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Thread: Melted Harness

  1. #1
    Registered User kbike's Avatar
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    Melted Harness

    Just a bad light bulb, that what I said to myself when I noticed the light for the fuel gauge on my 1996 K1100LT went dark last week
    I went ahead and pulled out the lamp and through it in my pocket to pick up a new one when time permitted.

    Went to take out bike today and turned the key and smoke started to come out from below the fuel gauge. I shut down and took a look and found that when this lamp is removed the light fixture shorts to ground. The lamp pushes against the center pin when installed and lock it back so it would not touch the hot lead, strange design.

    Instead of taking out a fuse it caused the cable harness to melt, there are four wires from the fuel gauge plug going into the what looks like the main harness located in the front of the bike under the tach and speedo gauges. The wires are melted to each other all the way up to where they go into the taped section under the front where this harness disappears into the main harness.

    I talked to someone at the local BMW dealer just before they closed tonight and they mentioned a half harness where it plugs into the main harness might just be melted and that part is 70 dollars, is there a point where it connects to the main harness. After looking it seems it goes right into the taped group of wires under the front gauges.

    Has anyone changed this out on their own or should I bring to the dealer and take out a another mortgage to pay the bill. This one looks like it will cost big time
    Any help would be appreciated

    Rich
    Rich G.

  2. #2
    Blocking the slow lane
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    I replaced the entire wiring harness in my K75 in six hours. Its pretty easy, just a bit time-consuming.
    Jon Diaz
    BMW K75/K12GT
    BMWMOA Ambassador

  3. #3
    A bozo on the bus deilenberger's Avatar
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    Re: Melted Harness

    Originally posted by Kbike
    Just a bad light bulb, that what I said to myself when I noticed the light for the fuel gauge on my 1996 K1100LT went dark last week
    I went ahead and pulled out the lamp and through it in my pocket to pick up a new one when time permitted.

    Went to take out bike today and turned the key and smoke started to come out from below the fuel gauge. I shut down and took a look and found that when this lamp is removed the light fixture shorts to ground. The lamp pushes against the center pin when installed and lock it back so it would not touch the hot lead, strange design.

    Instead of taking out a fuse it caused the cable harness to melt, there are four wires from the fuel gauge plug going into the what looks like the main harness located in the front of the bike under the tach and speedo gauges. The wires are melted to each other all the way up to where they go into the taped section under the front where this harness disappears into the main harness.

    I talked to someone at the local BMW dealer just before they closed tonight and they mentioned a half harness where it plugs into the main harness might just be melted and that part is 70 dollars, is there a point where it connects to the main harness. After looking it seems it goes right into the taped group of wires under the front gauges.

    Has anyone changed this out on their own or should I bring to the dealer and take out a another mortgage to pay the bill. This one looks like it will cost big time
    Any help would be appreciated

    Rich
    I'm not intimately familiar with the K11 harness - there is no such thing as a 1/2 harness on K75's or K100's. The main harness is the main harness and new it's more than the bike is worth.

    There is a small sub-harness that plugs into the fuel (and temperature) gauges if you have them. If only this is melted you can replace just it - but it doesn't sound like that from your description.

    Your best bet - a used harness. Most aftermarket parts places charge 1/2 of new for one... which still is in the region of $300-400. I'd look at the IBMWR marketplace (and join the list if you're not on it - and ASK on the list) for a used harness. Most likely MUCH cheaper.

    I replaced my K75S harness - got the harness for free from a chap in San Francisco who enjoys my projects, and it took about 6 hours or so to mark/remove/replace... I was gilding any lillies I found whilst doing it (like waxing the frame where you can't get to it with the harness in place..)

    Best,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  4. #4
    Registered User kbike's Avatar
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    sub-harness

    Thanks for the reply Don

    I talked this over with a local BMW dealer and it looks like it is the sub-harness that goes from the fuel gauge to the tank.

    He mentioned that it goes to the right side of the tank and I should remove the gas tank for better access.
    I had followed the burnt harness as far as could to underside of the handlebars where it went into a group of cables covered by tape. At that point I had backed off till I could get some more info.

    The dealer would not be able to look at the bike till the end of July if I wanted him to repair it, not good.

    Looks like another lost weekend of riding while I tear apart the bike to replace this sub-harness.

    Bottom line this never should have happened, the lamp socket is a poor design. There is no way that the hot wire should ground itself when the lamp is removed, and if some reason a short did develop the fuse should have gone before any damage was done
    This bike has a 10-fuse system and not a single fuse opened.

