On lunch break I checked all of the speaker wires with an OHM meter.

BOTH left speakers are shorted to GROUND, so it's definitely something that was done at the body shop and not just coincidence...

For the heck of it, I snipped both LEFT + speaker wires and tried radio again with both shorted speakers out of the mix....

still didn't work.

I guess they have to at least be connected to complete the circuit?

I plan to drop it off at the body shop Saturday and let him see what he did wrong...either that, or just say EFF IT and get a new aftermarket head unit, some real speakers, and all new wiring, lol

 

Did you check behind your glove box for an amp? That amp fuse is for a separate bose amp, iirc and wouldn't necessarily be for the factory amp on some trucks. The radio doesn't need speakers to "complete a circuit" the radio's amp is going to output voltage regardless of whether there's a load or not. When you unplug your factory radio are there 2 plugs, or just 1? if there are 2 and you don't have a separate tape deck mounted in a console, then you have a separate amplifier.

 

Thanks for the reply.
There are two harnesses that plug into the rear of the factory head unit, and it does have a separate factory cassette deck mounted down below the dash mounted radio. The smaller of the two harnesses also looks to have another harness plugged into it. I attached pics

If that smaller harness on the left is just for the cassette deck, maybe I should try unplugging it??

 

ok, check the resistance on the speaker wires in your harness, and make sure they're reading somewhere around 4 ohms...or you can just have the body shop figure it out.

LF - Tan+ grey-
RF - Light green+ dark green-
LR - Brown+ yellow-
RR - Dark blue+ Light blue-

 

After work I used a continuity tester and found continuity between the yellow and brown wires and the truck's ground....I ended up yanking off the sill plate and rear door panel...again. Tugged on wires and found that they were pinched and shorted to ground by the lower seat belt bolt...

Thanks for all the ideas and replies guys. I appreciate it a lot! I am so relieved now but I am still going to order new rear speakers, an Alpine head unit and an Alpine amp, now that I know the problem is solved.

I know the body shop guy is happy too....lol

 

glad it was an easy fix.