I have a 94 Dakota with an aftermarket JVC headunit and roadmaster speakers all around (cheap I know). I also have a 10" Memphis PR sub powered by a Lightning Audio 250 w amp. The problem is with the speakers. With the engine off, everything is fine, however when I start to drive around the speakers will fade all the way out eventually. When I come to a stop they will fade back in, bat as soon as I let off the brake pedal, they fade out again.
check your wiring. ground points for amplifier and head unit line from battery to amplifier (direct not through a fuse box in the glove compartment) remote trigger for amplifier
I have checked and double checked the wiring. The headunit is grounded directly to the battery. The strange this is, when the speakers fade out, the sub does not fade.