Well, thats power acoustic for you. They are not the most reputable brand. Like i said before you might need to use a switch. In the manual it "should" tell you the sequence. Nope, never mind it does not. I just looked at it. Try getting just a two-wire toggle switch. Hook up one side to ground and the other to the parking brake wire. It may have to see no ground when you first turn it on and then ground. Try ungrounding the wire, turn the unit on, play a dvd and then ground the wire. In some cases it has to see the no ground and ground sequence three times. It is a pain in the a$$. Try these things. Hopefully this helps.