The car is a 92 Convertible Trans Am. The passenger rear speaker has never worked. I replaced the factory head unit with an Alpine...... no dice. I replaced the factory rear speakers....... no dice. My question is are there any other connections between the head unit and the rear speakers, aside from the factory connectors to the deck and rear speakers.

 

According to my manual for the 92 firebird, the rear speaker wires are a straight shot from the head unit to the speaker. The wires for the right rear speaker are dark blue to pin "B" of the speaker and light blue to pin "A".

 

Did you check at the actual speaker? Did you use a harness when you put in the new head unit? If you did, were there any stray wires that maybe fell out of the old stock harness?

 

I used a harness for the deck and just cut the factory speaker connectors off. If its a straight shot from deck to speaker I guess one or both would have had to of fallen out, I think I would have noticed though

 

Another thing to keep in mind is that the previous owner may have done something, or GM did something screwey with your wiring. I know that it is a straight shot from the deck to the speakers, but in my car, the wire coloring behind the deck is different than the color at the actual speaker. This leads me to believe that they are spliced together someplace. Did you pay attention to color when you did your installs?

Anyway, I would just recommend getting some of your own wire and running it from upfront to your speaker that isn't working. It will probably be higher qaulity wire anyway. Its really not that hard to do either. Just run it like you would run wiring for an amp and sub set up, and be glad you are doing it on an F-body