    That is BS.

    Thanks again
    Rich
    Rich G.

  5. #5
    A bozo on the bus deilenberger's Avatar
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    Re: sub-harness

    Originally posted by Kbike
    Thanks for the reply Don

    I talked this over with a local BMW dealer and it looks like it is the sub-harness that goes from the fuel gauge to the tank.

    He mentioned that it goes to the right side of the tank and I should remove the gas tank for better access.
    I had followed the burnt harness as far as could to underside of the handlebars where it went into a group of cables covered by tape. At that point I had backed off till I could get some more info.

    The dealer would not be able to look at the bike till the end of July if I wanted him to repair it, not good.

    Looks like another lost weekend of riding while I tear apart the bike to replace this sub-harness.

    Bottom line this never should have happened, the lamp socket is a poor design. There is no way that the hot wire should ground itself when the lamp is removed, and if some reason a short did develop the fuse should have gone before any damage was done
    This bike has a 10-fuse system and not a single fuse opened.

    That is BS.

    Thanks again
    Rich
    Just a FWIW - NONE of the bulbs on a K bike are fused.. including instrument lights. And the design of the socket used on the auxillary guages - while not great - is a VERY common one. I've seen the exact same socket on numerous cars - used for the instrument lights.

    Guess they figured you'd notice that it could short when you removed the bulb.

    Hopefully the melted down part is just the subharness for the instruments.

    Best,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  6. #6
    A bozo on the bus deilenberger's Avatar
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    Re: sub-harness

    Originally posted by Kbike
    Thanks for the reply Don

    I talked this over with a local BMW dealer and it looks like it is the sub-harness that goes from the fuel gauge to the tank.

    He mentioned that it goes to the right side of the tank and I should remove the gas tank for better access.

    Rich
    Did a bit of snipping. The '96 K-LT uses a small subharness that is for both the oil pressure gauge (or temp gauge) and the fuel guage. Dunno which side the subharness plugs into - but it spans across the bike under the tank... so you do have to remove the tank to follow/replace it.

    I find a PN of 61 11 1 459 767 for this subharness.. but if you order one, check the use with your dealer's parts guy first.

    Best and hate to see someone not riding. If needed - while waiting for the part - you could just disconnect it where it plugs into the main harness. That would also tell you if that is where the damage ends.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  7. #7
    Registered User kbike's Avatar
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    Harness

    Thanks once again for the reply Don, I appreciate the additional
    Information.

    I took off just about everything on the bike today but I am still lost.
    Removed the seat, front windshield, side panels, gas tank, radio,
    and just about everything else that was in the way.

    Even after all this it is still a nightmare trying to follow the harness, the melted harness goes to the front of the this bike then goes into a taped group of wires. When I cut back this tape it looks like a bunch of separate single wires that are taped together.
    When I try to follow this harness it goes down along the handlebars and back under the where the tank was sitting. It looks like it goes into an another large group of taped up cable going to the back of the bike with breakouts along the way.

    I cannot find any kind of sub-harness for the gauges under the tank area, I went to the dealer and received conflicting advice again, the parts guys show a part that fits your description. (A Sub-harness) But then the service manager took me in the back and had a K bike apart and pointed to the connector for the tank and said that is what needs to be replaced. It does not make any sense, What technique is used to follow the wires through
    the taped up harness, if you try to cut it back you can damage the other wires and if you try to outboard new wires you still have to find out where they go.

    Thanks again
    Rich
    Rich G.

  8. #8
    A bozo on the bus deilenberger's Avatar
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    Re: Harness

    Originally posted by Kbike
    Thanks once again for the reply Don, I appreciate the additional
    Information.

    Even after all this it is still a nightmare trying to follow the harness, the melted harness goes to the front of the this bike then goes into a taped group of wires. When I cut back this tape it looks like a bunch of separate single wires that are taped together.
    It sounds a lot like you're headed into the main harness at this point.

    When I try to follow this harness it goes down along the handlebars and back under the where the tank was sitting. It looks like it goes into an another large group of taped up cable going to the back of the bike with breakouts along the way.
    I think you just described the main harness..


    I cannot find any kind of sub-harness for the gauges under the tank area, I went to the dealer and received conflicting advice again, the parts guys show a part that fits your description. (A Sub-harness) But then the service manager took me in the back and had a K bike apart and pointed to the connector for the tank and said that is what needs to be replaced. It does not make any sense, What technique is used to follow the wires through
    the taped up harness, if you try to cut it back you can damage the other wires and if you try to outboard new wires you still have to find out where they go.

