Wiring issue, help needed.

Discussion in 'The Garage' started by DirtDabber, Jul 21, 2012.

  1. DirtDabber

    DirtDabber cultural illiterate

    Joined:
    Jul 10, 2007
    Oddometer:
    8,442
    Location:
    Way, Way North GA
    R1200CLC with a Hanigan Sidecar

    Problem: running lights and brake lights flicker, indicator lamp shows wiring problem

    Here is the wiring diagram.

    [​IMG]

    I have disconnected the harness and tried to chase a short to ground without finding a fault.

    If I switch the tail lamp and brake lamp terminals on the tail lamp, the lights flicker faster due to the higher draw of the brake lamp.

    I have added an extra ground wire with no improvement.

    If I disconect either the tail lamp or the spot lamp the problem goes away.

    Upon startup there is no problem for 15 seconds then the lights start a steady flicker about 1 second each, with the tail lamp/brake lamp wires switched the flash is about 1/3 second.

    The flicker flashes the brake bar on the trunk lid of the sidecar even though the brakes are not activated.

    I have isolated each harness of the run/brake and spot light and found no fault to ground.

    I am at a loss and drinking beer to try and solve the problem......
    #1
  2. MeanMoe

    MeanMoe one really mean cat

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    Just a stab in the dark, is there a kasan brake modulator in the fuse box?
    #2
  3. DirtDabber

    DirtDabber cultural illiterate

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    The brakes do not modulate. I will look in the fuse box to make sure there is not a modulator unit.
    #3
  4. Garp

    Garp Long timer

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    Is there a solid ground connection between the bike and the sidecar?
    #4
  5. DirtDabber

    DirtDabber cultural illiterate

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    Yes, there is a dedicated ground and I added an extra ground jumper just to make sure with no improvement.
    #5
  6. Beezer

    Beezer Long timer

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    sounds to me like it's pulling power from the output side of the flasher...
    #6
  7. SuchesRider

    SuchesRider Just Do It!

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    Hi DD. :waveSounds like you are on the right track with the beer drinking..... :1drink SR
    #7
  8. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

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    Does the flicker change with the engine RPM? Is it a rhythmic flicker or erratic, more like an open wire somewhere?

    If the wiring is in good shape and you have already checked every single little connection, it could also be caused by a failing diode/winding in the alternator. I would check voltages and just for grins when it is flickering use some jumper cables to hook up to a fully charged battery and see if the flicker goes away.
    #8
  9. DirtDabber

    DirtDabber cultural illiterate

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    The flicker does not change with RPM.

    I disconnected the ground wire from the tail lamp and the light stayed on.....

    Soooooo..... I must have a brake wire and running light wire pinched together somewhere in the system just enough to feed back running light current through the the brake lights and then to ground.

    Everything is run through conduit so time to dismantle the harness and start looking. Sam Adams Summer Ale should do the trick.
    #9
  10. S2P

    S2P Been here awhile

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    since the tail,marker and spot are all on the same pos lead I would start there. It may have melted due to amp draw .
    #10
  11. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

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    If it is running through conduit, a trick is to use your safe cracker touch and lightly tug on a wire with one hand and feel it move at the other end of the conduit with the other. If some wires are binding you may be able to feel where they are doing it. Since you don't have much to lose, if you can isolate the pinched wires a firm tug can sometimes free them, or guide you to the bolt that is pinching them. When it works, it is a bit faster than disassembling everything.

    Good luck!
    #11
  12. DirtDabber

    DirtDabber cultural illiterate

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    Thanks, I have isolated everything in the sidecar harness. I suspect it is in the bike harness to the sidecar disconnect.
    #12
  13. DirtDabber

    DirtDabber cultural illiterate

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    Just an update to the problem....


    When the sidecar was attached the following load was added to the running light harness lead.

    Sidecar running light.
    Front marker light.
    Front spot light.

    The additional load was tricking the BMW sensors that there was a problem with the light circuit. By removing the spot light and tying it in with the headlight circuit it solved all the issues. Of course by then I had inspected every inch of wiring harness looking for a ground. :lol3
    #13