Hi i hooked up a scar audio 12 inch sub in my car. I hooked it up to the speakers using speaker imputs in a planet audio amp since i couldnt find a scar one with speaker imputs. But i used the speaker imputs since i didnt put a new head unit in. And it works perfectly when i just turn the ignition on. But as soon as i turn the car completely on the sub starts pulsing for like a minute then stops. I know its not the amp or the sub because i swapped out a different sub and amp from another vehicle that works perfectly and it has the same problem. Do you guys have any idea what my problem could be?