I got everything I need to install the sub and amp in my 08 expedition limited I'm gonna keep the factory head unit gonna use a hi/low converter. But tried to find out buy looking online what the four wires coming out of the factory amp are. Also is down the passanger side the best way to go for the power wire.
Are you talking about the wires coming out of the head unit or the amp mounted to factory sub enclosure ???
The four wires coming "out" of the amp ( black and white wires ? heading toward subwoofer ) should be two positives and two negatives as the factory sub is dual voice coil.
As for the wires coming from back of head unit toward amplifier ....
Violet/Green = Sub +
Green/ White = Sub -
Orange = Sub Shield
Violet/Red = Sub Enable ( Amp turn on )
At the amp there should be two additional wires...
Black/Blue = Ground
Brown/Red = Power
Matt