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Technical Chasing electrical gremlins 1955 ford mainline

Discussion in 'Traditional Hot Rods' started by Blacktop-Ranger, May 18, 2021.

  1. So my mainline is driving me a little crazy. I am trying to keep her as original as possible but the 6v system is getting old. currently have a 2 Volt parasitic draw when the car is off and the battery (one month old optima 6v red top ) will only charge to about 5.9 volts. I have cooked two voltage regulators and just replaced it again( the circuit relay gets nice and black ). The generator was rebuilt about 2200 miles ago. I am hoping for some advice. Thank you
  2. G-son
    Joined: Dec 19, 2012
    Posts: 936

    from Sweden

    Two volt parasitic draw? Do you mean two amperes?

    Anyway, if something is drawing current when it shouldn't, find out what and fix it.
    If it doesn't charge as it should, find out if it's a voltage drop between generator-battery, problem with the regulator, problem with the generator, or simply things drawing more current than it is able to supply.

    Those cars don't have many fuses, do they? Pulling one at a time can be used to narrow down what causes the draw, if it's something fed through fuses. Can be a defective generator/regulator too, disconnecting that should show that.
  3. No fuse box from the factory
  4. The lack of a unified fuse panel does make troubleshooting these cars harder... and more than a few circuits aren't even fused.

    First place I'd look is the charging system. Try lifting the wires connected to the 'Bat' terminal on the regulator to see if the drain goes away. Also make sure the factory ground wire from the generator housing to the regulator mounting base is in place and unbroken. If that clears the drain, check each wire to ground with both ends lifted off its connection. The available voltage regulators these days are crapshoots as to quality, I wouldn't rule that out either.

    No joy there? Reconnect those wires and drop the ignition switch down to where you can get at it, and try lifting the wires connected to the 'bat' terminal at the switch. There should be at least two wires connected, one will be incoming power from the regulator, any others will be feeds to the unswitched portions of the harness. These will include all interior/exterior lighting (including the courtesy lights but not the turn signals) and the horn. You can check the switch by reading for continuity between each terminal with the key 'off'. Your meter should show 'open' between each terminal when 'off'. If that's not what you see, the switch is bad.

    Switch OK? Then reconnect the incoming power wire back on the switch. If no drain, then it's the 'other' wire or wires and you'll have to trace those to find the problem.

    Good luck!
    Fabulous50's likes this.

  5. Fabulous50's
    Joined: Nov 18, 2017
    Posts: 452

    from Maine

    How are you checking for a draw? Or is the battery just running down/not able to start the car?
  6. Glenn Thoreson
    Joined: Aug 13, 2010
    Posts: 501

    Glenn Thoreson
    from SW Wyoming

    My guess would be the regulator. The cutout relay could be defective and not opening when the engine is off. Regulators these days are, as stated, a crap shoot and crap is the key word. I know what I would do if it was mine and it's a really easy upgrade. I would spend the bucks for a Powergen alternator. They look exactly like the original generator. I'm not sure if they are a 1 wire design. One wire -- Use the armature wire from your old generator and use it to hook the Powergen alternator to the BAT terminal on your existing regulator.
    String the other wires from the old generator back along the wire loom and neatly tape them to look like they are part of the loom. There you have it. A self regulating, much better alternator that looks like it should. Before doing anything, though, disconnect the BAT wire from the regulator and use a volt meter to check between the wire and the regulator BAT terminal for any voltage. If you get a volt reading with everything in the car turned off, it's a faulty regulator. There should be no voltage detected.

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