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HomeTips & GuidesWiring Upgrade – An Essential Checklist in Maximising Car System

Wiring Upgrade – An Essential Checklist in Maximising Car System

About Wiring Upgrade: Have you ever considered upgrading your car system to an even more optimal level? Generally, a wiring upgrade involves enhancing or replacing three main wires in your vehicle to increase current flow efficiency and electrical conductivity. 

In the world of wiring harnesses, we often refer to the process as the Big Three wiring upgrade. 

Stick around as we uncover the advantages of a wiring upgrade and a step-wise guide on conducting the procedure. 

Why wiring upgrade?

Normally, the charging and factory-wiring car systems fulfill basic requirements. As such, you can overwhelm the system when you integrate aftermarket electronics such as high-powered amplifiers. Consequently, your car may have alternator/battery damage, voltage drops, or dimming headlights. For these reasons, you should consider a wiring upgrade. 

Comparison between a healthy and broken car alternator

(Comparison between a healthy and broken car alternator)

An upgrade in your car’s electrical system is essential for several reasons. Some include:

  • Longevity: First, when you upgrade your system, you ensure a more consistent current flow. Ultimately, it prevents premature malfunction of your car’s delicate electronic elements.
  • Cost-effectiveness: Revamping the electrical system reduces tension on the charging system. This improves gas mileage, saving money on fuel purchases. 
  • Optimum sound quality: A wiring upgrade reduces noise interference to your car audio by blocking the noise from other components. 
  • Elevated resale value: If you’re considering selling your car later, consider upgrading it to increase its value. 
A dealer selling a car

 (A dealer selling a car)

What wiring harnesses are generally upgraded with a wiring upgrade?

In this section, we will discuss the three crucial wiring harnesses in a vehicle’s electrical system: the positive alternator, engine block ground, and battery ground wires. Collectively, when paired with large gauge cables, they improve current flow and reduce resistance. 

In-depth explanation

  • The chassis ground cable runs to your car’s engine block.
  • Then, the negative battery wire runs to the car’s chassis from the battery.
  • Lastly, the alternator positive cable goes to the battery’s positive terminal. 

High-output alternator

The alternator offers extra power to the battery, thus enabling it to withstand heavy loads while maintaining optimal voltage levels. In addition, it allows the battery to charge faster. 

Key components and materials needed for wiring upgrade

A toolbox

 (A toolbox)

A Big 3 upgrade kit comes with all the tools you need to modify, save for some exotic/standard tools. 

The table below summarizes the basic tools needed and their features/quantity.

Tools Features
Standard tools (Screwdrivers, wrenches)
Heat gun
Wire strippers Sufficient size
Crimpers Sufficient size
Soldering iron and solder
Zip ties (Plastic cable ties)
Wire cutters Sufficient size
Terminals that are ideal for battery postsTwo
Lugs/Ring terminals suitable for the cable 
Heat shrink tubing ⅝” or smaller 
High-capacity power cable 4AWG

How do I perform a wiring upgrade?

There are some factors and precautions to consider before performing a wiring upgrade. For instance, ensure you’ve turned off the engine and parked safely away from harsh weather conditions. 

Additionally, you should carry out the procedure before incorporating the high-output alternator. 


Prepare your cables

From our experience, we’ve found that the three upgrading wires use 1/0 AWG cable. But, this length will differ depending on the car’s demands. If unsure of the cable length, take some measurements, overestimate its purchase, or consult your local dealership.

Remember, never use solid core wire. Instead, a 4 AWG or higher high-strand count cable will be ideal.

An electrician checking, repairing, and upgrading wiring

 (An electrician checking, repairing, and upgrading wiring)

Once you get the cables, get the length of the vehicle’s factory cables. Then, cut the new wire about 1-to-1.5 inches longer than the factory wires.

You can also retain the factory cables to increase protection against continuous bending and vibrations as the car moves.

Choose the path for cables, then cap them.

When choosing a good path for your wire to run, ensure it’s far away from surfaces that heat up, such as the engine block, moving parts, fans and belts.

Next, put a cap at the end of each new cable. Afterward, slide the wire into a wire lug. Then, get your solder and melt the cable strands without interfering with the cable. 

Finish up by weatherproofing and sealing the ends of new wire connectors with heat shrink tubing. 

Using heat shrink tubing on a cable

(Using heat shrink tubing on a cable)

Disengage the electrical equipment.

Here, you’ll disconnect your battery’s negative and positive cable. In the process, confirm that you’ve disconnected additional batteries and capacitors in the electrical system. 

Connect the cables

While the sequence doesn’t matter, we often connect the battery negative, positive, and the grounding cable. You may run the new cables alongside the factory ones in all these connections. Alternatively, you can drill new holes into the chassis and then make the connection. 

Firmly secure the wiring.

Secure your newly connected wires using the cable zip ties to prevent unnecessary movement.

Cable wiring fastened by plastic zip ties

(Cable wiring fastened by plastic zip ties)

Examine the final product.

If you’ve followed all the instructions in the letter, your new electrical system should be good to go. Moreover, you can use a digital multimeter to measure the new cables’ resistance before you connect the negative battery cable. 


Now that you’ve gone through the basics of the wiring upgrade, we hope the steps you take onwards will be easy. 

Consult our expert team if you need more help with wiring and cable products. 

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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