Is Red or Black Positive in a Car?

Is Red or Black Positive in a Car?

Working on cars can be a challenge when you don’t have the experience, especially when it comes to electrical wiring. Working on cars without proper knowledge of the electrical wiring can not only be frustrating, it can also be dangerous. One of the most basic lessons for car repair is to be able to identify the positive and negative wires. This article will show you how to tell decipher the colors of electrical wiring diagram or schematic and how to tell which wires are positive and which are negative so that you can make repairs safely with the proper knowledge.

Electrical Wiring in Cars

Automobiles have extensive wiring systems where many sires are bound together with a plastic sleeving or insulating electrical tape. The electrical wiring is typically made of copper or aluminum and is color-coded in a system referred to as a loom. The loom is often divided into parts which are joined together with sockets and plugs. This way, the wiring bundles can be refitted by section rather than by an entire bundle.

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Modern cars may have electrical wiring which are embedded in compact, plastic strips. These types of wiring are most commonly found in the relay controls and in accessories. The connectors on the wires are typically crimp connectors of different colors. The bare end of a wire extends of either end of the connector sleeve and then pinched using crimping pliers. The connector sleeve color is dependent on the size of the wires. There are several connector sleeves located where the wires branch off.

Wires connect to other components in the vehicle using terminals that are covered with plastic. The terminal pushes onto a spade terminal. The electrical wiring is mounted to the body of the car to keep them from coming in contact with other components. The wiring has sharp edges lined with a rubber grommet and runs through openings

Electrical Wire Colors & Symbols

The industry has not established a universal code for wiring colors; however, most manufacturers use the same design. However, not all manufacturers use the unspoken standard; therefore, the wiring colors can depend on the make and model of the car. The majority of automobile wiring diagrams use the Color-Code Legend which uses two diagrams and circuits to present the rules for all circuits according to Ohm’s Law. Each circuit has to have a load, and each load must have a ground side and a power side. The Color-Code Legend began as a simple illustration of a very basic electrical wiring system and quickly evolved into a more complex diagram.

Every car comes with the Color-Code Legend, a graphical representation of the circuitry for that car. The abbreviated codes may represent circuit paths, a part, or information about a specific component. The Color-Code legend displays which color means what. The electrical wiring diagram uses different symbols to represent the ground, resistor, switch, and battery in the wiring system. There are generally the same four symbols on the electrical wiring diagram: an image of plates or layers which resemble the internal structure of the battery is the symbol for the battery, an image of a connector going in a downward direction is used for the ground, a closed or opened circuit path for the switch, and an image of energy flow being impeded is used to depict the resistor. Beyond these four symbols, there may be other secondary symbols, such as for the case ground or the variable battery source. More advanced electrical diagrams may also show the circuit paths and amps for the system. The case ground symbol is depicted by an image of an arrow crossing over. These types of secondary electrical wiring symbols are actually universal, which makes it easier to interpret them.

The electrical wiring diagram also uses two-letter codes to identify the type of wire. The first letter of the code represents the color of the wire. The second letter represents the wire striping. If the code reads BR, that means the wire is blue with a red stripe.

The identification of the voltage conditions in the circuits is where the color identification process really begins. Each circuit has a specific voltage condition and differences can be viewed by color. The simplest of the circuit colors is green. The ground is represented by a ground symbol that is green. Red is a symbol of power throughout the diagram. The circuits which are directly associated with power are red. The red and orange wires are live.

ORN Symbol

Advanced electrical wiring diagrams use one symbol, the ORN symbol, for the color and size of the wire. The ORN symbol is usually depicted on the diagram as a color spelled out or abbreviated with four letters or less.

Wiring Colors

The color of the wire in a vehicle is very important. Factory service manuals also provide electrical wiring diagrams with wire color information, symbols and definitions. The schematics also show how the wires are connected. Two types of connection are made with the electrical wiring in your car: soldered connections and unsoldered. Large, or oversized wires are soldered, as well as wires which are spliced together. Any other type of connection is solderless. These wires have insulators that are color coded to guide in which gauge wires to use. The colors for wires may also be different depending on the region. The United States has the following wire color codes:

Phase 1: Black wire

Phase 2: Red wire

Phase 3: Blue wire

Neutral: White wire

Ground: Could be green, bare, or green with a yellow stripe

Universally, a wire of most colors is positive and a black or blue wire is negative. However, in Europe, manufacturers were prohibited from making red is positive, black negative wire coloring until The BS 7671 wiring regulation in 2006. Most of the wires were orange until the UK adopted the more standardized coloring for the wires. Changes in the electrical wiring codes results in fixed electrical cables with the same wire colors. The UK electrical wiring colors are depicted by one letter, such as Y for yellow, and are coded are as follows:

Prior to 2006 After 2006

Neutral: Black wire Neutral: Blue

Single phase: Red wire Single phase: Brown

Protective earth (PE): Green Protective earth (PE): Green with

with a yellow stripe a yellow stripe

The blue wire is now also considered neutral and transfers electricity away from the component. A brown wire transfers electricity to the component. The green and yellow wires are also referred to as earth wires and prevent undesirable paths of electricity by earthing the component.

