KTM 640A -- lights out

Discussion in 'Thumpers' started by NKOrange, Jun 12, 2013.

  1. NKOrange

    NKOrange Puny homer

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    On the last ride I noticed the headlight on my KTM 640A was off. Went to fix it today. Here are my observations:

    It is not the light bulb, that it fine.

    The high beam is not working.

    The taillight is also off.

    The 10A fuse (#5) of the lights circuit is fine (the obvious culprit, but not in this case).

    The rear break light works, and all other electrics (blinkers, starter etc.) are working fine.

    With a quick inspection I can't see any loose wires.

    Any idea what might be going on?
    #1
  2. psychocandy

    psychocandy Adventurer

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    Check the handlebar switch, I ran into some weird shit. Kinda similar to but the opposite of your problem. No high beam, fuse good, tail light works but brake light doesn't.

    In my case white power (?) lead going into the handlebar switch vibrated off where it was soldered to. I couldn't get the solder to stick, so I need a KTM switch to replace it with. I tried hooking up a generic switch, but the power lead on the KTM is kinda weird.
    #2
  3. bmwktmbill

    bmwktmbill Traveler

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    Check the ground side of the bulb for continuity to negative, work the positive side backwards forwards from the swirch, is there power at the fuse?
    b
    #3
  4. wvrocks

    wvrocks Been here awhile

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    I'm going to put my money on the ignition switch. Mine showed the same symptoms. Take the bottom of it off and dissasseble. There will probably be some loose wires. Resolder or replace as needed. My low beam was out when I bought the bike but that was because the power lead to it had been stretched and the wire was broken inside the insulation.

    I've since rewired both headlights direct from the battery with their own fuses and relays and used the old wiring to fire the relays.

    What year is your bike? Do you have a wiring diagram for it?
    #4
  5. hattah79

    hattah79 .

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    I had the same problem with my 99 640A
    The Ignition switch had melted and the wires no longer touched the terminals
    #5
  6. cneidhart

    cneidhart Adventurer

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    Phoenix, Arizona
    It's the ignition switch.
    Happened to mine, also. The contact point on my switch had become worn. I had a short term fix to the switch and then when it happened again I just added another on/off switch.
    #6
  7. Kawidad

    Kawidad Long timer

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    I have the same problem with my 640E, but it is so intermittent I haven't gotten around to fixing it. I also believe it to be the ignition switch, but haven't pulled it apart yet. All of the fuses are good, as is the light switch on the handlebar, and there is no signs of wire chaffing.
    #7
  8. wvrocks

    wvrocks Been here awhile

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    Its not bad to take apart. The little tabs can be pretty tight but with couple small screwdrivers it will pop open. I was able to resolder mine and I'm not very good at soldering things. Be careful not to get the contact wiring cups too hot as they will move in the plastic switch housing.

    When I had it all fixed, I filled the cup around the wires with silicone to help resist future wire movement. Make sure you have it all working before that step though. It would be a major PITA to pick the old silicone out. I also put a ziptie inside the black plastic dome to reduce the chance of the wires pulling out.
    #8
  9. NKOrange

    NKOrange Puny homer

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    Thank you all the the replies.

    I will dig into the ignition switch tonight, hopefully that will fix it.

    Cheers,
    Nick.
    #9
  10. NKOrange

    NKOrange Puny homer

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    So, I pulled out the switch and sure enough there is a wire dangling in the air. In good style, it is the orange one :rofl

    There is also burn marks around the connection and on the wire sleeve. Since KTM says that a new switch is special order and will take 3 weeks, I'll try to fix this one.
    #10
  11. wvrocks

    wvrocks Been here awhile

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    Do I win a prize? Glad you found your issue.

    #11
  12. Kawidad

    Kawidad Long timer

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    Hmm, now you're giving me pause to reconsider pulling my switch and checking sooner rather than later...............:hmmmmm
    #12
  13. NKOrange

    NKOrange Puny homer

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    So, I took the whole switch assembly apart and found that the other side of the orange wire connection has basically melted into the plastic. No easy fix there.

    What I ended up doing was pull the two wires of the light switch out (orange and green) and hooked them up to an external switch ziptied to the handlebar. Simple fix with only what was quickly available but works great, and the lights are on only when I want them (European style) which is a plus. In the end I will probably get a proper switch since the one I used in not waterproof.

    Debating whether I want to order a whole new ignition switch, since I honestly prefer this setup over the factory one.

    By the way, I have pics of some of the parts and problems, if you want to see them send me a PM.

    Many thanks to all for their input! :bow
    #13
  14. NKOrange

    NKOrange Puny homer

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    Come over to Colorado, the prize is riding mountain passes, I am getting to know more and more of them :evil
    #14