posted by dieselyoda View Post

    Question, functioning ABS 1 and everything else working properly, do the red lights flash simultaneously or alternately?
    I BELIEVE they flash simultaniously but not sure (the one ABS K75S that I own is not on the road yet).

    I think if you go through the bulb check sequence, you will end up with only one light on.

    Get up to over 4mph and the ABS will self check and shut off the other light (you might have to do the ABS reset after all the messing around that you've done).
    http://www.ibmwr.org/ktech/abs-reset.shtml. I would use at least 30 seconds instead of 8.

    Sensor clearances have been verified, correct?




    Last edited by 98lee; 12-03-2014 at 02:57 AM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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