Is the Headlight switch for the Chevy Express 2500 defective

Check the headlight switch to see if it is getting power from the battery.

https://www.youtube.com/watch?v=Mqk3cQAci3w
Should be similar to the Tahoe

I loo9ked up owners manual for 04 chevy express van. Just want to add, use clean gloves, don't touch bulbs with bare hands. Just my opinion.

Open the hood. Look directly behind the head light assembly. There will be two bolts or two metal/plastic tabs that you have to pull up on. Most likely tabs. One could be hidden under the radiator cover. Pull out on the assembly, if something is still holding it, it is just pop out tabs. pull straight out. Twist out the socket and install in reverse order.

Either the headlight relay is stuck on, or the security system's headlight control is shorted and keeping the headlight relay on. Find the headlight relay (probably in a fuse and relay box under the hood), remove it and check the contacts with an ohmmeter. They should read open in a good relay, but will read little or no resistance if the contacts have welded together ( a possible result of rapid on-off cycling).

check the shell earth wires in engine bay there are a few just look for them and check them and clean them up.

Check the headlight switch. The flash is not linked to the switch.

Well I don't see a fuse or fuseable link for the headlight circuit.
In years past there was a circuit breaker built into the headlight switch for the headlights and fuses for everything else.
I would check the red wire on the switch for power first.
It could also be a problem with the dimmer switch.

Dome light issues with Chevrolet Express van. Easy Fix
To the right of the headlight switch/knob, there is a square plastic base for the "dimmer" It has a post-like button in the center .. above the post is a switch - it doesn't look like one (it reads "Dome Off"). Press it in, and the interrior lights will come on when the doors open, etc. I just had my van serviced, and had to do this myself.



Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/keith_f374b1cfd1696a17

it is either a defective switch or a stuck relay. the first thing that I would do would be to replace the relay and then check it. If it still stays on then you have to replace the headlight switch.

here is a link to a repair guide for your vehice that will help you with the headlights along with any other thing you might need.
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800b4a31