check signal input, maybe its the RCA, or your subwoofer polarity, if you have 2 or more subs, check your wirings, maybe there is something bad connection, some amp will turn on even if the remote turn on and ground connected, no possitive main from the battery,.. here is the quickest way, from your head unit, is there a signal output, to the RCA, are the connection are perfect?, amplifier input and output, is there a signal, do you have a good current supply? is the subwoofer connected?, your polarity, are they ok, subwoofer can't produce sound if they are not in the same polarity..