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How To Wire Speakers To A Car Head Unit

Wiring up a new car stereo can be quite a challenge especially connecting the speakers to the head unit. Normally, most car stereos feature a four-speaker system i.e. two front speakers and two rear speakers, each placed in each corner of your car.

Wiring new speakers to the head unit is not necessarily a difficult process, but it can take a few hours to get all components in place.

In this blog post, we’ll detail every aspect of wiring car speakers to a head unit while considering various methods of connecting the car speakers.

Understanding Speaker Wires

If you’re planning to build a four-speaker system (front and rear speakers) then you’ll need to make eight separate connections. This is because each speaker will have separate wiring for the negative and positive terminals.

Typically, all car stereos come with a standard color-coding system that lets you know what each wire color code represents.

Some time back, the color code system used to vary from brand to brand but nowadays, manufacturers use a standardized wire coloring system to make it easier for you to install your favorite aftermarket unit.

As we have already mentioned, a standard car stereo features two wires for each speaker, so those are the colors you’ll need to pay attention to when connecting the speakers. In addition, each speaker will have two color variants for the two speaker terminals. These are;

Right front speaker— Grey wire (+)

Grey with black stripe wire (-)

Left front speaker—White wire (+

White with black stripe wire (-)

Right rear speaker—Purple wire (+)

Purple with black stripe (-)

Left rear speaker –Green wire (+)

Green with black stripe (-)

When installing car speakers to the head unit, you’ll just need to match the above colors to the colored slots on the car wiring harness. This will then be followed by connecting the other end of the wiring harness to the head unit.

If you are connecting for the first time, there is a higher probability of making connection mistakes if you’re not attentive enough. Interchanging the terminals (connecting speakers out of phase) can negatively impact the system performance and lead to irreversible sound quality issues.

There is also a higher chance of causing permanent damage to your components. As such, it is always a good idea to counter-check the polarity of your speakers to ensure that all the speakers are operating ‘in phase’.

Connecting speakers to head unit

The safest and easiest method of wiring speakers to a head unit is using a car stereo wiring harness.

The wiring harness allows you to tap into the factory radio without having to cut the existing wiring. Ideally, the harness is tucked behind the car dash after connecting all the speaker wires.

Your car stereo and the head unit will set the ground for connecting your new speakers. Also, your car stereo and wiring kit instructions are going to dictate whether you need to install a new wire harness to utilize the existing wire harness.

In general, when installing new speakers, you’ll need to run the speaker wires to the existing or your new wiring harness.

Double-check your connections to ensure that the polarity is correctly matched. Once all the wires are in place, you can go ahead and connect the other end of your wiring harness directly into your head unit factory plug.

You may want to wrap the harness using electrical wiring tape or zip ties to hold the wires together and make things tidier. At this point, you can test your speakers while ensuring that they are screwed in place so that they do not move around while driving.

Connecting speakers to head unit without wiring harness

As already mentioned, the easiest way of connecting speakers to a head unit is by using a wiring harness. So what happens when your car stereo does not include a harness?

For one reason or another, some car stereos do not come with a wiring harness, but this should not limit you from connecting your speakers.

The best method of connecting speakers to the head unit without a harness is by soldering your speaker wires to the head unit wiring. Soldering is a pretty straightforward process, and you do not necessarily require prior experience to solder two wires together.


  • i Strip one end of your speaker wire and head unit wire using a stripper or wire cutter.
  • ii Using the soldering iron, apply heat on stripped ends for a few seconds. Next, apply the solder while holding the iron in place to heat the wire up until both ends are fully coated with the solder.
  • iii Hold the coated wires on top of each other. You can then use the soldering iron to melt the solder and coat both wires evenly.
  • iv Place the heat shrink tube around the soldered wires to hold them together. You can use a heating appliance such as a hairdryer or heat gun to seal the two wires together.

This method is more popular since there is less likelihood of making errors, and once everything is connected, the soldered wires don’t break easily. You can also use high-quality electrical tape to wrap your connections.

Alternatively, you can use butt or crimp connectors to hold the wires together if you don’t want to deal with hot temperatures. Crimp clamps use the same principle as soldering, but instead of using solder and heat, the former utilizes crimp connectors and a crimping tool to join two wires together.

While most people argue that crimping is not the best choice, it still provides a solid connection. The most important thing is to ensure that ends are squeezed tightly so that they don’t come apart.


Wiring speakers to a head unit is relatively complex, but as long as you have prior experience with car electrical systems, you should have the system up and running within no time.

The good thing is that you have different connection choices, and most are relatively straightforward. You can connect new speakers using a wiring harness, or crimp/ solder your connection as per installation requirements.

While it is always a good idea to consult a professional before undertaking any project, the above tips will come in handy while trying to connect your speakers more cost-effectively