    Thanks again
    Rich
    If your K bike came with the gauges as stock, it wouldn't surprise me to see the wiring for them included in the main harness. BMW does that sort of thing (well known on the car side - they build the harness to spec for the accessories installed on the vehicle).

    And that's what it sounds like to me.

    So - what to do...

    Two choices I can see:

    1. Start clipping the tape off and following the melted wires back to where they are no longer melted. BTDT on my K75S after a headlight modulator installed by the past owners mechanic melted down more than a bit of the harness. I then cut out the melted wiring, one by one and spliced in replacement wiring to bridge the melted down part.

    This worked for a good period of time, but I was keeping my eye open for a used replacement harness. Finally I started getting some odd electrical problems (power cutout to some of the accessories) so I decided to get serious about finding a replacement harness.

    Thanks to the IBMWR - I found one, which ended up costing me absolutely nothing (longish story why it was free.. it started out at $50..)

    2. Do what I eventually did - find a replacement harness and replace it.

    I never felt terribly confident in the harness when I travelled some distance from home - even though I'd been doing electronic work for decades (a LOT.. ummm.. close to 5 decades..)

    Sorry there isn't any magic here.. but my best advice is - start looking for a replacement harness.

    Best,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  9. #9
    Registered User kbike's Avatar
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    Harness

    Don

    It does not look good, traced the burnt wire back in the harness
    today.

    The 4 wires that come off the plug for the gauge are brown, yellow, green/black, and silver/blue.
    The brown wire goes to the taped up batch of wires under the front handlebars and tie together, that wire is bad but I can replace it. The yellow and green seem intact at this point and do not show any kind of short when checked with an ohmmeter.

    The one that is a real problem is the silver/blue, its looks melted and still reads low resistance to the brown (ground).
    Looking at the wiring diagram for the bike this wire goes the
    same point as the same color cable from the temp gauge, then it ties into the handbrake switch and also the bulb monitoring device (whatever that is).

    I have cut into the harness pretty good by now and do not how much further I can go. If there was a way to find out where this wire terminates I could try to bypass it. To replace the wire going to the two gauges would be no problem but I can not tell how it arrives at the other locations.

    You mentioned you replaced the wiring harness on a K75, have you ever done on a LT and if so how bad is it to do.
    Does the harness come pre-wired to the electric box or do you have to wire it into that as well.

    I am debating to put it all back together and dropping it off at the dealer and hope that they can get to before it starts to snow and of course then I would also have to take the second mortgage to pay for it.

    The worst part this is all because of a 50-cent lamp going bad.

    Thanks again,
    Rich G.
    Rich G.

  10. #10
    A bozo on the bus deilenberger's Avatar
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    Re: Harness

    Mike - thought I had replied to this yesterday, but don't see the reply here anywhere..

    Originally posted by Kbike
    Don

    It does not look good, traced the burnt wire back in the harness
    today.

    The 4 wires that come off the plug for the gauge are brown, yellow, green/black, and silver/blue.
    The brown wire goes to the taped up batch of wires under the front handlebars and tie together, that wire is bad but I can replace it. The yellow and green seem intact at this point and do not show any kind of short when checked with an ohmmeter.
    FWIW - Brown wires on any BMW harness (cage, car) are always ground connections.


    The one that is a real problem is the silver/blue, its looks melted and still reads low resistance to the brown (ground).
    Looking at the wiring diagram for the bike this wire goes the
    same point as the same color cable from the temp gauge, then it ties into the handbrake switch and also the bulb monitoring device (whatever that is).
    Sounds as if it's providing power to those circuits. The bulb monitor is there to tell you if your brake light switches aren't working or if a rear bulb has burned out. It's the reason the brake warning light on the dash doesn't go out until you use both brakes once.


    I have cut into the harness pretty good by now and do not how much further I can go. If there was a way to find out where this wire terminates I could try to bypass it. To replace the wire going to the two gauges would be no problem but I can not tell how it arrives at the other locations.

    You mentioned you replaced the wiring harness on a K75, have you ever done on a LT and if so how bad is it to do.
    Never did an LT. Should be more or less the same sort of project except there is a lot more plastic to remove.

