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HomeTips & GuidesRewire a Wire Harness: When it comes to car wire harness installation?

Rewire a Wire Harness: When it comes to car wire harness installation?

About Rewire a Wire Harness, Harnessing is not as complicated as it looks at first glance. If it’s your first time, starting the installation process will be pretty confusing and daring work for you.

After all, it’s not just about changing the old components with the new and shiny parts. 

As a newbie, it may seem like you have to be familiar with every type of mechanism happening in the wire.

But in reality, experts also take time to analyze and then work on specific harnesses. The work has to be done with mindfulness so there is less chance of mistakes. 

In this article, we will explain the process in simple steps that you can work with. Let’s look into the details.

Table of Contents

How to rewire a wire harness in a car?

Installing a new wire may not be as complicated as working with the rewiring of the harness. But, if you follow the below steps, things will get pretty much easy for you.

Step 1: Buy the Required Wire Harness

First, you must see which part of the car requires the rewiring. Since every part has its own specifications, you will need specific components for each. To start, look into the number of circuits a part needs.

Usually, vehicles with minimum wiring need a 12-circuit wire harness. These can be a Model hot rod or a T-bucket because these vehicles only have a few functions that need current supply, such as ignition, lights, horn system etc.

You can get these circuits with a cloth covering that is best for old cars. 

For modern cars, however, things have changed, and thus they require much more complex circuitry. Now you have to support the basic as well as additional features like audio, air conditioning, automatic window and EFI

These automobiles need 18 to 21-circuit harnesses with a wide range of covered wiring to attach all the components simultaneously. If the requirement exceeds that, you can also go for the 28-circuit wiring harness.

Step 2: Prepare the Tools

The appropriate tool collection will make a huge difference in the installation; one of the important components is the crimping tool, which will connect the wires to each other and regulate the current supply.

A wire stripper is also necessary and comes in auto or manual variations. The better the stripper is, the cleaner the wire will be after stripping. 

On top of that, don’t forget the quality connectors that will link all the wires at the end. Go for what works in the industry, and don’t buy rare types of connectors since their usage will be difficult for you.

For a clean and professional finish, you can use heat shrink tubing on the terminal of the wires. It will add an extra layer of protection over the links, making them difficult to break. 

Other protections can be nylon braiding, cloth braiding, plastic split loom and others. OEM holders for wires can also be a great choice to secure the wire bundles on the walls. Additionally, insulated clamps can also work in place of retainers. 

Step 3: Start with Wiring Harness Installation

Start by placing the whole harness on the ground and taking a look. That way, you will have a whole picture of the structure and where the connectors should go.

Now, take the group of wires for one function of the car. For example, if you want to connect the studio V wires first, pick the circuit and see how it will connect in the manual.

If there are any extra ties, feel free to cut them and arrange the wires according to your vehicle’s needs. Also, you can use sacrificial ties for the bundling.

Step 4: Connect the Fuse Block

The fuse block is the starting point of any harness wire, so it is important to connect it carefully. For that, you will take the box and fix it to the bracket or body of the car.

Typically, you can find these boxes under the dashboards or seats. But, for your vehicle, you should connect it where you see it fit. 

As a rule of thumb, it should be placed in an easily accessible place so that cables can easily run back and forth in the car.

Also, if you are replacing the old wiring, don’t forget to keep its picture in mind and there are useful components that may help you in your new process.

Step 5: Route the Wires and Finish the Harness Connection

As the fuse box is installed, run the wires from it to their respective endpoints. As you are routing them, you will see the wires passing through the metal components. To avoid any type of EMI or cuts, make sure to use Rubber Grommets on them.

Wiring harness kits usually have the templates to cut through these metals. So, for such cases you can also refer to the booklet and make the installation process efficient. 

Packing wire harness in production line

Caption: Packing wire harness in production line

What Does It Cost to Rewire a Wire Harness?

Installing a custom wire harness in your car is a pretty hectic job – if you hire a professional to do it from scratch. It will easily take 30-40 hours, and as the rates are around a hundred bucks, you can see yourself drowning in debt.

If you buy a professional kit with a pre-assembled harness and tools, the installation process labor reduces to half what it is.  

Car Electric Wire set

Caption: Car Electric Wire set

Advantage of Kitted Wires

  • These kits have already cut, terminated and labeled wires that eliminate the cutting and stripping process. With the reduced labor for installation, you will assemble all the stuff quickly. 
  • Wiring harness manufacturers also give you the choice to select what type of harness you need. You can decide the features based on the type of wire, connectors or simply personal preference.
  • Kitted wires eliminate the extra work of wire cutting, stripping and termination while you focus on the installation itself only. With that, you don’t need to have extra tools on your hand that will only be a waste of time and money.
  •  The real advantage will be when you are working on a larger scale. There, you will see that ordering in bulk saves you so much time and money. Also, this will help you reduce the cost of your product overall, making it economical for the customers. If you need different types of harnesses in a product, you can just order them in one place and lessen the administrative work as well.


Wiring kits can be very handy if you are keen on “do it yourself,” especially regarding the wiring harness kits at Cloom

Our harnesses include wires of different lengths and specs so that you can choose what your system needs. Also, you can customize the kits according to the needs of your vehicle whilst keeping the quality of the product intact. 

Moreover, every cable in the kit is labeled for specific use to simplify the identification. These labels also mention the functionality, CAGE code, connecting points and other details.

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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