Wiring has always been one of the most intimidating parts of a Honda K-Series swap. Even today, many builds rely on 20-year-old factory engine harnesses with unknown histories, previous repairs, damaged connectors, and brittle wiring.
That's why we developed the Hybrid Racing Tucked K-Swap Engine Harness - a brand-new engine harness designed specifically for K20 and K24 swaps.
Why Build a New K-Series Engine Harness?
For years, the standard solution has been to start with an OEM 2002–2004 RSX engine harness and modify it as needed for your swap.
That works, but those original harnesses are now more than two decades old.
Our goal was to create a modern replacement that keeps what we like about Honda's original wiring while adding cleaner routing, better flexibility for different K-Series combinations, and completely new components.
The result is a harness built around the proven 2002–2004 RSX/K20A2 wiring configuration, making it compatible with many of the K-swap components and ECU solutions already on the market.
OEM-Style Wiring Without the Old Harness
One of the most important features is something you might not notice right away: we use OEM Honda wire colors.
That means if you're diagnosing a problem using a Honda service manual or wiring diagram, the wire colors and stripe patterns correspond with the original Honda circuits.
If you've ever tried troubleshooting an aftermarket harness where every wire is a different color from the factory diagram, this can make a huge difference.
We also machine-test every completed harness pin-to-pin before it leaves our facility, checking for incorrect connections, open circuits, and shorts.
Designed for K20 and K24 Swaps
K-Series swaps rarely use every component from one donor car anymore.
It's common to combine a K24 engine with K20 electronics, different injectors, another transmission, and an aftermarket ECU.
We designed the harness with that flexibility in mind.
The harness includes removable injector and vehicle speed sensor adapters along with connectors for K24 crank and knock sensors. This allows you to configure the harness for different combinations without cutting into the main engine harness.
We've also incorporated three spare circuits through the C101 connector, giving builders room for additional sensors or equipment later.
Cleaner, Tucked Routing
The harness isn't just designed to work better; it also cleans up the engine bay.
We've adjusted the branch locations and routing to create a more tucked appearance while still using factory mounting locations wherever possible.
Properly securing the harness is about more than appearance. Keeping wiring away from moving components and preventing it from rubbing against the engine or chassis helps protect it from long-term wear.
Engine Harness vs. Conversion Harness
This is an engine harness, not a chassis conversion harness.
The engine harness connects components like your injectors, ignition coils, sensors, alternator, and ECU.
In most K-swapped Hondas, you'll still need a K-Swap Conversion Harness to connect the DC5-style engine wiring to the factory wiring in your chassis.
The two harnesses perform different jobs but work together to create a complete K-swap wiring solution.
Know Your Combination
K-Series compatibility can get complicated quickly, so engine code alone isn't enough to determine whether a harness will work.
Your engine, crank and knock sensors, injectors, transmission and VSS, throttle body, ECU, and chassis wiring all need to be considered together.
Our Tucked K-Swap Engine Harness is designed for drive-by-cable applications using compatible K20/K24 components and a wideband ECU configuration. It is not intended for drive-by-wire engines, K20C engines, or direct-injected K24 applications.
If you're unsure about your combination, our technical support team can help verify exactly what you'll need before you order.
Built for the Next Generation of K-Swaps
The Honda K-Series platform has now been around for more than 20 years, but the cars we're building with these engines aren't slowing down.
We wanted an engine harness that offered the reliability of new wiring, the serviceability of Honda's original design, and the flexibility needed for the way K-swaps are actually being built today.
Whether you're refreshing an older K-swapped car or starting a completely new build, the Hybrid Racing Tucked K-Swap Engine Harness gives you a clean, tested, and purpose-built alternative to relying on another 20-year-old factory harness.