Headlight issues!!!

[a7x4life2005]

I recently bought a 2001 Yukon XL and didn't know it at first, but it has headlights issues!

My Yukon had projector beams installed before I bought it. And, for some reason my high beams stay on all the time but are EXTREMELY DIM until I click the high beams on and only the RHS becomes bright while the projectors and LHS high beam goes completely out until I click high beams off and they both go back to being dim again.

I was thinking it may be an issue with the projectors, so I put stock headlights back in it and completely did away with the entire projector set up. No difference at all. Both low beam and high beam are still staying on together very dim.

So, I called up the guy I got it from and he said he put in the projectors himself and that's when the issues started. He played "none the wiser" after that.

Should I be checking the headlight switch, underhood relay, splices in wiring, dirty/corroded plugs, bad/loose/broken grounds etc.. or?

ANY help at all on this would be much appreciated!!!:emotions122:

[ezdaar]

look for a 4 high mod,
Check bulbs, obvious, but gotta say it..

If worst comes to worst, a DDM Relay harness will fix ya up.
Buy 2 of them, hook one to a known good low beam plug and the other to a known good high beam.
Tadaa! problem solved...

[chauncey0337]

Sounds like a 4 hi mod gone bad.

[DenaliAK]

Ditto what the guys said.

Look under the hood in the fuse box. If there are little "wires" (diodes) connecting fuses oddly, someone probably tried the 4-high mod and messed something up. Yank those little wires out and then try the lights and see how they work.

That's the first thing I'd check for, anyway. Sounds pretty messed up, but could be really easy to fix if that's the problem.

[a7x4life2005]

Just checked the fusebox and there were no jumpers. Also, I read a tech write up on a 4hi mod on here about adding or "splicing" in a ground to the low beams and didn't find anything of the sort.

Although, while checking all my plugs and wiring, I noticed that the plugs for the high beam on both sides are spliced in to and feeding the wires for the DRL on both sides. Starting to think the P.O. has the light wiring all jacked up!

So I know it's done right, would I be better off just rewiring the DRL, high and low beams from the fuse box back or would it be much more simple spending $30 for a couple DDM Relay Harness' as mentioned above and going that route. And also, going with the harness, would that do away with the jacked up splices?

And again, thanks to everyone for their time on this!!!

[GeneralNoobzor]

I would go with the DDM, make your lights much brighter. :)

[chauncey0337]

I would go with the DDM, make your lights much brighter. :)

Just checked the fusebox and there were no jumpers. Also, I read a tech write up on a 4hi mod on here about adding or "splicing" in a ground to the low beams and didn't find anything of the sort.

Although, while checking all my plugs and wiring, I noticed that the plugs for the high beam on both sides are spliced in to and feeding the wires for the DRL on both sides. Starting to think the P.O. has the light wiring all jacked up!

So I know it's done right, would I be better off just rewiring the DRL, high and low beams from the fuse box back or would it be much more simple spending $30 for a couple DDM Relay Harness' as mentioned above and going that route. And also, going with the harness, would that do away with the jacked up splices?

And again, thanks to everyone for their time on this!!!

Can you locate the original drl harness? If not, I would just rewire the drls and see if that works. No need in buying and installing unnecessary relays, imo, unless you're upgrading to hids.