Softail runs great until lights are turned on! HELP??

Discussion in 'Electrical' started by mrbeefcak, Jan 19, 2010.

  1. mrbeefcak

    mrbeefcak Member

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    Sorry but im trying to post a new subject and can NOT find the NEW POST!! can you help me?
    Joe 89 Softail

    Hello
    I have a 1989 Softail factory custom
    It runs great until I turn the light switch to on position, Then it sputters,craps out, and eventually fouls plugs!!
    It has new wires,plugs, new Ign. switch,fuel lines, and battery, the charging system is working properly as well.
    It has been in the local shop for three days and they can not figure it out!!
    Please HELP if anyone has had this problemb.
    Thanks
    Joe:small3d023::newsmile047::newsmile09::bigsmiley6:
     
    Last edited by a moderator: Jan 19, 2010
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Sounds like you have a short in that light circuit. Unfortunately, grab yourself a DVOM and a probe, and start isolating the problem. Start at the switch.

    TQ
     
  3. bikerdad

    bikerdad Junior Member

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    It might be the light bulb itself. It is rare, but I have seen bulbs fail to a short circuit instead of open. It sounds like you already replaced the wiring, try it with the bulb removed.
     
  4. mrbeefcak

    mrbeefcak Member

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    We have removed the bulb,unpluged the rear tail & turn lights and still shorts ign. YUK!!
     
  5. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    By "new wires", I assume you mean new sparkplug wires, right? If so, I suggest that you trace the wires from the switch to the controller, and then from the controller to the lights. When you look at the controller (probably under the seat), does it look burnt? You can check your wires with an DVOM by checking for continuity to ground. Disconnect both ends of the wire and then check both ends (one at a time) to a good ground (like the battery negative terminal!). Any resistance reading below infinite is bad, especially zero!

    TQ
     
  6. Chopper

    Chopper Senior Member

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    I think on that year they had breakers under the dash panel, is there a chance the extra draw of the lights are causing a weak breaker to act up?
     
  7. mrbeefcak

    mrbeefcak Member

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    I will check with the mec. and see if he did that check.
    Thanks
     
  8. maine-e-axe

    maine-e-axe Junior Member

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    Sounds like deadshort to me and it must be a pretty big wire, have you had the ign.switch mest with lately or maybe circuit braker is toast. Take the dash off and look for cooked wires, the circuit brakers are under there as well, between the tanks. thats my guess.:newsmile047:
     
  9. rydahog

    rydahog Active Member

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    so after you turn on light it sputters etc,,,but NO fuses are blown? then its not a short...if it was it would blow a fuze somewhere..
     
  10. Robert Walter

    Robert Walter Member

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    Just because the Ign. switch is new doesn't mean it's good !!Check it out with a meter.
    Good luck