Headlight out, brake lights always on..related?
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Cadillac DTS Forum - 2006 through 2012 Discussion, Headlight out, brake lights always on..related? in Past Cadillac Vehicle Discussion; I have a lighting puzzle: I had a head light out. Trouble shot it to find it was the ballast. ...
  1. #1
    rbdts is offline Cadillac Owners Member
    Automobile(s): '08 STS '08 DTS
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    Headlight out, brake lights always on..related?

    I have a lighting puzzle:

    I had a head light out. Trouble shot it to find it was the ballast. I replaced the ballast and all was good, for just a few days. Now the headlight is out again, but I have also
    noticed that when the lights are on, the brake lights are always on. Additionally, the brake lights do NOT come on when the headlights are off. My thought is that because of the headlight not working, it is affecting the brake lights. Is this possible? Very puzzled...

    Thanks for any insight!

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    TopherS is offline Cadillac Owners Fanatic
    Automobile(s): '08 DTS LuxIII (70K mi.), '06 SRX V6-AWD (40K mi.)
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    Re: Headlight out, brake lights always on..related?

    I wish that I could give you better info, but have you tried resetting the electrical system? Disconnect the battery and then touch the postive and negative wires together to discharge all capacitors, etc. This seems to sort out many electrical gremlins. SuperJim has a perfect step-by-step on the proper order of things. Do a search for it. See if that helps with some/all of your electrical woes. Good luck.

  4. #3
    Superjim's Avatar
    Superjim is online now Cadillac Owners Connoisseur
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    Re: Headlight out, brake lights always on..related?

    There is a way to REBOOT all of the electronic modules in the entire car.
    Sometimes (lots of times) that will fix random electrical gremlins.

    Remove BOTH battery cables... negative cable FIRST...
    Touch both cables together for 5 seconds or so, making sure they have good contact with each other.
    This will drain all the capacitors in the system.

    While you have the cables off... undo the one bolted to the floor.
    Take a little piece of sandpaper and sand the paint away from the attachment point.
    It will then have a better ground.

    Re-attach the battery cables... negative cable LAST...
    You will have to do the window EXPRESS UP learn again and you MAY have to do the memory seat settings again.
    Sometimes they will forget the seat settings and sometimes they don't.

  5. #4
    rbdts is offline Cadillac Owners Member
    Automobile(s): '08 STS '08 DTS
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    Thread Starter
    Turns out it was simply the brake light switch sticking ...

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