Auto headlights on 01 GMC?
 

Hi guys new here, and new to GMC trucks Ive always had older fords and a couple of dodges.

My question for today is (I will have many many more)

I just picked up a 2001 GMC Sierra SLT 1500 extended cab short bed 4x4. The thing I am wondering about is, my headlight switch does not have a auto mode, but quite often my headlights turn on when I turn on the key. Are my headlights shorting out? Or is there a light adjuster switch or something that turns them on when it gets darker out? Also, my running lights never work. I put in new bulbs and no blown fuses. Any ideas? Highbeam/lowbeams work fine, including when I dont turn on the switch.

Thanks for the help

That's just it, on these trucks, the lights you see when you turn the key forward is your day time running lights, not your headlights. The DRLs use the headlight bulb, but they act differently. The headlights, which you can turn on with the switch, illuminate the dash and turn on the marker lights.

I don't get why they did it that way, but they did ... hope this helps.

No, this truck has seperate running lights. My dads chevy has the lights like you are talking about. When his are on his tail lights are not on, and they turn on every time he turns on the key. Mine do not turn on every time i turn on the key, but when they do, the tail lights come on, and i can switch between highbeam and low beam just like normal

I finally figured it out. the truck does have a light sensor to turn on the headlights when it gets dark out, and as for the mini running lights, I did get those working but I forgot how i did it.