For many car audio systems, a big 3 upgrade can vastly improve your vehicle’s electrical system. Amplifiers, subwoofers, speakers, and other components pull power and can stress your electrical components. For example, many with car audio systems may notice their headlights dimming or their windows rolling down slower than usual. These are telltale signs that a big 3 upgrade is needed. 

A big 3 upgrade will allow more current flow to all of your stereo components, improving your electrical system by ensuring more consistent voltage. This upgrade entails replacing the three main cables in your electrical system with 4 gauge or 1/0 wires.  

Let’s take a look at what those three cables are and how to install a big 3 upgrade!

Required Tools (may vary depending on vehicle):

  • Wrenches
  • Sockets & Socket Extensions
  • Ratchets
  • Zip Ties
  • Crimpers
  • Big 3 Upgrade Kit


Make sure to disconnect the negative battery terminal

IMPORTANT: Before starting, disconnect the negative terminal off of your battery to prevent shorting out or damaging any electrical components.

1. Install the Charging Wire from the Alternator to the Battery Positive Terminal

First, locate your alternator. Some vehicles will have covers that may need to be removed in order to get a better view of the alternator and wiring. Once located, look for the power wire that is running from the alternator to the battery or fuse box. Connect your new wire to that same post, leaving the existing wire on as well.

If desired, wrap the wire in Tesa tape. Next, route your newly connected wire to the battery’s positive terminal. Secure the wire to the battery and add zip ties to keep the install clean.

2. Install the Chassis Ground Wire to the Negative Battery Terminal

Decide on where you want your ground wire to attach to the chassis. If a solid, bare metal area is not readily available or ideal, you can drill your own hole in the chassis and use your own stainless steel nut and bolt to attach the wire. You may need to also need a wire wheel to scrape the paint off, making the metal bare.

Once decided, connect your new ground wire to the negative battery terminal and secure it in place. Route the wire to your new grounding point on the chassis and secure it. 

Charging wire hooked up to the alternator

3. Install the Ground Wire from the Engine Block to the Chassis

Locate your OEM ground wire on the engine block and follow it to the chassis. The location of this will vary from car to car. Remove your OEM ground wire and clean up the existing connection points if they look like they need it. From there, connect your new wire to the engine block and chassis securely. 

Once all three of your new wires have been installed as described, your big 3 upgrade is complete! This new wiring will improve your electrical system’s handling of the current flow to your stereo components. In turn, you should be able to eliminate or minimize the common systems of a stressed electrical system.

Our team at Sonic Electronix has also created a great step by step video of this process. Check out the YouTube video below to follow along and contact us with any installation questions!

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