How exactly do the auto-headlamps work? My thought was they turn on automatically when you start the vehicle, and turn off 20 seconds after the vehicle is turned off. But I have noticed that the headlights do not ALWAYS turn on when I start the vehicle. Is there some type of sensor that tell them not to turn on if it is sunny, or even this morning when the sun was just coming up... Is this something I should have the dealer look at?

 

Auto-lamps on '99-02(?) models have an adjustment screw on the controller that allows you to shorten or lengthen the ammount of time the lamp remain lit after shutting off the truck. I believe this was eliminated in 02 or 03.

The lamps (if they aren't DRL) will not light if the photocell on the dash is recieving enough outside light to indicate "the sun is up". Can't help you with the location of the photocell, AutoLamp wasn't a feature in my year.

Hope this helps.

 

That is more information than I had. I didn't see a photocell, but I will check again and see. I could have sworn that the headlights came on during the day as well though...

 

The sensor is located under the oval shaped dash cover. You will see slots on the left side of the cover; that is where the sensor "sees" the outside light levels.

I added this to my '01 'Screw. In my truck, the lights DO NOT come on at all if it is "daytime". However, early morning or dusk they sometimes come on, only to turn themselves off 30 seconds later.

I think it errs on the side of caution and then decides on the light level outside after a few seconds go by.

 

B-MAN is correct! The sensor is located in the dash under that little slotted area. No they do not come on during the day. If you have lights that come on during the day, they are daytime running lights (DRL's). These only run at about 80% of the 12v power.