Got a bad case of the wiring demons....... Help please

Discussion in 'Trucks [ Eighteen Wheelers ]' started by greaseburner, Jan 11, 2018.

  1. greaseburner

    greaseburner Light Load Member

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    Thanks!

    Problem is cannot find any other wires then those I listed that have power in them. Removed plastic loom further towards cab already then where it was added on to from the stretch.

    What would cause the right turn signal to stop when brakes are applied?

    Thanks again
     
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  3. greaseburner

    greaseburner Light Load Member

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    Have a 12v 30 amp diode coming today if nothing else I think I can make that work, so everything we already have wired already works.
     
  4. kemosabi49

    kemosabi49 Trucker Forum STAFF Staff Member

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    Brake and turn signals run through the turn signal unit for the tractor. So 1 wire to each side powers both brake and signal lights. But the traile has a separate wire for each side signal plus one wire for the brake light.
     
  5. greaseburner

    greaseburner Light Load Member

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    So from the brake switches it goes through the turn signal unit before going to the rear of the truck?
     
  6. spsauerland

    spsauerland Road Train Member

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    Yes. Brake switch then turn signal switch. When switch is moved to left or right turn, stoplamp circuit inside turn signal switch is opened and turn contacts close. This way one side on rear has turn flashing and other is having brake apply.
     
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  7. greaseburner

    greaseburner Light Load Member

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    here's where we are at.

    tried using a diode to get the lights to work, still getting some feed back somewhere, so i've come to the conclusion that we have to do a rewire from signal switch back.unless some one has a better idea

    here's the wiring from the signal switch
    blue and green are both flashing when turn signal is on, nothing when off. blue is connected to whiteish wire with greenish stripe
    green is connected to green
    orange and yellow both flash left, nothing when off
    orange is connected to green wire with white stripe
    yellow wire is connected to yellow wire with black stripe

    red wire is hot when brakes are applied

    black wire flashes and makes blinker flash when we hook up the test light

    can anyone decode all that?

    if we are going to do a rewire from switch back, where are the two brake wires?

    also, how do you get the brake/turns to flash if you have a hot brake light hooked in? Something needs to make it cut in and out. The signal switch has nothing cutting in and out except the turns. There is no brake feed that shows up when the brakes are applied except for the red wire and it's full on hot only when brake is applied.

    thanks
     
    Last edited: Jan 12, 2018
  8. swaan

    swaan Road Train Member

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    Save yourself the aggravation and just put 4 tail lights on the rear of your tractor.
    2 dedicated to the turn signals
    2 dedicated to brake lights.
    Wire the clearance light circuit to all 4.
    Quit beating your head against the wall.
    Done
     
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  9. greaseburner

    greaseburner Light Load Member

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    might have to end up doing that, but i'll still need to run new wires back as the one blinker wire back there has a stop wired in it from some place toward the cab.
     
  10. GrapeApe

    GrapeApe Road Train Member

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    It's been a long time since I worked on L models, so I may be talking out my butt. I vaguely remember needing to pull the cover off a new signal-stat and cut a loop, it was all in the instructions that came with the new switch. Whether or not you cut it depended on if you have a 2 or 4 tail light system (I think), but I don't remember which way was which. It may be just a brain fart, but something to check.

    My thoughts are, if you have a 2 taillight system, the brake switch goes to the signal-stat. If you have a brake light signal at the turn signal switch, focus in that area, the brake lights are the tun signals, so if the turn signals work and there is brake light power at the switch, the problem has to be right there.

    I also vaguely remember a ground connection on those trucks behind the left kick panel that would make screwy things happen with the lights. It was grounded to the sheet metal under the kick panel and had a thick plastic block on it, a resistor or diode type thing. I cleaned that connection many times to fix a goofy problem. I just can't remember the specific issues it caused.
     
    SAR, Oxbow, greaseburner and 1 other person Thank this.
  11. greaseburner

    greaseburner Light Load Member

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    ok, thanks, will look into all that, but where are you calling the kick panel forsure?
     
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