Daytime Running Lights / Headlights - Same Brightness

Discussion in 'GM Electrical Tech' started by TXExpat, Jul 25, 2011.

  1. TXExpat

    TXExpat New Member

    So when i was aligning the headlights on my 1997 C1500 last night I discovered a new issue. The DRLs and headlights are the same level of brightness. I can't say for certain but I'm guessing that the headlights are the DRL brightness. They don't look all that bright but I guess it could be the other way around; I'm not certain how to even check which light output is correct.

    Anyone have any idea where I should even start looking for the problem? I just replaced both headlight housings because the original ones were weathered and didn't allow the headlights to throw much light. Obviously I think this issue may have made it even worse, but I'm fairly certain that this problem existed before I switched housings. The headlight switch itself is working properly, it will turn on the marker lights in the middle position and brings the sidelights on when put into headlight position.
  2. Ethan

    Ethan Rockstar 100 Posts

    Did you put 4 of the same bulbs in? The outside bulbs are your low beam, and the inside bulbs are your high beam, so it's two different bulbs in each housing.
  3. TXExpat

    TXExpat New Member

    Nope, it has two different bulbs.

    TELORVEHC Rockstar 4 Years 1000 Posts

    How old are your bulbs? Also, make sure your headlight wires are making good connection and aren't loose, damaged or frayed.
  5. stephan

    stephan Rockstar 4 Years 5000 Posts

    I'm guessing that the HLs are down to the brightness level of the DRLs rather than the DRLs being too bright. This could be a loose or bad ground connection (HL circuit) cuz it will cause high resistance & cause the lights to be dim.
  6. TXExpat

    TXExpat New Member

    Hmmm. Ok. I'll see if I can do some investigation on the HL circuit grounding and see if I turn anything up. I'm also going to see if I can disable the DRL module and see if that makes any difference. The bulbs are all new and I did give the connectors and wires a once over before I buttoned everything back up.
  7. Revredneck

    Revredneck Rockstar 100 Posts

    If you set the parking brake with the ignition on, it should turn of the DRL's. That's a quick test of the system. There is a relay in the underhood fuse and relay box that can cause problems with the headlamps. I agree with those who say you should also check for a good ground for your headlamps. Sorry, I don't know the exact location of that ground, but you should check on the radiator support and be sure the battery to body ground is good.
    Good Luck and God Bless
  8. TXExpat

    TXExpat New Member

    I was out of town for a while so I didn't have time to mess with the lights but I do know the DRLs do shut off when the e-brake is engaged. I'll see if I can track down the ground location this weekend and see if that provides any clues.

    Thanks for all the advice, I appreciate it!

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