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Thread: Splicing new wires into original wire harness

  1. #1
    Junior Member
    Join Date
    Nov 2020

    Splicing new wires into original wire harness

    Hi all!

    I just purchased a 1952 M38A1 in good shape with the original 24v electrical system. At some point in its history, circuit 16 failed between the headlight switch terminal M and the dimmer switch. I can run a bypass wire but I am looking for any tips or tricks to tie it back into the original wire harness.



  2. #2
    Super Moderator LarrBeard's Avatar
    Join Date
    Nov 2014
    Ft. Wayne, IN

    Working with old wiring harnesses is never a fun job. Outer covers have gotten old and frayed and the inner insulation is dried out and cracked. This failure is a bit more of an issue because of the double connector right by the dimmer switch. You can often cause more issues than you solve by twisting and flexing old wires.

    Many failures happen at the connector. Check it over closely. Look for frayed or broken places where the cable may have been bent around a frame member. I do not know if your vehicle has the wires wrapped into a single cable run or not. If there is a single wire you can reach, I have had some luck finding breaks in wires I didn't want to pull out. It is tedious.

    Use a meter that beeps to show continuity or a buzzer type circuit tracer. Connect one probe of your meter to a "good" end. Start at that end and move down the wire a bit. Use a large sewing needle to pierce the insulation and connect the other probe to the needle. If you get a beep - move on down the wire. Once you lose the beep, you have found the first break. An in-line splice usually fixes that. But - keep on looking.

    Wire breaks are like rodents. Where there is one, there is usually another one.

    Or - just bypass the broken wire and use a cable tie to hide the repair away from curious eyes.

    Good luck - let us know what you find and post some pictures!

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