Change head light

Check the wiring on that light. Also check the bulb with a couple of wires to the battery, or swap the bulb left to right to make sure the new bulb is okay.

I DON'T KNOW. $1000 ASSEMBLIES ARE PROFIT MAKERS FOR DEALERS. I THINK ASSEMBLIES ARE JUST PLASTIC LIGHT SHADES AND NOT RELATED.
VISUALLY COMPARE PART NUMBER OR LOOK OF OLD BULBS WITH NEW BULBS. CHECK WITH CAR MANUAL.
WHAT IF THE LIGHT SWITCH OR RELAYS ARE FAULTY.?
AT NIGHT LOOK AT RUNNING LIGHTS. HAVE SOMEONE TURN ON LOW BEAMS.THEN HIGH BEAMS TO BE SURE.
YOU HAVE 3 LIGHT LEVELS. YOUR RUNNING LIGHTS AND HIGH BEAMS ARE WORKING BUT NOT YOUR LOW BEAMS. LOOK IN YOUR OWNERS MANUAL FOR THE HEAD LIGHT FUSES AND OR RELAYS TO SEE IF THERE ARE SEPARATE ONES FOR HIGH AND LOW BEAMS.

HEADLIGHT SWITCH

Check the light switch, fuse, relay and the wiring to the bulbs. Don't forget the ground wires either.

Check fuses, most vehicles have head light fuses for high & low or right & left, or you may have a connector problem at the bulb.

open your hood and it should be right behind where the light is you will have to twist it and pull it out there is only one light for the low/high beams

i would try replacing those bulbs,the headlights are dual filiment and can work on just high beam and not on low beam,so start there and replace your bulbs

Change the bulb. High and low beams are separate bulbs located in the headlight housing. Im not sure on the 07 but the earlier design Yukon (02)you have to pull out a pin located under the hood on the top of the light housing in order to remove it.

how to replace the high and low beam head light bulbs on my 2007 colorado?

If they work at night leave it alone
(Those ******* "Driving Lights" cost you gasoline to run.)