how to hook up subs to factory radio

How to Hook Up Subs to Factory Radio – Complete Guide with Steps, FAQs & More

If you’d like to hook up a subwoofer or powered subwoofer to a factory radio or stereo, there are certain safety concerns and procedures to be aware of. 

When I installed my first subwoofer years ago, it took me much longer than it should have since I didn’t look up many key details. 

This post provides step-by-step instructions on how to hook a subwoofer to a factory radio or factory stereo. 

Quick Summary

In this post, we will discuss:

  • Items you’ll need to hook up a subwoofer to a factory stereo
  • How to install a subwoofer on a factory stereo
  • How to hook up a powered subwoofer to a factory stereo
  • Some frequently asked questions (FAQs) 

So without further ado, let’s get into it.

Items Needed to Hook Up a Subwoofer to a Factory Stereo 

Like most of our tutorials, we recommend that you gather all of the required tools first. This will save you a lot of time during the installation process since you’ll have everything you need on hand. 

power wire ground wire speaker wire power cable blue wire factory amp grabbed speaker wire signal

The items you’ll need include: 

  • Pliers 
  • A flathead screwdriver
  • A socket wrench
  • Tape
  • A knife
  • Subwoofer box
  • An amplifier
  • RCA cables 
  • Additional relevant speaker wires
  • A line output converter
  • An inline fuse with a rating of at least 50 amps
  • A wire harnessing kit

Once you have everything gathered, you can start installing the subwoofer onto your factory radio or stereo. 

Important note: Depending on the model of your factory radio, your subwoofer, and your car, you might need additional materials and/or items. 
It’s a good idea to check out the instruction manual for your subwoofer, radio, and car to ensure you have all the tools necessary before you start.

How to Install a Subwoofer on a Factory Stereo (Step-by-Step Instructions)

To properly install a subwoofer to a factory radio or stereo, follow these steps: 

Step 1: Determine a Spot and Properly Place Your Subwoofer 

The very first step is to assess your car and determine where you will situate your subwoofer box and the subwoofer inside of it. 

It’s very important that you take your time with this step and really assess what the best spot would be. You don’t want your subwoofer to be too cramped since this can lead to overheating issues. 

Ensure it’s in a space where it can get proper ventilation. 

It’s also a good idea for the space to be somewhere where you can easily reach it. That’ll make it much easier to make adjustments on the fly and it’ll be much easier to clean as well. 

power cable remote turn on wire negative battery terminal sound system all the wires car stereo

Lastly, you must ensure that all of the wires that need to be connected to it will be able to connect freely. It’s important that none of the inputs of your subwoofer are blocked by any part of your car such as the seats, etc. 

Step 2: Disconnect the Battery 

Before we actually start the wiring process, it’s very important that you disconnect the battery from your car. If you do not perform this step, then the installation process can not only be tricky but also, fairly dangerous. 

It could lead to electrical shocks and hazards, at worst. Even if you don’t get shocked, you’ll still be risking damage to your car stereo, amplifier, and subwoofer. Hence, it’s just an overall better idea to disconnect the car battery. 

To do so, you don’t need to remove the battery entirely from your car. All you have to do is remove the negative terminal connection. The negative terminal is marked by a “” symbol on your car battery.

Remove the nut and gently pull out the wire. Set this wire gently and securely on the side hood of your car. 

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Step 3: Connect All the Relevant Speaker Wires

At this point, it’s a good idea to have the instruction manuals for your factory stereo as well as your subwoofer on hand. They can provide you with critical information on how to connect the speaker wires properly. 

The different types of wires you’ll have to connect include: 

Power Wire

You’ll need to connect the power wire to the positive terminal of your battery. Once that connection has been made, you can run the power wire underneath the carpet of your vehicle. 

Please note that you may need to attach the wire to a fuse holder to ensure it’s long enough to reach the car battery.

Quick tip: It’s a good idea to have your fuse as close to the car battery as possible as this can reduce the chances of short circuits. 

