The remote wire will tell your amplifier to turn on whenever the stereo is powered up usually whenever the vehicle is turned on. The cheap and easy way is to run the amplifiers remote terminal off of a switched accessory wire.
Car Amp Install 4 Steps Instructables
Where to run remote wire for amp. Youll have to remove the stereo to get to this wire. It is only powered when the key is in the accessory or run position of the ignition switch. On aftermarket stereos its usually a blue and white wire. To connect wire to wire an appropriately sized butt connector or other style connector can be used. The turn on wire also called the remote wire is located behind the stereo. This is the wire that your head unit uses.
On most vehicles the wires run to the glove box on the opposite side of the engine. Use a small knife to poke a hole right next to the opening where all of the other wires in your vehicle feed into the vehicle. Simply connect another piece of blue primary wire to the blue wire in the wiring harness and run the primary wire back to the amplifier to terminate in the remote turn on terminal. When you shut the car off the wire loses power and the head unit and amplifier will both turn off. Poke a hole in the rubber next to your firewall to feed the power wire through.