Instrument Lights and Daytime Running Lights Not Working

[Double-A]

I am having a problem with my instrument lights and DRLs not working in my 1986 Chevy K20 Scottsdale. The original headlight switch connector is gone (previous owner thought he was an electrician) but the headlights work. And when I put the wires that don't work on the headlight post the DRLs work but the instrument lights still don't. I checked the fuse it's OK. But the fuse terminals are dead.

Hopefully you guys can help me,
Aaron

[Captkaos]

Day Time Running lights?  These trucks didn't have those...
What actually works?  The headlight and marker lights, no lights?

[Double-A]

The orange lights in the grille are the drls I've heard. Different names I guess. But at the moment only the headlights work. If I switch wires around on the headlight switch I can get the orange lights to work but that sacrifices the headlights. The brake lights and turn signals all work as do the high beams.

[Captkaos]

Those are parking lights.  Daytime running lights are white.
There is 2 positions on a factory headlamp switch.  1 click out is parking, all the way is all lights. 
Do the headlights work in both locations, or does it have nothing like the factory switch in it?

For all power both park and headlights will burn.

[Double-A]

It has a factory style switch. It was replaced by a previous owner. One click out does nothing.. No lights at all. All the way out just the headlights come on, no parking lights.

[Captkaos]

If 1 click out does not turn on the parking lamps you have it wired incorrectly.  That should turn on the parking lights (all lights except the headlights)

[bd]

A dead tail lamp fuse supply socket indicates loss of power into the fuse box.  Find the two-post junction block mounted to the firewall above the back of the engine.  Give the red wires (fusible links) connected to the junction block a tug to see if any of them stretch or pull apart.  Factory power routes directly from the firewall junction block, through a fusible link and bulkhead connector into the back of the fuse box.  The running lamps and instrument lamps are on the same circuit.

Use the 1986 Wiring Manual for reference.

[Double-A]

I have it wired up like the wiring diagram shows.

[bd]

Have you checked the fusible links and verified power through the firewall bulkhead connector?

[Double-A]

I haven't. I have the headlight switch wired like the diagram I have shows to. I can't really look at it any this weekend though.

[Double-A]

Also if my tail lights work wouldn't that mean the tail light fuse is OK?

[bd]

Also if my tail lights work wouldn't that mean the tail light fuse is OK?

In your original post you stated that, "the fuse terminals are dead."  Were you referring to the tail lamps fuse or the instrument lamps fuse or both?

[Double-A]

I was referring to the instrument panel light fuse

[bd]

Regarding the instrument lamps, make sure the headlamp switch knob is rotated completely CCW, just short of turning on the dome lamp. 

For the tail lamps to function, but not the front running lamps, implies a faulty connection through the firewall bulkhead plug or open in the brown wire that leads to the forward lamps.

[Double-A]

Ok. I'll have to go look at the firewall connector. The switch is rotated as you said when I test it. I'm pretty sure the brown wire is OK but I'll check that as well.