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HomeTips & GuidesDIY Wire Harness Kit – How to Build and Install

DIY Wire Harness Kit – How to Build and Install

About DIY Wire Harness Kit: Since a wiring harness carries data and power to your car components, it’s vital for its functionality. That is why you see many electrical components coming with their wire harness from the factory for efficiency and reliability. But sometimes, you may need to make your harness to improve the stock or fit your usage. For this reason, I will show you how to create your DIY wire harness kit.

What Components Are Included In the DIY Wire Harness Kit?

When making your custom wiring harness, you need to have the following components:

Wires and cables

As you may expect the main part of the harness is the wires that carry the information and electrical currents. You can use either stranded or single conductor wires of aluminum or copper depending on your project.

While here, ensure your wires are of the correct gauge (same or different) based on the power they will carry. You may also want to use standard color codes for uniformity and easy identification.

For example, black/red for positive, white for negative, and green for grounding.


You will also need to determine the connectors you will use for your harness to connect to the electrical component.

Depending on the type that appears on the devices you want to connect, you may use either male or female connectors.

Some connectors include eyelet connectors, socket-type connectors, and other electrical connectors.

Wire connectors 

Wire connectors 


Remember, your wires need proper termination to prevent fraying and connect with the connector or the device. For this reason, you will need safe and perfect wire termination, which can be insulated or non-insulated hooks and rings.

Protective materials

Depending on the usage, you may need to protect your wires from the environment, current spike, and contact with others. For this, you will need insulators such as conduits, sheaths, and sometimes fusible links.

What Aspects Do You Need to Consider When Making a DIY Wiring Harness Kit?

For your harness to work safely and efficiently, you need to know its other purpose apart from data and power transport. While here, consider what other specifications you need to add apart from connectors and cables.

For instance, if it works in vibration-prone areas with electromagnetic interferences, account for that. With that said, let’s see some things you should keep in mind:


As mentioned above, the wire gauge or its thickness determines how much current it can carry without burning. You may know that thick wires carry more current, but also consider the length.

The longer the wire, the bigger the resistance that loses voltage. Your wire must also withstand the environmental conditions of its usage.

For instance, it must have a good rating for hot areas application plus quality coating and insulation to prevent moisture.

Lastly, check if you need an abrasion-resistant wire if you intend to use it in such environments. While here, ensure it can withstand mechanical stress such as bending and twisting without breaking or losing current.


You must also know the connector type to ensure your harness connects with your intended device. Remember your connectors should be standard to ensure a seamless connection with your existing devices.

Apart from ensuring a safe and efficient connection, the connectors must protect your wiring from EMI and vibrations.

Therefore, choose connectors with proper insulation, high-quality connection pins, and correct wire gauge.

Use Your wire size and gauge, the circuit type, and current quality as a guide for choosing connectors.

Different electrical connectors

Different electrical connectors

Wiring Diagram

Before you can even create the wiring harness that you need, you must have a wiring diagram. The diagram is typically a detailed drawing showing the wires, connectors, location, and other details.

It may also include routing and the surrounding environment to help you know what type of wires to use. I recommend using professional tools to make a proper wiring diagram instead of just hand drawing.

It should meet safety standards and help you save money. In addition, it must account for bending, twisting, routing, and placement of cable ties for neatness and safety.

Protective covering

Your harness protective covering protects it from environmental factors, ensuring efficiency, safety, and longevity. Before knowing what covering to use, you must figure out where you want to use your wire.

As mentioned above, consider heat, chemicals, moisture, EMI, vibrations, and other conditions.

Your wire protective covering/sheathing must withstand all these conditions. In addition, you can use electrical tape/ heat-shiring tubing for further protection and cable ties for neat bundling.

Tools and Parts Needed for DIY Wiring Harness Kit

For a successful project, consider the following tools you may need.

  • Electrical tape and cable tie: As we said earlier, you will need cable ties to neatly bundle your wires for safety. You can also use electrical tape to seal any exposed joints and conductors for added safety.
  • Soldering gun. You use a soldering gun to melt a solder that connects wires to terminals or connectors.
  • Wire cutter, stripper, and crimper: You usually use a wire cutter to cut the length of the wire you need. You may then need a wire stripper to remove the insulation at the end of your wire, revealing the conductors. Finally, a crimping tool is necessary for crimping your connectors to your wires.
  • Working bench: You may also need a working bench with ample space for your items and a clamp for holding your wires.
  • Dielectric grease: You use this to prevent corrosion and as a lubricant when joining your wires harness to its component.
Some tools for building a harness

Some tools for building a harness

How to Create a DIY Wiring Harness Kit

  • First, study your wiring diagram to ensure proper wire and connector placement.
  • From there, lay your wiring harness to help you know the length to cut and how to route. Here, you may use the old harness you want to replace to make it easier.
  • Then, determine your fuse box installation location at the end of the harness to minimize any potential damage.
  • Now, lay your wires on your workbench according to your wiring diagram and mark them appropriately.
  • In this step, you may get old connectors from the old wiring or buy new ones and ensure they match.
  • You may now strip about an inch of each wire in your harness ready for the connector installation.
  • When through, put heat shrink tubings over each of your wires before the connector installation
  • Now attach connectors to your wires and crimp them, ensuring they are tight to avoid coming off.
  • Lastly, roll over the heat shrink tubing to your harness joint and pass a heat gun to secure it.
  • You may now install your harness to your car following the wiring diagram. 
Installing a DIY harness

Installing a DIY harness


While you can use my research to create and install your wiring harness, ensure you test it first before application. In addition, ensure it follows the safety standards of your area, lest you get into issues with the authorities.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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