Custom Wiring Harness

  • For over ten years of experience as a leading custom wiring harness manufacturer,
  • we have been providing excellent custom products and services to our clients.
  • Skyrocket Your Business With Professional Wiring Harness Manufacturer You Can Definitely Trust.

1,000+ Customers Over The World

After ten years of powering subjects, we’ve fine-tuned the custom wiring loom services and are committed to helping you simplify your workflow, launch faster, and make your business boom.
wiring harness

What We Can Do​

We provide various prototyping and manufacturing services to support our customers’ individual needs. Fully-automated production equipment has largely shortened production time.

The Best Custom Wiring Harness Manufacturer

The custom wire harness is built according to the customer detailed specification and our professional standard. Each step is monitored and goods will be strictly tested before each shipment.

custom wiring harness manufacturers


Make prototypes

According to your drawing or spec sheet;

Ensure The Quality

UL, ISO9001, 14001, 18001, IATF16949 System Management.


The better source of MOLEX, JST, TE, DUPONG, HIROSE.

Removed harness showing colorful wires

Deal With Your Cases

Skillful foreign trade staff to deal with your cases to save your energy.

Cross-Section Analysis

All the terminal crimping passed Cross-section analysis;

OQC Dept

100% Tested online and IEC spot testing at OQC Dept.

Custom Wiring Harness Guide

READY to start customizing your harness?
Free download the Custom Wiring Harness​ guide.

Wiring Harness: The Ultimate Custom Guide

Exclusive Bonus:Need a custom harness? Contact our support team today to get started  Quick click>>

Has it been quite hard for you to make a custom wiring harness for your wiring project?

Do you want the expert’s knowledge on making a good custom wiring harness?

Just one read of this article will make you a professional wire harness designer.

We’ve covered extensively in this article all you need to know about wiring harness, the components required for a successful cable harness design and a step-by-step guide on how to make a custom wiring harness for your trailer, car stereo, and engine.

Get ready to become a professional custom cable harness designer.

Custom Wiring Harness

CHAPTER 1: Everything you should know about a Wiring Harness

 A wiring harness is a systematic bound of electric wires, which send signal and power to different points in an electrical system. The bounding of these electric cables is done using straps, electronic tapes, wire lacing and so on.

A wiring harness is always designed according to the application or the specifications of the electric system in which it’s needed. Over the years, there have been several developments and uses of cable harness.

The following industry uses a lot of wire harnesses for their solutions, this includes:

  • Automotive,
  • Medical,
  • Telecommunications,
  • Acoustic,
  • Military and Electronics.

All these industries have specific needs, based on the designs, environment, electrical load and so on, therefore, there is a need to make custom cable harness designs for every application.

Instead of connecting different cables through different points in an electric system, a cable harness can only be designed for the system.

The advantages of using a wire harness over loose cables are numerous;

  • reduced installation time;
  • optimum space management;
  • easy maintenance;
  • prevention of short circuit, and security from effects like vibrations, moisture, and abrasions.

With all these in mind, let’s start our journey of helping you make your custom wiring harness.

What are the things you need??

CHAPTER 2: Things you need to make your custom Wiring Harness

 Before making your custom wiring harness, the first and most important thing to have is a design or wiring diagram.

This diagram is what will lead you to measure wires, cutting and stripping wires, bounding the cables, etc. In the next chapter, we’d look much more into using the wiring harness diagrams.

Asides the diagram, the following tools are needed in making a wiring harness.

  1. Wire Cutter: used to cut the wires;
  2. Wire Stripper: used to strip off some part of the insulation of a cable;
  3. Crimping Plier/Ratcheting Crimpers: used to tighten the terminals to the stripped wires;
  4. Heat Gun: uses high temperature to shrink the covering plastic tubes to the body of the cable;
  5. Multimeter: used to test for continuity and other parameters within the wiring connection;
  6. Heat shrink: a soft plastic used as a covering for connection joints;
  7. Wires: connecting wires for the flow of signal/power from the source to the needed terminal;
  8. Terminals: a plastic body with a conducting head that makes contact with the bare/stripped wire;
  9. Zip Ties: used to bundle the wire harnesses neatly.

