Rated 4.9 Stars based on 6,700 reviews
Fast Delivery
Customized Service
HomeTips & GuidesReplacement Wiring Harness: Quick Steps to Repair a Broken Wire

Replacement Wiring Harness: Quick Steps to Repair a Broken Wire

Here is a replacement wiring harness guide to help you fix your car’s electricals. 

Once in a while, your car’s electrical system may glitch, resulting in the wiring harness melting. Although this issue may seem trivial, it can become a massive problem if left unaddressed. That is why today we are sharing insights on replacing your wiring harness. 

How does an Automotive Wire Harness get Damaged?

Automotive wire harnesses and the cables inside them are exposed to rough conditions that may prompt them to be damaged. 

  • For instance, when driving on weather roads, electrical cables next to the engine are subjected to immense vibrations. 
  • Also, so much heat, especially in the engine chamber, can scorch the wiring harness. 
  • If you live in coastal regions with salty water bodies, you are subject to immense salt saturation. The salt ultimately finds its way to your car’s interiors, which is also not great for harnesses. 
  • Another damaging thing is rainwater. When you drive in the rain, water will contact the car’s interiors. Rainwater combined with salt will induce corrosion of wires, ultimately damaging them. 

Prior Considerations Before Automotive Wiring Harness Replacement

Cables in an engine control unit. 

Cables in an engine control unit. 

The wiring harness’s structure is complex, but everything is a breeze considering the following aspects.  

Always be safe

Unplugging a car battery. 

Unplugging a car battery. 

When performing any car electrical repair/replacement job, the rule is to disengage the battery first. This will prevent electrical shocks because the battery is the car’s power source. 

Only connect the battery when you’re doing diagnostic steps. Most importantly, ensure that you’re careful not to touch any naked part with bare hands. Also, check out for charred/exposed wires and avoid touching them while the battery is still connected. 

Understand the Circuit

Electrical wiring in a car. 

Electrical wiring in a car. 

If you are not an electrical systems expert, we recommend hiring a mechanic to replace the harness. Modern vehicle circuitry is complex and delicate. 

For example, you can solder a wire and cause a signal error, especially when you overdo it. Also, a seemingly innocuous act, such as splicing a wire, can increase resistance. It will undoubtedly affect its conducting capacity. 

In addition, be gentle when removing wires from the harness. It will ensure that the cable’s connectors are intact so you can reuse them. 

Get the Wire Gauge Right

You cannot replace a wire with a thick gauge profile with a thinner one. Such an act can lead to a surge, which can scorch the entire wiring. So, using a wire gauge similar to the one you’re replacing is always best. 

Specifically, ensure that the wire gauge matches the application. For instance, if you’re replacing a battery cable, you must go for a thick wire, as such a cable carries a lot of voltage. In addition, you must also use the correct wire length. 

A longer wire than necessary will introduce current flow resistance, especially if you don’t consider increasing its thickness. Finally, we advise you to refrain from using a solid core cable. In the short term, it will be great, but you cannot bank on it, especially if you drive on rough roads. 

Select the Perfect Connector Size

Components for electrical installations in a car. 

Components for electrical installations in a car. 

Connectors can break your circuit, so you should be very careful about their sizes. If they’re too big, you can be sure the connection will be loose, a recipe for wiring failure. Small connectors are also problematic; you must strip wires for a perfect fit. 

Once you have set up the connectors, a heat shrink tubing cover will help secure the connection. It also shields the wires from dirt and moisture, which can damage them. We advise that you avoid quick connector kits to mend broken wires in the harness. 

Despite their convenience and ease of installation, they are quick fixes that cannot offer long-term service. Another thing you should avoid is using electrical tape to mend wires and twists on connectors. 

How to Replace a Broken Wiring Harness

New Wires. 

New Wires. 

Start by assembling the necessary tools and materials for the replacement job. You will need the following:

  • New electrical wires of the same gauge as the one you’re repairing. 
  • Wire crimping tool
  • A heat shrink tubing
  • Several butt splices
  • A lighter 
  • Wire loom

Next, follow the steps below: 

  • Start by disconnecting the battery connection. However, you will need a power connection using a diagnostic tool to identify the faulty wire. All you have to do is work with caution to avoid accidents. 
  • Next, ensure you have a replacement wire with a gauge matching the wire you’re repairing. Now, strip the new wire’s ends to expose the conducting part you’ll need to connect to the wiring system. 
  • Remove the damaged cable by cutting it off with your wire cutter. Ensure the remaining wire has ends you can strip to expose the conductor. 
  • Now insert a but splice on the old wire, insert the new wire, and cover it with heat shrink tubing. Heat the tubing to provide insulation over the connection you have just made. Repeat this process on the other end of the wire. Insert the wire loom, and you’re good to test the connection. 


Do not ignore a broken wire in the harness, as it could cause a massive problem to the electrical system. Luckily, most electrical repairs are simple DIY jobs you can do in the comfort of your garage. Set everything as advised above and restore your car’s electricals to the best shape. 

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.

Background media

For Better Future
and Business
Let’s Talk Now!

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

Contact Form Demo


[email protected]




3rd Floor, Nanhai Plaza, NO.505 Xinhua Road Xinhua District,
Shijiazhuang, Hebei, China. 050057


© 2007- 2023 Cloom tech. ALL RIGHTS RESERVED.



Subscribe to our newsletter for the latest updates, exclusive offers, and exciting news delivered straight to your inbox.