Ground Wire

Next, you must connect the ground wire to any metal surface of your vehicles such as the base frame or the chassis. This completes the ground loop and ensures that the sound quality is noise-free and clear. 

negative battery terminal sound system all the wires rear deck speakers factory system
Quick tip: If you hear static noise during music playback on your factory stereo, then it might be because one (or more) of your components are not grounded properly. 

If your car has paint on its base frame or chassis, then you’ll need to remove it with a paint scraper or sandpaper. It’s super important that the ground wire comes into contact directly with a metal surface and not one that’s painted over. 

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Speaker Wires

The speaker wires are what are connected to the back of the factory head unit.

You can run these speaker wires through a line output converter to make sure they can easily fit with your subwoofer and amplifier. 

A note about line output converters: If you have a stock stereo, then you’ll need a line output converter to connect it to a subwoofer. 
This is because factory stereos do not have a preamp output that can convert their signals into RCA signals. 
This is where line output converters come in. They help you convert the signals so that they can be utilized by your subwoofer.

Connect the speaker wires to the appropriate terminals on the line output converter. 

RCA Cables

Connect the RCA cables to the appropriate terminals on the line output converter. Connect their other sides to your subwoofer. 

Please note that the RCA cables should be placed as far away from the power wire as possible. This will ensure that no interference occurs and the best possible sound quality is achieved. 

Step 4: Reinstall Everything 

After you have connected all of the wires securely, it’s time to put everything back together. 

Start off with your factory stereo. Make sure that all speaker wires are secured inside the dashboard panel and then, gently push the stereo in so that it locks firmly into place. 

If the factory stereo requires screws or bolts to be fitted in, go ahead and screw them in. 

Next, check that your subwoofer is properly held in place. Lastly, make one final check to ensure the power cable, speaker wires, and RCA inputs are all properly connected. 

Once you’re sure everything’s in place, you can reconnect the car battery by re-establishing the connection at the negative terminal. 

Step 5: Test Your Car Subwoofer

The last thing to do is test the sound quality of your subwoofer. 

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powered subwoofer bass system car audio vehicle’s negative battery terminal wiring harness

When you want to check the sound quality, it’s a good idea to play a variety of different music that comprises a wide range of frequencies. 

You want to check the high, mid, and low frequencies to ensure that the speaker wire signal is properly being sent to the subwoofer. This will also test the quality of your subwoofer to see how well it handles all of these different frequencies. 

Frequently Asked Questions (FAQs) 

Do I need to buy an aftermarket stereo to connect a subwoofer to my car?

While it usually results in better sound quality, it’s definitely not a necessity. As we clearly explained above, it’s definitely possible to connect a subwoofer to a factory radio or stereo. 

It can still sound fairly decent as long as you take your time to make the connections properly.  

Is it necessary to have an amplifier to connect a subwoofer to a factory stereo? 

It’s not absolutely necessary to have an amplifier to connect a subwoofer to a factory radio or stereo. You can definitely get away with not having an amplifier if you’re trying to save some money. 

However, it should be noted that the process for installation without an amplifier is relatively more complicated.

What is the purpose of a remote wire on a stock stereo?

You can utilize the remote wire of your stock stereo to either connect to the antenna of your radio or to the fuse holder of your vehicle. 

When you install a subwoofer, the remote speaker wire gets connected to the fuse holder. 

Is it worth it to add a subwoofer to my car? 

It depends on what you need from your car stereo. If you’re someone that enjoys music and wants to have the best audio-listening experience possible while driving, then it’s absolutely worth it. 

Just make sure you do the right amount of research to ensure you get the most suitable subwoofer for your car. 

Can my factory head unit power my subwoofer? 

Yes, a factory head unit can definitely power your subwoofer. However, this can strain your car’s battery in some cases. 

In most cases, it’s a better idea to have an amplifier that can take some of the load off of the head unit. 

Wrapping Things Up… 

As you can see, the process to hook up a subwoofer to a factory radio is fairly simple as long as you keep safety concerns in mind. 

Take your time with the installation and ensure that everything is properly grounded. You’ll have your subwoofer set up in no time. 

If you have any further questions regarding the installation process, please reach out to us in the comments section below. 

Our experts have reviewed the latest radio so you can buy it without worrying about the quality at all. Do check them out before you decide to buy something. 

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