Car Stereos: Spec V Stock Rockford Fosgate HU problem, factory wiring harness, rockford fosgate

Question
Hello,
 I recently tried wiring an after market amp to the factory wiring harness that originally lead to the factory sub (blew the sub, tried to replace). I have the amp and the power/remote wiring very secure and grounded. The RCA's from the aftermarket amp, I cut and spliced the positive to the sub wiring harness and the speakers played fine at a low volume. When I turned it up, it blew the fuse (didn't have the negative connected because it put the amp into protection mode. After a few attempts, I decided to unhook the amp and try it again in a week or so when I get more free time. After uninstalling all the wiring that lead to the wiring harness of the factory head unit, I now have a fuse-related problem. I checked all the wiring I touched or spliced and found no continuity problems.

My question is this: The Rockford Fosgate package that comes with the Sentra Spec V has no output power (0-watts). It gets all it's power for all 9 speakers from the factory amp in the trunk. Everytime I turn on my head unit now, it blows the 20A "mini-ATD" Electrical Fuse under the hood. I replaced the fuse, and same thing, when I turn on the head unit, it blows the fuse again. What could be the cause of this?

Answer
Hi Alex.

it could be due to internal damage on the amplifier, somehow you managed to burn the electrical components and now they are shorting out, just to make sure bench test the amplifier and if the problem  duplicates then you have found the problem.

Regards.

Ed.