    The way I did it was:

    1. DIGIPICS of everything concerning the wiring - including the inside of the electrical box, etc.

    2. NUMBER every connector, every relay, every socket - and put corresponding number on the other side of each. I then went through the new harness and matched up connectors (by position, shape, size, color) with the old harness and put matching numbers on the connectors/sockets/etc.

    Then it was just a matter of removing the old harness and installing the new one on the frame and connecting the numbers.


    Does the harness come pre-wired to the electric box or do you have to wire it into that as well.
    Not sure what you mean when you say "pre-wired" - if you mean does it come with the Ebox? Nope.

    If you mean is all the wiring done and all you have to do is swap everything out of the box and then back in? Then yes.. that's basically it.


    I am debating to put it all back together and dropping it off at the dealer and hope that they can get to before it starts to snow and of course then I would also have to take the second mortgage to pay for it.

    The worst part this is all because of a 50-cent lamp going bad.

    Thanks again,
    Rich G.
    I'm a bit afraid of what the final bill for this might be if you go the dealer route. I don't think they'll want to do a used wiring harness, but guess you never know - might be worth asking first.

    I would expect labor on the job to be 4-6 hours. A brand new harness will set you back something in excess of $700 and may take weeks to get from Germany.

    HTH,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  11. #11
    Registered User kbike's Avatar
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    Don

    Thanks again for the help,

    I had a day off and worked on the bike yesterday, the burnt wires have been replaced as far into the harness that I was able to go.

    Its not to bad, the brown wire went into a tie point with other grounds and had been melted to that point also the hot(silver/blue) had to be replaced pretty deep in the harness.
    BMW had a pair of the silver/blue running through the harness
    and where it split to go the Fuel and Temp gauge I replaced the one going to the Fuel gauge.

    One thing the dealer did do for me was recommending a rubber tape by Scotch, 2242 , to use to repair the harness after cutting the shield. The tape works great, it only sticks to itself and can be unwrapped if needed.

    Took the bike out last night for the first time in 3-weeks and everything checks out fine so far.

    I still think that BMW made a big mistake in using this type of lamp socket. Although you mentioned that some cars use the same type at least the cars are fused, I also installed some in line fuses on the bike (like BMW should have done)

    Thanks again
    Rich G.
    Rich G.

  12. #12
    A bozo on the bus deilenberger's Avatar
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    Originally posted by Kbike
    Don

    Thanks again for the help,

    I had a day off and worked on the bike yesterday, the burnt wires have been replaced as far into the harness that I was able to go.

    Its not to bad, the brown wire went into a tie point with other grounds and had been melted to that point also the hot(silver/blue) had to be replaced pretty deep in the harness.
    BMW had a pair of the silver/blue running through the harness
    and where it split to go the Fuel and Temp gauge I replaced the one going to the Fuel gauge.
    Great!


    One thing the dealer did do for me was recommending a rubber tape by Scotch, 2242 , to use to repair the harness after cutting the shield. The tape works great, it only sticks to itself and can be unwrapped if needed.
    That's a neat tape.. if you want to put the harness back into what it looked like before you took all the wrapping tape off it - you need cloth based friction electrical tape.

    I once built a BMW harness (long story about adding ABS to an '85 K100RT I owned) - and wrapped it first with vinyl tape.

    Found out why BMW didn't use vinyl tape - it doesn't bend well. Had to get some of the cloth based tape - unwrap it and re-wrap it.



    Took the bike out last night for the first time in 3-weeks and everything checks out fine so far.

    I still think that BMW made a big mistake in using this type of lamp socket. Although you mentioned that some cars use the same type at least the cars are fused, I also installed some in line fuses on the bike (like BMW should have done)
    I suspect the reasoning they use is - they don't want to be liable for the headlight going out suddenly if there is a short. I'd have to guess they would rather have the headlight slowly dim as the wiring burns up - giving you a chance to get to the side of the road. Unfortunately - other lights are on the same circuit.

    I added headlight relays to my K75S with an in-line fuse. I doubled the size of the fuse (used a 20A instead of a 10A) so that a REAL short would blow the fuse - but a temporary overload wouldn't.

    I also added auxilary lights to the bike since I don't like to depend on a single light source.



    Thanks again
    Rich G.
    Glad to hear it's back on the road. If it was me - I'd keep an eye out on the IBMWR marketplace for a replacement harness.. and if you find it cheaply enough, get it and plan to install it when you'd normally have some downtime (dunno if you have winter.. we do in NJ!)

    Best,
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

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