i got my amp installed from the stock TC headunit and one of the RCA cords don't work therefore i had to bridge my red RCA to power two of my subs. can anyone help me fix the the BLACK RCA cord? do i need to get the RCA cord replaced or is it just the headunit that could only take one rca?

 

Did you use a High-Low adapter? Make sure that's wired correctly. Next I would replace the RCA's , don't re-run them just drape them from the radio to amp and the re-run them if that's a fix. Just gotta check everything.

 

One of my RCA cables went bad when I was installing my amp. I got new cables, and problem solved. So I would focus on that and figure out if it was a bad RCA cable...