This equipment varies on a large scale production of wiring harnesses.

There are now fully automated machines that take care of the whole process from the wire cutting, stripping, crimping and joining terminals, etc.

These machines have correct and efficient outputs, ensuring there are no loose ends or short circuit.

That’s why we at Cloom use the fully automated machines for all our custom wiring harness.

Like I said earlier, to make your custom wiring harness, you must first have a circuit diagram.

Let’s look in details, why and how to use one.

CHAPTER 3: How to use a wiring harness diagram?

 The circuit design/diagram is very foundational to make a custom wiring harness successfully.

Everything you have to customize in your cable harness comes from a well-designed wiring diagram.

Please note, the wiring diagram is entirely different from a schematic diagram.

A wiring diagram gives a physical layout of the connection, unlike the schematic diagram.

However, it also makes use of abstract symbols to represent some components.

You can tell from the wiring harness diagram how complicated or how pure your custom wire harness would be.

Ideally, every cable harness circuit diagram will have the following;

  • Symbolized components,
  • Optimum positioning,
  • Splice positions, and Wire colours.

Whatever you see on the wiring harness diagram is a representation of what and how the wire bundling will look.

If you don’t have a wiring diagram, you would need to consult an expert to design the perfect wiring diagram for your application.

This video would be a helpful link:

Once you’ve got the wiring diagram and components ready, these are the possible types of harnesses you might be making, so take note to identify it.

CHAPTER 4: Types of Wiring Harness

 Two major factors determine the type of wire harness to make.

Firstly, the application, secondly, the environment. Based on these two factors, there are 3 types of cable harness that you can make.

They include:

Open Bundle:

in this type of wiring harness, the cables are attached to the connectors and lugs and are coupled in bundles with various breakouts using plastic tie wraps or waxed lacing twine.

Closed Bundle:

Wires are bundled with a covering, such as pulled-on braided tubing, braided-on Nomex or nylon, or in some cases, metal braid.

Waterproof harnesses:

Legs are covered with tubing, such as neoprene. The junctions between the legs and backshells of the connectors are molded with a material such as urethane or rubber compounds.

In some cases, PVC tubing and molding are used.

Curled from CONNECTOR SPECIFIER magazine.

Enough of theory, let’s get our hands on, you can follow the instructions below and the shared links to customize your trailer, car stereo, and engine harness.

CHAPTER 5: How to custom Trailer Wiring Harness?


Step 1:

To make a custom trailer wiring harness, you first have to come up with an intended design based on the geometric and electrical requirements of a trailer. This design should be represented on paper so you can easily refer to it.

Step 2:

After putting down the design, you cut the wires into desired lengths using a wire-cutting machine/cutter.

Step 3:

When making the design of a custom trailer wiring harness which would usually be fixed on a towing vehicle, you have to consider the requirements of the trailer; This includes powering the operating lights on the container which are the turn, tail, stop, park and brake lights and other electrical parts of the trailer depending on the trailer. Take note of this process mentioned to ensure the towing vehicle is in total control of the electrical elements of the container.

Step 4:

When purchasing wires to use for a custom trailer wiring harness, you have to ensure your cables can withstand fire, abrasion, vibrations, corrosion and extreme temperatures. One way to ensure this is by getting heat-shrink collars galvanized wire clips to make the wires firm and straps to pack the cables together.

Step 5:

After knowing the electrical requirements of the trailer and getting suitable wires, the next thing is to make the connections to the guiding lights ensuring you work on one view (circuit) at a time. Connect connectors on one end of the wiring harness to the part designed for it on the towing vehicle and the other purpose to the trailer lights accordingly.

Step 6:

After making all the necessary connections, you then tidy up the wires using the clips, collars and straps talked about earlier so that the cables don’t just dangle around when driving. The most advisable is to tape the wires together using the straps to hold it in one place.

Step 7:

Put your wiring harness to test. If you encounter any problems, you can refer to this video to troubleshoot it.

Let’s move on to car stereos.

CHAPTER 6: How to make custom Stereo Wiring Harness?

 The function of a stereo wiring harness is to transmit audio signals.

