Interior light mystery

[inkslinger]

1983 c20. Interior lights.
Working dome light when using door buttons. Doesn’t work when turn light switch all the way to left with doors closed.
Courtesy light not working. In the pics below ther are two orange wires coming out of courtesy light. Where do the go.
I believe I found one but not the other.
In the other pic is a complete loom from an 84. It has a connector on it but not sure what it connects to.
3rd pic is a broken orange line from fuse box.
Thoughts

 

[Grit dog]

I’d look at the wiring diagram and go from there.

 

[fast 99]

Keep in mind power is standing on the dome light. Headlight and door switches close the circuit.

 

[RustyPile]

This topic was thoroughly covered in a thread just last week.. Before you get started, you'll need two special tools.. #1 - a wiring diagram for your truck. #2 - a 12 volt test light or digital voltmeter..

Here's a link to that thread:

Cargo and Dome not working

The cargo and dome lights haven't worked in the C20 since it's been parked in the garage, so I ordered new bulbs for them from LMC, and installed them hoping for the best, but no joy. Courtesy fuse looks good as its a glass fuse and it'd be easy to see. I've checked all the connections and can't...

www.gmsquarebody.com

 

[75gmck25]

To add to Fast 99’s explanation, the dome light circuit works differently than other circuits in the truck. It has constant power, and the ground is switched.
- Orange wire always has power for the dome lights, truck bed light, etc.
- white wire is the ground for the circuit. The door switches will ground the white wire to the body, or you can ground it by turning the headlight switch far left, past the detent.

Because of this design, all the interior light housings are isolated from the body so they don’t ground and turn the light on. Each light has two wires on it can connect to both power and ground. This is different than other lights in the truck, which are usually grounded directly to the body, and then the power is switched.