How to Install a CD Player With a Factory Amp

Factory amp interface
1. Locate the amplifier signal wires. In European vehicles, these wires are often labeled on the factory radio itself. For most domestic vehicles, these wires are the same wires that feed the speakers on models that are not equipped with a factory amplifier. In addition to signal wires, you must locate the amp turn-on wire. This is the wire that tells the amp to turn on when the stereo is on.
2. Cut the ends off a set of RCA cables. Plug the RCA cables into the RCA pre-outs on the back of the stereo to be installed. Strip back about 1 inch of insulation from each cable and separate the center conductor from the ground shield.
3. Connect the RCA plugged into the front left RCA output to the front left signal wires to the amplifier. Connect the center conductor to the positive wire, and the shield conductor to the negative wire. Repeat this for the front right, rear left, and rear right signal wires.
4. Solder all connections, and seal with electrical tape or heat shrink tubing. Connect the remote turn-on wire from the CD player to the turn-on wire for the amplifier. Usually, the CD player's remote turn-on wire is blue with a white stripe.
5. Turn on the CD player and listen. If connected properly, you will hear music playing through all four speakers and subwoofer (if equipped). Start the car and turn the volume all the way down to check for noise. With the volume set to zero, no sound should be heard. If a high-pitched whine is heard, and the frequency increases when you press the gas, check for a proper ground connection on the CD player and the signal wires.