I want to say thanks for reading all this and helping out! So I am helping my friend with an 83 Z28 to work out all the seemingly small issues.

First we came across the first problem when trying to install a CD player where there was none since he bought it. Wired it all up using Haynes manual wiring diagram and nothing. I whip out the voltometer and see that neither the constant power wire (yellow) or the ACC power (orange) are getting power across them. I check out the radio fuse, fine. The fuse that is connected to the orange wire is a 30A fuse that controls whether the interior lights come on, which has been blown since hes had the car and continuously blows immediately anytime its replaced. I came to the conclusion that they are connected because I can stick one lead in the fuse holder for that fuse and touch the orange wire and get a continuity signal, unless they are both grounded at that point for some reason?

I found a wire jammed in the ECM fuse and it leads to a wiring harness that is also tapped off the two brake signal wires and the other end connects to the turn signal lever in the steering column and also through the firewall to a box labeled only with a serial number and description for adjustment screws to include: low speed adj, sens adj and cent adj. It also says somethin about transmission selection. The box is mounted by the horn on the drivers side fender. Once on this side of the firewall wires split up and some disappear behind the engine. Also from this box comes a throttle cable going to the throttle body. It also reads "DANA Corp.", the only reference I can find to DANA and camaros is a dealership called DANA that made performance 1st gen camaros, somewhat comparable to what Shelby did to mustangs. Im assuming its an aftermarket cruise control?
By the box there is 2 plugs just laying there that trace back to under the steering column on the engine bay side of the firewall. One is just a ground wire, no idea what the other one is, any ideas? They look like they might plug into something factory that is no longer there.

It all comes down to; any idea why this 30A fuse is blowing and why it controls the interior lights when the manual says its the ACC power wire? What is this seemingly OEM box that has quite obviously aftermarket wiring involved? what are the 2 plugs just hanging around supposed to be connected to?

 

The 30 Amp fuse is blowing because its shorted out. Does it only blow when the key is only on or does it blow at any time no matter what position the key is in?

 

I know the basic idea of why its blowing, I guess I was just asking where to start. It blows no matter what position the key is in. Like I said, the 30A fuse is on the circuit for the dome lights. Why am I getting continuity with the ACC wire? Would it be because possibly the dome lighting circuit is grounded out somewhere causing the fuse to blow and the same time being effectively on the same circuit (ground) as the ACC wire when the key is out (grounded). hmm....

but the only places that the wiring goes for the interior lighting is the only two lights by your feet on the drivers and passenger side right? Once they came on for a split second but the fuse blew again.

 

hey did you ever figure out what the boc labeled dana corp was?

 

*box