Canada also has its own electrical wiring color coding. The wire colors for Canadian vehicles is as follows:

Neutral: White

Single Phase: Red or Black

Protective earth (PE): Green or green with a yellow stripe

AS you can see, different regions have their own preferences for labeling the wires and circuits in the electrical wiring diagram. However, there is usually some degree of similarity in the labeling.

Installing, Jumping, and Disconnecting a Battery

Many automotive services and repairs require things like battery testing, using jumper cables on a dead battery, the reconnection of terminals after installing a battery or the disconnection of the battery terminals in order to work on the car without electricity. However, many people are squeamish about working with live electrical wires. To remove a battery, or to simply disconnect it, you must know which color is which.

It is of paramount importance that the battery terminals and the jumper cables are matched up with the correct colors. When it’s time to disconnect your battery, look at the colors of the wires connected to the battery terminal. There should be a red wire connected to the positive terminal and a black wire bundle going to the negative. When using jumper cables, you must match the cable color to the terminal color. The red jumper cable must be attached to the red terminal and so on. If you’re still not sure about the battery terminal colors, there should also be positive + and negative – symbols on the battery. Look for these symbols and use them to properly connect the jumper cable to the battery.

You Don’t maintain Your car battery

One of the most common reasons why your battery is bad is that you didn’t maintain the battery. Failure to look after your battery along with other components in the vehicle will cause the battery to decay quicker. A bad battery can also cause other components to become damaged and this can cost a lot to fix at the dealership – you shouldn’t be wasting money at the dealership.

If you want to avoid battery problems and save $100s of dollars that you’ll spend at the auto repair shop, you’ll need to service your vehicle often – you can use our mechanic-rated Auto Maintenance and Repair Manual to do this. It’s basically what mechanics use to go through your vehicle to check if there are any problems that need fixing. As soon as they notice the most minor problem, they’ll ask you to fork out some money even though it’s a problem you can fix yourself in minutes – the manual will teach you how to maintain your vehicle every few thousand miles and it’ll teach you how to fix minor problems that mechanics will ask you to pay for; saving you money in the long run.

A lot of our readers have the Auto Maintenance and Repair Manual printed on their garage wall and 92% of them haven’t visited the auto repair shop in the last year because they know what to do to avoid problems. All it takes is giving your vehicle a little attention every few thousand miles and you’ll never spend money at the workshop again.

Who Cares about Wiring Colors?

Aside from the automotive mechanic, who really cares about the electrical wiring colors in an automobile? Well, over the years, electricity has increased significantly in presence and function in modern cars. Many mechanical features have been replaced by sensors. Many of the components in modern cars come with an electrical design, such as push button start features, the fuel pump, and the brake switch. In fact, the newest cars are totally electric, eliminating the internal combustion engine. Overall, all of the warning lights on your dash require an electrical signal from a sensor. Therefore, it certainly would not hurt to learn a bit about the electrical wiring and what the colors mean.

When jumping a dead battery, if the jumper cables are connected to the wrong battery terminal, a spike in electrical power will damage the battery and possibly parts of the electrical wiring system. The insulation inside the jumper cables will likely melt until you can actually see bare wiring with lots of sparks. The fuse will also be abused and may blow from the load.

The electricity that runs through to the sensors and the engine control unit (ECU) can be blocked or be shorted when any of the wires are damaged. Some components will not receive sufficient voltage or may not receive any electricity at all. When this occurs in the vital components, such as the ignition switch, it can prevent your car from working at all.

Faulty circuitry can also be the problem as the brake light switch must have enough voltage to work, There could be a problem in the wiring or a fuse could be blown. If the problem is electric, the wires and fuses can be tested to determine what component no longer works.

Many times, when things go bad in the electrical system and you don’t know which wire(s) is the problem, any blown fuses should be replaced first. If the electrical problem persists and the fuses were not a part of the problem, the next step before replacing any wires is to replace the wiring harness. To do this, remove the old connector by cutting it off. Strip the wiring and twist it. Connect a new switch using a splice connector. These quick fixes are simple to do and can prevent very expensive, and sometimes unnecessary repairs.

Safety First

Great job! You have become an expert on automotive electrical wiring schemes and you know how to deal with your battery. Remember, electricity is no play thing; therefore, you must always practice safety whenever you are dealing with electrical components.

Job Guthiri is a freelance writer with 3 years of experience writing for Motorsrun and other established automobile outlets. His focus and key interests are Tacomas and maintenance. Read our Editorial Guidlines and Fact Checking process.