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Headlights always on/No Daytime Running Lights (DRL)

SnowDrift

SnowDrift

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When I turn on the ignition, the headlights automatically come on, no matter how light it is and do not go out. The DRLs don't seem to work - they've not worked since I've owned the truck, in fact. The DRL fuse in the box on the fenderwell has power on both sides, but the headlights don't kick off unless I use the dome light switch, by pushing 4 times. I've replaced the dash sensor with an OEM part. What else could I check on this 2001 Sierra 2500HD?
 
Check to make sure that the parking brake is all the way up and not pushed in a little. It could be that the sensor that the parking break hits is stuck closed.

When working right you can push the parking brake down a click or two and the daytime running lights will go off
 
I'll check into this, Jaryd. I use the parking brake often and never checked to see if anything with it changed the situation. Is that about the only other place in the system that could be checked?
 
That’s the only thing that I know of that’ll cut the daytime running lights off.

I don’t know what the sensor looks like. I have never looked for it
 
The sensor is the little black semi-sphere on the dash top about middle of the dash.

I have no clue if it does go through bcm or just a relay. I had a few GM’s with them and never had a problem. I really do think the headlights run on a relay though, that’s why it was my theory to look for one (under the hood on drivers fenderwell).
 
Will L. said:
The sensor is the little black semi-sphere on the dash top about middle of the dash.

I have no clue if it does go through bcm or just a relay. I had a few GM’s with them and never had a problem. I really do think the headlights run on a relay though, that’s why it was my theory to look for one (under the hood on drivers fenderwell).
Click to expand...
I did find the relay. I guess I could swap it out with one of the others with the same P/N. I believe the A/C uses the same number.
 
On the note about the switch at the parking brake, if the light is on for the light indicator on the dash, is that reason enough to believe the switch could be working properly?

My other thought was that something has to signal the lights to function, but I would guess the signal goes from the switch to the dash light and also to what powers the headlights at the same time, separately.
 
If you swapped the relay with a known good one that is exactly the same type and it doesn’t work -check that the a/c or what ever you swap it with now works with the old relay from the light circuit. This is important incase the light circuit is blowing the relays.

Beyond this- really need a schematic.
 
SnowDrift said:
On the note about the switch at the parking brake, if the light is on for the light indicator on the dash, is that reason enough to believe the switch could be working properly?

My other thought was that something has to signal the lights to function, but I would guess the signal goes from the switch to the dash light and also to what powers the headlights at the same time, separately.
Click to expand...

Im pretty sure that the light indicator goes out when you push the parking brake down and the daytime running lights go out. Im with you thinking that if the light is on in the dash then the parking brake switch
is working right.
 
Someone suggested to me that if the sockets are burned up, which is a known issue with these trucks, it could cause the headlights to no longer turn off. Safety feature? Again, a schematic would tell the story, but I'm not sure my sockets are burned up.
 
I wondered if it would be a safety feature, whereas, if the DRL circuit is interrupted, then the headlight circuit defaults to always on. I'm just grasping at straws. The headlight circuit is independent of the other lights as a safety feature, so this is why it crossed my mind. DRL is would be an "extra" in my mind, but to some, it may be considered an essential safety feature?
 
If you still need schematics. I’ve got the 97 version scanned for DRL specific and Exterior lighting. They’re pretty spot on for my 96 and may work for you. Unfortunately, too large to post here. PM an email and I shoot them to you.
 
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