Over the past 10 years there have been so many new developments on car stereo systems and with this, new techniques to installing head units. There are some opinions of what is right and wrong when wiring up a system, the fact a technique works, does not necessarily means that it’s correct.

The Majestic Modifications Opinion

Being an expert opinion, they recommend first, if applicable, always use the harnesses. The aftermarket wiring harness will usually take the guesswork out of the installation. These harnesses attach to the vehicle’s factory wiring harness and give you a color coded installation. You just attach red to red, yellow to yellow, etc. But is that all an installer should know? What if you don’t have the wiring harness? Just follow the below guidelines.

Using a multimeter, find the power sources in the harness. One source will be continuous 12 volts, the other will be the ACC (ignition) 12 volts. These two will go with the yellow and red wires from the aftermarket head unit’s harness. They are labeled accordingly. It is usually a good idea to attach the ground wire to the frame of the dash. Most of head units come with a connector for this already attached to the ground wire. Be sure you have a good ground wire connection.

Secure these in place with some solder and shrink tubing. Slip the shrink tubing over one of the wires to be connected and move it out of the way. Connect the wires and dab a little solder on the wires. Let cool and then slide the heat shrink tubing over the connection. Heat with a heat gun/hair dryer to shrink the tubing to fit.

About The Wiring Colors…

As there exist “typical” wire colors, chances are you will find different ones. You can try two techniques to find the right wires. Clip the rest of the wires from the factory harness. You can test the speakers with a good 9 volt battery to see which speakers are which. Two wires connected to the same speaker will make it pop. Note which speaker makes the pop and attach it to that speakers wiring from the head unit. You can turn the unit on and make sure the wires are the right polarity. A reverse wired speaker will not have as good a sound as a properly wired one. Continue the technique until all the speakers are connected.

Another way you can trace the speakers down is to turn on the head unit, but be VERY careful not to cross any wires. Start with a pair of wires, and attach them one at a time until you get sound. Note which speaker it is and attach it to that speaker’s wires from the wiring harness, taking note of polarity. Continue until all the wires are in place. Zip tie the wire together and neatly tuck them behind the head unit.

Be sure that RCAs or signal wires are running away from any power wires or sources, and are not run parallel to them.

A Neat Trick

You can attach the 12 volt acc to the illumination wire, and you will be able to turn the unit on with your parking light switch. Take note, that anytime the unit is on, the dash panel lights will be on too, but you won’t notice them in the daytime. The illumination wire is used to turn the factory radio lights on at night.

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Installing Speakers

Speakers are a very important part of any quality audio system. While you may be able to get sound from your factory speakers with that new head unit, replacing those factory speakers with high quality aftermarket ones can make a huge difference in the quality of your sound.

For your first speaker installations, you should try to replace the speakers in the factory mounting holes. This is a fairly simple procedure, but can require removing interior panels to access the speaker mounting locations. This method is advantageous because you can use the existing brackets and wiring.

More complicated is mounting speakers in locations that didn’t originally have speakers, or putting larger speakers in existing mounting locations. This will often require metalworking and building boxes and baffles to accommodate the new speakers. But if you don’t have any factory speakers, or they are in bad locations, this may be your only option.

Just be careful, and if the project requires a lot of reshaping of the cars metal locations, you should consider having it professionally done; this kind of work is best done with specific tools that most home enthusiasts don’t have. such as plasma cutters and pneumatic sheet metal formers.

If you have ever looked into buying a new car stereo system, you probably realize that the costs of having it professionally installed can almost double the cost of your new system. But there is always the other option: do it yourself.

While a car stereo installation can be complicated, there is nothing in particular that prevents you from doing it yourself, as long as you are willing to put in the time and effort to learn how before you diving into the project. Not only can you learn a lot, but there is always a sense of satisfaction when you fire it up for the first time, knowing you did it all yourself.

Patience and caution are paramount here. Some car stereo equipment is quite expensive, not to mention the price of your car to begin with! So be careful, proceed slowly, and if you have doubts, find out the answer to whatever is bothering you before you continue. Not taking it slow and carefully can lead to a botched install or even broken equipment or a damaged vehicle.

Beginners are advised to keep it simple the first time around. Don’t try to install a full car theater system with LCD displays and DVD players or video games for your first installation. Start with the head unit. This is both the easiest and the most critical thing to get right the first time.

Often the wiring harness that plugs into your factory stereo will need an adapter to get the correct electrical connections to the power and speaker system already in your car. Being able to reuse your factory wiring makes things much easier down the road when replacing the factory speakers. Don’t just cut the harness off! Use an adapter. If you ever want to replace the head unit again, things will be much easier if you can simply unplug the old adapter and replace it with a new one for the new head unit.

The head unit will also probably require an adapter kit of some kind to fit properly in the factory dash hole. Most factory systems are either custom or what is called “Double DIN”, whereas most aftermarket head units are single DIN form factor. Sometimes, filing away parts of the trim surrounding the mounting area will be needed. Do some test fits before you bolt everything down.

Stay tuned for the second part of these car stereo installation posts…