2007 Tahoe LTZ, headlights won't turn off!!

[AndieAnderson]

Hello, I have a 2007 Chevy Tahoe LTZ and I'm having electrical issues; my headlights won't turn off! I've looked at everything, but they will not turn off unless I unhook the battery. I've seen several other posts, but it seems they've done mods of some sort, ant that is not my case. They only thing I've done is had an iPod hooky uppy thing installed (professionally) and that's been there since I've owned the truck. I've checked the battery cables (all 5) and they are moderately corroded, however the contact points are clean. Changed the fuse from the battery that's located on the firewall, and cleaned the terminal lugs. Before I spend $385 on all new cables, I wanted to check here to see if one of you knew something I don't. Nothing has changed prior to this problem starting. Any suggestions on where to start my troubleshooting are greatlly appreciated. Please help me!! Back on two wheels until I figure out what's wrong with my Hoe. Thanks in advance!

 

[Dahlar]

Have you tested the headlight switch?

 

[iCalvin]

It can be your switch going bad, as already mentioned, or your headlight relay is stuck on. The headlight relay should be located in the underwood fuse box. Either whack it a couple times to see if it is stuck or swap it with another relay and test.

 

[AndieAnderson]

@ Dahlar, not yet; pulling the dash apart as soon as I'm done here. @iCalvin, I didn't see a "relay" switch in there, just the fuses and I've checked those, but am looking again here in a sec. Thanks for the point in the right direction.

What's weird, is that the switch still works according to the dash but my DRL's aren't coming on either...

More once I get my hands dirty! Thanks for the tip!!

---------- Post added at 12:04 PM ---------- Previous post was at 10:13 AM ----------

Ok, so I'm not 100% sure what the relay looks like, tried googling it, but don't seem to have anything under the hood that matches in appearance.

However, I pulled the entire underhood fuse block up, checked the connections underneath, and low and behold, once reinstalled everything worked as advertised! Then when cycling the light switch, I could hear and feel the grey boxes listed as the PRK LAMP and HDLP LO/HID clicking. I'm assuming that these are the relays...

Now for replacing these, do they just pull up and out like the fuses? Or is there some special way of getting them out?

Thanks for the assistance! I did not want to just throw money at the dealership for them to troubleshoot my entire electrical system. The first dealer I asked for assistance, never even looked in that fuse box, and told me to bring it in on Tuesday...

---------- Post added at 01:53 PM ---------- Previous post was at 12:04 PM ----------

So I replaced the relay, for good measure, everything was working fine, then I got home, and the problem is back! Unseated the underhood fuse block, lights went out. Reinstalled, no lights, good right? Nope, as soon as I snapped the cover back on, lights are back on. My thoughts are now that, there is a problem with the fuse block or the contacts it's making beneath. Any suggestions??

 

[iCalvin]

Hmm that is kind of weird. Worst case scenario I can think of is that you have a short somewhere and is grouding out the lights causing them to turn on. This is just a guess but can be a possibility. There is also still the possibility your switch is dying.

Also, check the connections for oxidation (white powdery stuff.) I had my rear door speaker always come on and off due to oxidation in the terminals. Though oxidized or not it shouldn't keep your lights on with truck off.