Learn Your Wiring Words

Automotive wiring
Learn some common car wiring terms before you dive into your electrical repairs. Getty

In the course of working on your car or truck, there will no doubt be terms you come across that are a mystery to you. Understanding the terminology of electrical repair really helps understand and troubleshoot electrical issues in your vehicle. Here are a few of the most commonly used terms when you're dealing with car audio and electronics.


When you see “12V+” you are likely looking at a wiring diagram of some sort.

This is a wiring label, or description of a wire that says it carries 12 volts of positive current. Since modern automotive electrical systems are all 12-volt systems, it simply means there is positive current in the wire, as opposed to Ground. 

Amp (Amplifier)

An amp, also known as an amplifier, is part of a car’s audio system that takes an audio (sound) signal and makes it much louder. The amp also often distributes the music to each speaker through an internal crossover. 


All electrical components are part of a circuit, which is basically a circle of electricity. Using a headlight as an example, the positive current comes from the battery, which goes through a fuse and then to the headlight switch. When you turn on the switch, the positive current goes to the light, makes it light up, then follows the path of Ground back to the battery. All things electrical must have a similar path.


Constant Hot

A wire or circuit that is referred to as a “constant hot” is hot all the time, as long as there’s a battery connected. This circuit is getting power regardless of the position of the ignition key. 


A car battery has two sides, a positive side and a negative side. The negative side is referred to as “Ground” (or “Earth” in the UK).

In most modern vehicles, the Ground side of the battery is connected to the car itself, so any metal part of the car’s chassis can be attached to in order to complete a circuit, making the entire chassis a Ground point when needed. 


In automotive electrical wiring, a harness refers to a number of wires that have been organized into an organized group. Also known as a wiring harness, this group can be as few as three wires, but is often 10 or more bundled together. Wiring harnesses help to organize a car or truck’s electrical system by grouping wires together that supply power to similar components. For example, all of the lights at the front of the vehicle (headlights, running lights, turn signals) may be grouped together. A harness also often has a plug separating it into sections, joining it to a larger harness, or connecting it with an electrical component like an ABD module or fuse block

Head Unit

A car’s head unit is the central control for the car audio system. It may also control navigation or even climate control. It’s that electronic component in the center that does so much stuff. 


The term “hot” can have two meanings in automotive electrical wiring. If you’re looking at a light bulb, it will have two wires connected to it, a positive wire and a negative wire.

The positive wire is often referred to as the “hot wire” or “hot side,” and the negative wire is referred to as the “ground wire.” The other time the term “hot” is used refers to the active or inactive state of a positive wire. For example, if you are testing a positive wire to see if it has power, you’d ask if the wire was hot. If the tested wire turns out to have power, you’d say the wire is hot, or the circuit is hot. 


The negative wire or negative side of an electrical component is connected to Ground, which connects to the Ground side of the car’s battery. In modern vehicles, the term “negative” always means ground.


When somebody refers to “power” in a car’s electrical system, they are talking about battery power, and more specifically, they are usually talking about positive electrical current.

For example, if you say, “I don’t know why the lights aren’t on, there is power coming from the switch,” you’re saying that there is electricity coming through the positive wire to the lights, but they still aren’t on.


In automotive electrical components, like amplifiers or antennas especially, the Remote wire is a kind of switch that tells something when to turn on. For example, there is a remote wire coming out of your stereo’s head unit. When you turn the stereo on, this wire sends a signal to the amplifiers that it’s time to turn on, too. 

Switched Hot

A wire or circuit that is referred to as a “switched hot” is only hot when the ignition switch is in the “On” or “Accessory” position. When you turn the key off, things that are part of a Switched Hot circuit turn off, too. Your stereo is usually connected to a switched positive, or switched hot. 


A speaker is any part of the car that reproduces sound, but usually refers to a speaker in the car’s audio system. Troubleshoot your car's speakers.