I recently reinstalled my subs and amp into my car, but since the installation they have been acting up. When ever i turn the key, and the amp turns on, the subs do a quite low buzz, and when i turn on headlights they pulse, and when I'm driving you can hear it get louder while accelerating. I have to go pick up another radio harness, because mine is having issues, and wasn't sure whether or not the harness was the issue, or something else.
Thanks,

Pioneer head unit?

No, I am running an alpine head unit.

sounds like a possible grounding issue, is the amp grounded securely to a spot where the paint has been scraped off? tight solid connection. same goes for the headunit. does it make any sounds similar thru the other speakers? if its just the sub doing it, its likely the ground with your amp or your signale out of the headunit.

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Make sure the RCAs are fully inserted.

sounds like a ground loop... ground amp and h/u to bare metal with a bolt as was stated before..