How to Install a Head Unit A.k.a. Stereo in a Car

It really is fairly simple to install a head unit in a car. Try not get overwhelmed or make it more difficult than it truly needs to be. Disconnect the car's positive battery terminal under the hood so any bare wires don't short out. Then locate all wires needed, connect them, secure the head unit, reconnect pos. terminal and that's it.

Difficulty: Moderate

Instructions

Things You'll Need:

• wire cutters, wire strippers/crimpers, butt connectors a.k.a. crimps, small flat head screwdriver, car owner manual, head-unit installation manual, and a little patience.

1. The first group of wires on the back of the unit include a black ground, a red constant power, a yellow alternating power sometimes, a blue remote-on wire which switches the unit on and off when the key is turned. The second group of wires on the back of the unit are simply speaker wires with the negative marked with white stripe. Every car is wired at the factory to include a stereo so it's just a matter of locating the wires you'll need and connecting them with the wires on the back of the unit.

2. Start by unhooking the car's positive battery terminal under the hood. A 12V tester comes in handy here. Find the black ground and then connect with crimper and butt connecters. (use red or blue size connecters for best connection) Next the blue remote-on wire will connect to a blue or sometimes brown wire that will light your test light only when the key is turned to ACC or start position. Connect those wires. Then find a red power wire that lights your test light even when the key is off and connect it to the red power wire of the unit. More than likely the wires of the unit are connected to a harness which the unit slips into at the end of the installation.

3. Now with this done it's time to hook up the speakers. Use the car's stereo wiring diagram in the manual to see which wires are for what speakers. Then match those up with the wiring diagram in the installation manual for the head unit. For a two-speaker system you'll hook up a total of 4 wires. For a four-speaker system you'll hook up a total of 8 wires. That's (2) wires per speaker!

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Tips & Warnings

• If you don't have a manual for the car's wiring diagram you can also remove the speakers one at a time and check to see what color wires are connected to the + and - terminals and then you know what wires go to which speakers in the dash.
• Don't forget to unhook the positive terminal of the car's battery under the hood! Failure to do so can shock you, blow fuses, and make this project more difficult in the long run.