Headlights don't turn on. on 1991 GMC Sonoma

I can't seem to find a short, the fuse is fine, both headlights are fairly new, the switch seems to have power and works, the dash lights work fine, dome light works good, tail lights/signals/brake lights all work.

The guy who worked on my truck said they were working this morning and the night before. He is frustrated as to why they stopped working.

Underneath the steering wheel, where the fuse box is, I noticed a hokey setup to allow the brake light to turn off when not in use. Could it be possible there is something similar for the headlights?

Asked by for the 1991 GMC Sonoma
The brake switch you mention to turn them off is not factory and is very possible someone put one in line with the headlights as well. Do you have 12VDC at headlight bulb connectors? A wiring short would cause the fuse to blow if the short was on the power side and they would work if it was on the ground side. Check for the proper voltage then trace the problem back to switch since you say thats ok.
I found this on the internet, someone that had a similar problem. If you have experience using an electrical meter give it a try. You will also need a jumper wire as you will see in the link as well. Heres the link
Sorry for the late reply, but I had a chance to check what I could before it started to rain on me.

Here is what I had time to look at. I see 2 electrical blade connectors just hanging around. One on a yellow wire, the other on a white wire. There is also some sort of plug in adapter just hanging around. To further clarify, the area I am speaking of, is just behind the old OBD connector.

If the weather permits, I'll get my meter out and check out your link to see what else comes of this. I'll reply back to let you and anyone else, know what came of this.

Thanks for the tips.