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lectrical problem...

Discussion in 'Shop Talk' started by DIYDAVE, Oct 10, 2019.

  1. DIYDAVE

    DIYDAVE Senior Member

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    Just installed a new trailer axle, with brakes, on my old box trailer. Was gonna hook up the wires to the brakes, today, took a continuity tester (HF simple model, AA battery and lightbulb, inside a circuit tester probe), here's the situation. 2 wires come from the front, black and white. White wire shows good continuity to the ground (bulb glows bright!) black, shows a weak connection to ground (little teeny glow of the bulb). Disconnected the 3 black wires, at the e-box, up front, still get the teeny glow. My suspicion is that the wire from the box, to the axle, has a partial short, and needs a new wire strung, between box, and axle. Any thoughts?

    Another question, on the new axle, both wires are white, and neither shows continuity, to ground, when tested with the same continuity tester. Does it matter which way the wires are connected, to the trailer's brake loop?
     
  2. RZucker

    RZucker Senior Member

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    Not an absolute expert with electric brakes, the coils in the wheels don't care about polarity. On your trailer white is most likely the ground wire, when you got the slight glow on the black wire were you connected to the tow vehicle? Do you have a break away switch?
     
    Last edited: Oct 10, 2019
  3. DIYDAVE

    DIYDAVE Senior Member

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    No, no tow vehicle connected, and yes, have a breakaway. When I disconnected the 3 black wires, the plug and the breakaway were removed from the loop, I think the short has to be in the wire, from the e-box, to the axle. The wire was mashed in half, just behind the front axle, and the back part of the loop shows no continuity with the ground.:eek:
     
  4. DIYDAVE

    DIYDAVE Senior Member

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    well, got the replacement wire in, today, didn't have enough time to hook up the axle wires, but continuity-wise, it fixed the problem, so I guess its all good. Last 1 of these I hadda do was like 5 years ago, so I'm a little outta practice... Thanks for the input, RZ!:D
     
    RZucker likes this.
  5. RZucker

    RZucker Senior Member

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    For some reason mashed wires are common on trailers. I've worked on a few that ran the wire down between the deck boards those were a lot of fun to chase the problem down.