The O W Donald.
 

Working on finding the short in my upper brake lamp. '93 G20 W/high top. Access to the circuit in the rear easiest through a speaker cutout. OM Donald is printed on a cable (looks coaxial) running up to roof. No clue what this cable used to be for aa a previous owner also managed to take off the roof rack. Any ideas what it was for?
https://cimg2.ibsrv.net/gimg/chevrol...c55a54000b.jpg
https://cimg7.ibsrv.net/gimg/chevrol...3e872ec7d7.jpg
https://cimg0.ibsrv.net/gimg/chevrol...3ed8784236.jpg
Noticed the upper speakers in the 3rd picture also have no power.

TV antenna or satellite dish? CB radio?

Was thinking the same thing. Disconnected it since there's no life one the other side anyways. What I know from driving chevy. The CHMSL (Center high mount stop lamp is tied into the CC for diagnostic purposes in the late models. They hired OW Donald company to hook up the designer model. Emailed them in hopes they still have a wiring diagram for the speakers. Everything up there looks factory. My work in the dash has never had issues before. Wires for the lamp/speakers go down driver side between siding and fiberglass cap. Maybe service access under interior trim? Service manual does not have stereo system listed in diagram (can't find where the lamp ties into CC either). All other switches/lights/accessories besides CC/ABS work perfectly.
https://cimg3.ibsrv.net/gimg/chevrol...91c9cb8137.jpg
https://cimg2.ibsrv.net/gimg/chevrol...faaf5170e2.jpg
https://cimg2.ibsrv.net/gimg/chevrol...c100b67d5c.jpg
This plug up front.
https://cimg8.ibsrv.net/gimg/chevrol...fdf5fd2430.jpg

Gotta back out of it until next weekend as tomorrow is a hunt for the WSS at the local yard.

In custom vans of the day, it was not uncommon for the roof rack to actually BE an antenna, usually for TV, whether the van had a TV or not. Not sure why it would terminate with a BNC connector (at least that'e what it looks like).

Have not received any response from OW Donald yet, don't expect until tomorrow afternoon at the earliest. The original box tv and vcr setup is still installed and working. Can't test reception due to everything going digital though. Any ideas about the hanging plug though? I have a cb that's getting installed soon enough and the plug is too small for that application.

That's the curious part. Today's TVs use an F connector, but back in the day, it was flat 300 ohm cable, with simple screw tabs. CBs use a PL-259.

Wait. Are you sure the cable and connector go to the roof rack? Early cell phones use a TNC, which stands for "threaded" N connector, as opposed to a BNC, "bayonet" N connector. Is the outer ring threaded? If I could see it from the side I could tell.

https://cimg3.ibsrv.net/gimg/chevrol...dcb5bc6a7b.jpg
https://cimg4.ibsrv.net/gimg/chevrol...0a56d76cf6.jpg
https://cimg6.ibsrv.net/gimg/chevrol...634a01defc.jpg
Got me, lived through the era. Didn't know anyone with a car phone though. Grew up country.

One of my many jobs in my 60 years was radio communications installer, including the original UHF/VHF mobile phones, and the first cellular (installed) phones. It was at a time when CB was losing popularity. Prior to that, I installed car stereo and other aftermarket equipment, including CBs. It wasn't until the 90s that I got into Amateur Radio.

The top pic in your last post is an F connector, for TV, and the other is a TNC for installed cell phones.

Cool, thank you. Now at least I know were to install a digital antenna at if I chose to do so since that wiring is already there. Do you happen to know were the other end of the phone connection might terminate at? Don't see much use for it nowadays.

Typically the box was mounted under a front seat in a van.

That's a fiberglass roof, isn't it? The phone probably performed poorly if it is. A 1/4 wave antenna (most roof mount types) requires a metal "ground plane" which fiberglass doesn't have. If you're installing a CB antenna in the roof, you may want to consider putting a grounded layer of foil about 2 feet diameter, centered on the antenna. Otherwise, your SWRs will be high.