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Need Help with Electrical Problem

Discussion in 'The Hokey Ass Message Board' started by blue 49, Aug 25, 2012.

  1. blue 49
    Joined: Dec 24, 2006
    Posts: 1,225

    blue 49
    from Iowa

    A couple of nights ago I was driving through the second bend of a sweeping "S" curve near my home when my headlights went out for no apparent reason. I could not see a thing and nearly put my '36 in the ditch. I managed to get stopped on the shoulder and put my 4 way flashers on and they worked, as well as my brake lights. As i was sitting there, the headlights came back on and I slowly tip toed the rest of the way home.

    The truck has 14,000 miles on it (probably well under a 1,000 after dark), a Rebel Wire harness and a "new out of the box" headlight switch I got from a parts store that went out of business about 20 years ago. I'm running halogen sealed beam lights.

    Since nothing but the headlights was affected, I'm assuming the switch is the problem. Anyone have any input? Thanks.

  2. Did the tailights go out also? Could also be the dimmer switch.
  3. rotenjon
    Joined: Oct 26, 2009
    Posts: 111


    Do you have a relay for your lights? or just straight off the switch.
  4. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    from florida

    Some headlight switches will do that when they heat up. Fords seem to come to mind that have a thermal circuit breaker inside and when they get hot it kicks open, then will reset when it cools down. As the switch ages the circuit breaker gets weaker and trips easily.

    I had some car or other over the years (I think it was an 84 Crown Vic) where I was driving along and all of a sudden the headlights went off. :eek: They came back on, but a while later they did the same thing. I replaced the switch and the problem went away.

    Last edited: Aug 25, 2012
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  5. Rockit53
    Joined: Aug 4, 2005
    Posts: 115


    I had a similar problem in my '53, the headlights would shut off and then come back on, and then as I drove more, they would almost blink. I thought it was a bad ground, but it turns out that since I didn't have a relay in the headlight circuit after I rewired it, the thermal fuse in the switch was opening because of the draw through it. Ordered a relay kit from Rebel, hasn't happened since.
  6. i would look for either a loose wire or that switch is bad. i have had the cheapy little after market switches go bad but they never were intermittent.
  7. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

    Most likely the headlight switch has the thermal circuit breaker in it. Halogens probably draw more current than the switch is designed for. Check your wiring to make certain that nothing is rubbing that could ground out when hitting a bump.
  8. dirt t
    Joined: Mar 20, 2007
    Posts: 4,568

    dirt t
    from Kingman,AZ
    1. HAMB Old Farts' Club

    With halogens I would use a relay to control power to the headlights.Of course the relay is controled by the headlight switch.
  9. 100% agreement on the relay and likelihood of thermal protected circuit.
    Should be a repeatable occurrence.
    Be sure the ground chain is good back to battery
  10. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope

    Ditto on the thermal cutout. My '64 Merc did that after I put Lucas lights in it years ago. I went back to stock incandescents and the problem went away. Lucas lights were illegal here then anyway. not sealed beams. Times do change, don't they?
  11. I agree, the circuit breaker is the problem and wiring your headlights with a relay should fix it. Especially important if you're running halogen headlights with an older switch. The halogens would be pulling too many amps through the switch. With a relay, the headlight switch only has to deal with amperage needed to operate the relay, not the amperage needed by the headlights. As an added bonus, putting a relay in the system will probably make your lights a little brighter. A bad dimmer switch can cause the headlights to suddenly go out (had that happen once on my '55 Ford when I was in high school), but if the dimmer switch was the culprit, your lights would not have worked again after it cooled off.
  12. George/Maine
    Joined: Jan 6, 2011
    Posts: 949


    Did you lose both high and low.Best thing is check the ends of ever connection give a tug and see if you can pull off.If foot switch check it out,and any loose wires.
  13. flathead4d
    Joined: Oct 24, 2005
    Posts: 884


    It's the damn halogen headlights. Draw too much current and kick out the circuit breaker. Change the headlights or install a relay in the circuit.
  14. blue 49
    Joined: Dec 24, 2006
    Posts: 1,225

    blue 49
    from Iowa

    Thanks for all the input, guys. Sounds like what I suspected - the circuit breakers in the switch not up to the current draw of the halogen lights. I'll be grounded to daylight driving til I get a relay set up installed.

  15. Harry o
    Joined: Jan 19, 2012
    Posts: 200

    Harry o
    from Georgia

    Make sure the headlights are grounded ...

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