Headlights won't TURN off. Help!

Discussion in 'GM Electrical Tech' started by billetman, May 31, 2011.

  1. billetman

    billetman New Member

    Hey everyone.

    In my 99 silverado my headlights will not turn off. Daylight or night time they will not shut off. They will shut off if I apply the parking brake so I have eliminated that part of it.I have tried pushing the dome override button four times and that didn't make any difference. I recently got ahold of a manual and it does troubleshooting with a gm scanner tool. I dont have a scanner or access to one. I was wondering if anyone else has had this problem, and if so how was it fixed? I tore the dash apart today and didnt find any loose connections as I could see. Starting with the simple stuff. any suggestions of what maybe it would be? would be greatly appreicated.


  2. KyleZ71

    KyleZ71 Epic Member 5+ Years 500 Posts ROTM Winner

    You have tried using the little turn nob at the dome over-ride button right?
  3. Jimmeh

    Jimmeh Epic Member 5+ Years 500 Posts

    Dumb question, but is there something covering the little sensor on your dash? If there is something covering it, your headlights will automatically come on since it will think it's dark. Here is a picture from the outside of the truck of the sensor I am talking about in my dads 99 Silverado:


    I had a receipt covering the one in my truck and my lights were on constantly. And my old company truck I drove at my old job was missing that sensor completely, so the lights were constantly on. Just a thought.
    kennythewelder likes this.
  4. billetman

    billetman New Member

    kylez71, yeah ive tried the knob at the override button, didnt make any difference.
    jemmeh, theres nothing covering the sensor, I had the dash tore apart yesterday and I could see the wire that plugs into the sensor. It had a good connection from what I can see. I didnt get to carried away with taking the dash apart so I couldnt see where that wire lead to.

  5. 59diesel

    59diesel New Member

    Looking at your headlight issues. Did you ever figure it out? I have a 99 Sierra with the same issue. Soon as you turn on the key and start it, lights on day or night, and I CAN NOT figure it out. The DRL do not work at all, have good bulbs, sensor is hooked up, not covered with anything.....anyway, I know its been a while with yours but figured Id ask........
  6. loudpipes

    loudpipes New Member

    The lights do go out when you turn the key off don't they? I am experiencing same thing with mine. My Impala has the lights on in daytime also but can be turned off with override position.
  7. xPosTech

    xPosTech Epic Member 5+ Years 500 Posts

    I think I'd first check the relays controlling the lights. See if the relays have good inputs for ground and 12V (by good I mean 12V across coil when on and no voltage when off). More probable is stuck output contacts. Some relays that pull high current will actually weld the contacts together.

    If you find a relay that was just stuck and after messing with it seems to work, replace it. It will fail again.

  8. RayVoy

    RayVoy Rockstar 4 Years 5000 Posts

    Hey Ted, my first thought was a stuck relay, but that would keep them on all the time. These go on and off with the key.
    I'm leaning towards either daytime running being on, or maybe the ambient light sensor thinks it's always dark.
    OP, by any chance, do you have a hat, or book covering the dash mounted light sensor?

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