A 20 ft (6. 1 m) power wire. A ground wire at least 3 ft (0. 91 m) long. A 15 ft (4. 6 m) RCA wire with both red and white connectors. A 15 ft (4. 6 m) blue remote wire. Speaker wire, which can also be bought separately. A 60-amp in-line fuse and fuse holder. Crimp ring terminals for connecting the wires. A plastic crimp connector for the remote wire.

Note that, for the best sound quality, the amplifier should be as close to the subwoofers as possible. Some subwoofer systems include a built-in amp, making this less of a problem.

Disconnecting the battery deactivates all electrical systems, making the wires safe to touch. You can leave the battery in the vehicle, but make sure the red cable doesn’t come into contact with bare metal. Inspect the battery before touching it. If you notice corrosion, put on rubber gloves and safety goggles.

Many cars have an opening near the glovebox on the passenger side. You can also get into the car and look for the opening there. If you don’t see an opening, you may be able to make a hole with a sharp knife or drill fitted with a steel bit. Be careful to avoid cutting any wires.

Routing the wire through the firewall hole can be a little tricky. To make this easier, straighten out a hanger, then curl one end into a hook. Use the hook to guide the wire. Most cars have a little bit of extra space along the sides for wire storage. Expose these channels by lifting up the carpeting or trim panels. The trim panels are often held in place by plastic pins. Use a flathead screwdriver to pry the pins off. Note where each panel belongs before removal so you have no trouble reinstalling them later.

The in-line fuse you will use to power the subwoofer should be no more than 6 in (15 cm) from the battery. Cut the wire so it extends from the battery to where you plan to place the fuse. [6] X Research source Some wiring kits come with the fuse assembly already put together. If this is the case, then you do not need to connect any wires to the fuse assembly. Just run the wire so that the end with the fuse is closest to your battery.

Wire strippers are the best tool to use if you want to remove the insulation without risking the underlying wires. You can also use something like a sharp knife or sharp scissors, but be very careful to not damage the exposed wire underneath.

The power wire should be secure in the fuse holder. If it feels easy to move, tighten the terminal with the Allen key a little more. Be careful not to overtighten it.

Position the fuse holder in a safe spot where it won’t be jostled around while you’re driving. Try anchoring it to the car frame with a screw or cable tie.

The ring terminal needs to fit on the positive terminal of the battery, which is usually labeled and is recognizable by the red cable connected to it.

The remote and RCA wires should always be far from the power wire, if possible. Otherwise, they may interfere with one another and have a negative effect on the sound quality.

Some stereos have screws that require a Phillips screwdriver to remove. The stereo removal process varies between models, so refer to the owner’s manual for your car to get more specific details about how to access the stereo’s wiring.

Note that the stereo may have several red and white outlets. Look for the ones labeled R/SW. They manage audio in the rear (R) part of your vehicle.

The blue wire on the stereo may be labeled remote, antenna, or amplifier. Another option for joining the wires is to solder them together. It involves stripping and heating them with a soldering iron. Place a shrink wrap tube afterward to protect the joint.

If your vehicle doesn’t have a contact point, you can install one. Use a masonry bit to drill through the metal, then insert a screw or bolt. Make sure you don’t drill through anything other than the metal!

You don’t have to eliminate all of the paint, only the material around the bolt. When you install the ground wire, you will be able to see where it rests on the panel. Remove any paint underneath the ring connector.

Make sure the wire strands are firmly wrapped together so they fit well inside a connector. If the wire doesn’t do its job, it could blow out your system or shock you.

Your wire kit most likely came with a couple of ring terminals, but you can always buy more from a hardware store. Consider placing a lock or star washer on top of the ring terminal to keep it pinned. One of the most common problems with subwoofers and amps is when the terminal doesn’t have full contact with the bolt or screw.

The amp wires connect directly to external subwoofers. Plan on connecting each subwoofer with separate speaker wires.

The power slot may also be labeled as “Battery” or “12v. " The slot is often controlled by a small screw. Turn it counterclockwise with a Phillips screw to open it. Close it back up after inserting the wire. If you’re using a combination amp and subwoofer, look for wiring slots on the back of the subwoofer.

The remote slot may be in the middle of the other slots. When possible, arc the wires in a gentle curve to protect them from damage. Don’t try twisting them at a harsh angle to reach the slots.

The ports on an amplifier are typically color-coded. If they are, use the colors to double-check that all the wires are in the correct slots.

Speaker wire is often recognizable by the bronze-colored insulation that makes it look similar to a bare wire. It can be plugged into either the positive or negative ports as long as you match them on both devices. Some types of speaker wire consist of separate, color-coded wires. Plug the black wire into the negative ports and the red wire into the positive ones.

Make sure the RCA plugs are in the correct ports. If your system doesn’t produce the sound quality you expect, you may have switched the RCA cables by accident.

If you notice problems, it is likely from a faulty connection. Make sure the wires are secure and well-connected, including the ground wire.