Break Light issue 1966 300

Electrical & Ignition

  1. Ralph Johnson

    Ralph Johnson New Member

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    I have just developed a break light issue that has me stumped on my 66 300. All the back lights on the right are functional. On the left all lights work expect the break lights. The left turn signal and lights work however the left break lights don't work. I tried replacing the bulbs but have the same results. Looking for some advise. I did down load the wiring diagram but haven't tried tracing wires back .


    Thanks for all the replies. I found the dark green wire that runs from the turn signal switch was pinched inside the steering column. It was caught between the column and the cancelling unit.
     
    Last edited: Nov 4, 2019
  2. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    The brake lights are wired thru the turn signal switch, most likely there is a problem with your turn signal switch since the brake lights and turn signals use a common wire once the circuit is past the turn signal switch.

    Dave
     
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  3. Lefty71

    Lefty71 Member

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    Brake light switch (by the pedal) operating correctly?? Nevermind, i guess you are saying the problem only occurs on the left side, right side works fine??
     
  4. bluefury361

    bluefury361 Old Man with a Hat

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    The turn signal switch feeds the brake light switch. If one side is working then it should be ok. If the other lighting works on the left rear then the ground is ok. The left rear also feeds the right rear. My guess is a open circuit, (cut or broken wire) feeding the left bulbs beyond the right side split.
     
    Last edited: Nov 4, 2019
  5. Gerald Morris

    Gerald Morris Well-Known Member

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    Check voltage on each wire on your left rear lights. Get a pal to press the brakes for you or improvise some other means of closing the brake light switch. I suspect your trouble resides in the trunk on the left side. I get these problems ever so often, and usually can re-seat or rewire the malfunctioning member sans difficulty.....
     
  6. Ralph Johnson

    Ralph Johnson New Member

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    Thanks it turned out that a wire was caught between the turn signal cancelling unit and steering column.
     
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  7. Ralph Johnson

    Ralph Johnson New Member

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    Thanks for everyone's help.
     
  8. WSP

    WSP New Member

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    My 68 had exactly same problem. Broken wire at turn signal. But since the turn signal canceling cams were broken anyway, I am replacing the whole unit and harness with a repop.