Make low beams stay on with high beams.
Haven't seen any threads about this so I thought I would throw in my two cents. Some years ago, GM engineers decided to wire Chevy pickups so when the driver turned on the high beams, the low beams go off. This doesn't make sense to me so I came up with a fix.
I started by calling Painless wiring. I asked if they made anything for the Colly with 4 headlights that would make the low beams stay on with the high beams. The tech rep talked to his engineers and was told that the kit for late model Silverados would work.
So I bought the kit (high beam relay) from Jegs, installed it and it didn't work. The low beams still turned off when the highs came on. I called Painless back; I told the tech rep what happened and got him to email a wiring schematic for the front headlights on the 05 Colorado.
After looking at the schematic, I came up with a fix. All four headlights have power to them all the time. A relay controls the ground circuits. When the lows are on, the ground is taken away from the high beams and vice versa.
I didn't post pictures because the fix is simple.
Remove the grille and unbolt the headlight assemblies. The headlights use two 10mm bolts.
Remove the wiring harnesses from the back of the headlights and set them out of the way.
Do one side a a time.
Take the harness for the low beam and unwrap the factory electrical tape so you can see the two wires. On my 05 Colorado Z71, the "hot" wire is "orange" and the "ground" wire is "dark blue".
Splice into the dark blue wire using a Quick connector and 12 - 18 inches of wire (use 18 ga or heavier wire).
Attach the other end of the wire to a good ground, (I drilled a small hole in the sheet metal behaind where the headlight assembly mounts).
I used an electrical connector, sheet metal screw, and two star washers.
The hardware store calls them "shakeproof" washers. They keep the screw tight and help make a good ground.
Wrap some new tape around the wires where they come out of the plastic loom.
Add a ground wire to the other low beam harness in the same way.
Reinstall the headlights, don't forget to plug the harnesses in (I did this, LOL).
Reinstall the grille and you are done!
Now the low beams will stay on when the high beams are turned on. It makes a big difference when driving backroads in deer country.
I also replaced the headlight bulbs with Silverstars. I get flashed alot at night because other drivers think my high beams are on. Then I turn on the high beams and give em all four lights. (I know, I know, but it's fun).
2005 Z71 LS Crew Cab 4X4 L52, 4L60E, GT4, Silver Birch Metallic
Waiting for the Baby Duramax.