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HomeTips & GuidesCar Wiring Diagram Color Codes and Symbols – How to Read Them

Car Wiring Diagram Color Codes and Symbols – How to Read Them

About Car Wiring Diagram Color Codes and Symbols, As you may know, for vehicles to function, they have complexly wired electrical systems that can run into problems. 

When this happens, you or your mechanic need a vehicle wiring diagram to trace, diagnose, and rectify electrical system issues. 

However, at a glance, book car wiring diagrams appear complex, which can intimidate you when repairing your car’s electrical systems.

 Fortunately, we will discuss the vehicle wiring diagram and how to read it, plus various car wiring diagram color codes.

What Is a Car Wiring Diagram?

Car wiring diagrams help technicians and mechanics trace a car’s electric systems, sub-systems, and components. 

Instead of names, such as the battery, each component has its symbol on the diagram. 

However, these symbols vary with vehicles, so you must use a legend to determine these symbols. 

In addition to symbols, each car wiring diagram includes lines, charts, and color codes. 

Studying a wiring diagram

Studying a wiring diagram

Common Car Wiring Diagram Symbols

Let’s see some common symbols of these diagrams:

  • Battery – a pair of parallel lines, one long for positive and short for negative
  • Relay – a rectangle with a coil inside
  • Switches – a break in a straight line
  • Ground connection -an arrow of horizontal lines facing downwards

Automotive Wire Color Codes

After the symbols, now we go to wire colors which means a lot in the wiring diagram. The most common color codes are:

  • Black – for the negative terminal
  • Red – for the positively charged circuit
  • Yellow – means constant power
  • Blue – Power antenna
  • Plan green or green with white stripes – grounding

Occasionally, these colors come with numbers or letters, such as B for black and R for red. As we said, each car may have different coding or letters, so check the manual.

A wire with different colors

A wire with different colors

How to Read Automotive Wiring Diagram

In the old days, the wiring diagram was easy to read since it involved just a few circuits in a car system. 

However, as cars advance with several electronics,  the car wiring diagram gets complicated. Lucky, it’s  still not difficult to read using the steps below:

Begin with a Specific System

It’s common knowledge that you do not need the entire wiring diagram but just a portion. 

For this reason, begin studying one circuit from end to finish to avoid confusion. For example, if you are repairing the ignition, concentrate on that system. 

Trace the Power Flow

After identifying the fault power to repair, follow its path carefully. Start at the battery symbol and go to the grounding that completes the circuit. 

While doing so, identify associated fuses and relays since their damage can result in a disconnection. 

Connectors and Junctions Identification

The next step is identifying power supply splits, such as connectors and junctions. Typically, these are areas in the circuit diagram where the wire splits from the main circuit. 

Mostly, they split to power other components in the system. This step is necessary to ensure the split circuit components get enough power. 

Compare the Drawing with the Physical Wiring

After identifying and following the faulty circuit on the diagram, logic dictates comparing it with the actual wiring. 

Doing so lets you visualize each component of your car as it appears on the drawing.

 In some cases, you may find components in the diagram don’t coincide with what’s under the hood. 

In such instances, it means the former owner of the car or the mechanic did some modification to the system.

 For this reason, it’s vital to compare physical and diagram components before making any decision.

Make Notes

Generally, wiring diagrams get complicated, and finishing the repair in one instance may not be easy. 

Therefore, I recommend making notes directly on the diagram since it’s yours. Label all the parts for future reference or easy remembrance when you return to the repair. 

Doing this helps you know what the mechanic changed or swapped, which can help you understand it better.

Testing a car engine

Testing a car engine

Wrap up

With the above simple yet detailed steps, you can read your car wiring diagram easily. As a first-timer, start with the simplest diagram to get the hang of things. 

Eventually, go to the complex circuit, but if you have a problem, consult a professional.

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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