In this post, we will talk about your vehicle’s grounding system. Now I know I’ve touched on this subject before, briefly, but I wanted to dive a little deeper to explain why we do it, and why it is essential for the proper functioning of our car audio equipment.

We’ve all heard someone say that good ground is key to having your high-powered amplifiers perform at their peak and without any unwanted issues, but do you really understand how the 12-volt grounding system works? Maybe, but I’m guessing most do not, especially if you are new to car audio or simply not experienced enough yet. 

Let’s change that now, and drop some knowledge on you so you can know how this system works and how to do it properly. 

Be sure to read our Car Audio Wire START-Guide.

The 12-Volt System

Almost every single vehicle on this planet runs a 12-volt electrical system, with a few exceptions, but we are not here to discuss those. We want to know more about the majority of the vehicles on the road, the vehicles we drive on a daily basis, and the vehicles we install our large, or small, sound systems in. So what is the 12-volt system? Well, exactly what its name implies, a 12-volt electrical system that is supplied by a 12-volt battery and charged by a 12-volt alternator. 

The 12-volt battery in your vehicle is basically just a storage device in your electrical system. It supplies the necessary “burst” of power to start your car, but it also supplements the alternator when the alternator cannot keep up with the power demand of accessories such as headlights, car audio components, or when the voltage of the alternator drops below a certain point, like 13.8 volts or so. 

A 12-volt automotive electrical system may sometimes be called a negative-ground electrical system. This means that the vehicle uses a few grounding leads in order to complete the electrical circuit. Typically, there are ground leads from the battery’s negative terminal to the chassis (hence the name negative ground electrical system), and ground from the engine block to the vehicle’s chassis. This ground is typically how your vehicle’s alternator is grounded because there is no “ground wire” coming from the alternator, it is simply grounded through its case to the engine block and then the engine block to the chassis. 

The Grounding System

Because your vehicle’s accessories and electrical system require negative ground in order to function, so do any other accessories you decide to add to that system. This is where things can get a little tricky. Because most car audio equipment, especially amplifiers, require tremendous current, they will also require really great grounds in order to function properly.

Though some accessories utilize a “body shell” ground, which can be sufficient for these accessories, the same cannot be said for any large car audio component such as an amplifier. For car audio, the equipment must be grounded to the vehicle chassis. This point allows for the least resistance and has other benefits such as reduced electrical noise within your system. 

The main reason for utilizing chassis ground for car audio is to ensure there is a path of least resistance for the electrical current, but this grounding method will isolate noise entering and exiting the audio system. For those who may not know, your car audio system, if not grounded properly, can emit electrical interference, or noise, into critical sensors and triggers, causing them to not function as designed or cause damage. In addition, improperly grounded car audio, or any other non-OEM accessories can also affect the vehicle’s main computers and controllers. This can be an expensive fix if this happens. 

Please ensure your chassis grounds are clean, paint-free, and down to bare metal to ensure the ground will be properly effective in completely your car audio’s high-current electrical circuits. 

Connecting Grounds To The Battery Or Using Long Ground Leads

Some so-called, installers will tell you to just connect your amplifier’s ground back to the battery’s negative terminal. This suggestion is almost always a bad idea. Most people don’t understand how grounds truly work. The grounding of most equipment can be shared through device cases, another wiring, or connectors. Having a piece of car audio connected back to the negative battery terminal can lead to very hazardous conditions. In a situation like this, the grounded current, which can potentially be an extremely high-current negative, can be sent through the ground to the equipment which was not designed for such a high current, thus damaging it or worse, causing a fire. 

Another practice that causes issues with grounding car audio equipment is the use of long grounding leads. Installing a ground lead that is far too long will introduce too much in the way of resistance into the circuit which can lead to equipment malfunctioning, wire and fuse overheating, or possibly a fire. The shorter you can make your ground leads from your amplifier, the better the ground will be. I typically try to keep my ground wires around 4 feet or less, if possible. If they need to be any longer, I recommend stepping up to a larger-sized cable to reduce the resistance the longer length can introduce into the circuit.

Ground Loops

A ground loop, or earth loop, happens when multiple points of an electrical circuit are intended to have the same grounding potential but have different potential between them. 

Ground loops are the major cause of electrical noise, humming, and or alternator whining in audio systems. A common reason for a ground loop is connecting multiple grounds together with varying lengths or gauges of cables. The best way to eliminate ground loops is to follow the best practices of the ground the specific car audio component or follow the recommended grounding procedures located within your car audio equipment’s user manual.

Ground Health Check

If you want to make sure your grounds a properly done, or continue to do so, you should periodically check them. If they were not installed in the first place, take the time now to clean them up. Clean the surface of the metal by removing any paint, undercoating, or grime, down to the bare metal. Use a secure method, such as a nut and bolt, to secure your ground lead to your freshly created ground location. You can use some primer, or paint to cover the ground, after installed, to prevent rust.

If you installed the grounds correctly the first time, use this time to inspect your grounds. Make sure the grounding point is still in good shape and there is nothing impeding your grounds, like corrosion. If there is, clean them up, or redo them all together if needed. Maintaining your electrical connections will help your system last, function properly, and play longer.


Though there is a lot going on in this post, dealing with the 12-volt system, especially the grounding side, is pretty easy to understand once you have correct, or more information about the subject. I hope this post has provided you with a little more information about why car audio grounds are important when installing your car audio system. If you like to see content like this, please leave some comments below. 

How to Make a Proper Ground Connection | Car Audio

About The Author Brandon L

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