Step 1

To make a custom wiring harness for a stereo, you have to consider the stereo port and pins in it. Check the pins in it and find out the function of each of the nails; This varies from stereo to stereo, so it’s best if you search for your particular radio on the internet to know each pin’s functions.

Step 2

After getting this, then you get wires suitable for audio transmission. The quantity of cable you will get depends on the number of pins in the port and the distance over which the wiring harness is meant to connect.

Step 3

Then you get a connector which has pins that match the stereo’s port. Solder the wires accordingly to these pins ensuring that the pins don’t touch each other in the process; This can be achieved by insulating each connection with a piece of heat shrink.

Step 4

After soldering wires to all the pins required successfully, the next thing is to get female A/V jacks. These can be obtained from electrical stores. Solder the wires to the female A/V cords accordingly taking note that the outside metal of the A/V jack is harmful while the inside is positive.

Step 5

After this, use a multimeter to ensure that all the connections are right and connected.

Step 6

After ensuring the connections are correct and working, make the relationships strong and durable by melting the plastic on each link using a glue gun. After this, recheck the connections to see if they are working with the multimeter.

Step 7

Lastly, bind the wire together using wire straps to make it firm and neat. Your custom stereo wiring harness is ready.

Step 8

Put your wiring harness to test. If you encounter any problems, you can refer to  this video to troubleshoot it.

To the last DIY project, the engine wiring harness; This can be quite tasking though, but we believe in you.

CHAPTER 7: How to make custom Engine Wiring Harness?

 Making a custom engine wiring harness depends on the engine in question and the function it’s to perform;This would determine the structure of the wiring harness.

Step 1

Highlight the function of the wiring harness in the engine. It’s essential to draw out a plan then and list out the parts and materials needed.

The wire specifications would also depend on the engine and the function the wiring harness is to perform.

Step 2

Basically, for engine wiring, relays are always used. You start by attaching the wires to the relay accordingly. After wiring the relays, you mount the relays and then create a switch and route the switch harness from the relay to the switch location accordingly.

Step 3

After making the switch connections, route the wiring towards the engine part and also make the connections there accordingly.

Step 4

After all the connections have been made, ensure the connections working using a continuity checker.

Step 5

After this, tape the wiring together to make it firm and stable; This can be achieved via various means like using wire straps or electrical straps. After taping them together, secure the wiring harness away from moving engine parts.

Step 6

Put your wiring harness to test, and if you encounter any problems, you can refer to this video to troubleshoot it.

Clear, right?

If you bother to know, this is how our experts at Cloom make the customwiring harness solutions to companies all over the world.

CHAPTER 8: How we Custom Wiring Harness in Cloom?

 To customize a wiring harness to suit your applications, our design experts follow the following steps meticulously.
  1. We understand the specifics of your system and applications of the wiring harness to be made; This will help us determine the type of wires, kind of insulation, connectors to use, and so on.
  2. We get your detailed circuit drawing for the electric system to be wired. Our design experts can also make a professional wiring circuit drawing for you.
  3. Using state of the art equipment and technical expertise, we design a prototype set of wire harnesses for your desired system, to suit the applications, resistance, and all other specifics.
  4. We test the accuracy, efficiency, and functions of the cable harness with the aid of a state-of-the-art test board.
    This way, only A+ solutions are produced for any application you might need.

Cloom, your most reliable wire harness and cable assemblies manufacturer, has professional expertise and latest technologies for offering excellent custom wiring harness.

We have more than adequate experience in Electronics wiring harnesses, Power cables, Signal wiring harness, and Automobile wiring harnesses.


 Worth the read, right? We hope you can now boldly say I’m a wiring harness professional.

You can send us an inquiry for the custom wiring harness you need and we’d reach you promptly.

Hey, I am John, General manager of Cloom and OurPCB.

I am a responsible, intelligent and experienced business professional with an extensive background in the electronics industry.

Reach me at to get a quote for your projects.


Fill in your details and we’ll get back to you in 24 Hours.

Need Custom wiring harness?

I’m Here To Assist You

Assembly work is boring for you?

Feel free to contact me, and I will be more than happy to answer all of your questions.