Interior accessory electrical problems

[Lustle]

Hey everybody,

I'll start by saying that I'm new to the forum. And new to GMC ownership. I've got myself a 1987 GMC R1500. Daily driver/project truck. I've got a few things on the way. Powder coat flat black 15x8 rally rims and new BF goodrich radial ta tires should be this week. Maybe some new 2" inch beauty rings in stainless.

As for now though. I have one problem I can't seem to figure out. In the interior. My dome light doesn't work. My horn doesn't work. And my aftermarket head unit resets every time I shut off the electrical, but still runs with the key turned. The cigarette lighter doesn't work. I've checked the bulb on the dome, its fine. Usually these things are on the same circuit aren't they? I've checked fuses. They are fine as well.

Any ideas? Anyone come across this before? Maybe just a ground that needs to be hooked up?

If this is somewhere else on the forum I apologize. I tried searching. I've seen people with the horn out. Or dome light out. But never all the accessories.

Thanks for any help.