Rywire Fuse and Relay Center

Rywire Mil-Spec Fuse & Relay Centers: Race-Engineered Power Management

When you're building a dedicated race car or performing an engine swap, managing your electrical system cleanly and reliably is just as important as the engine itself. Rywire Motorsports Electronics brings the same military-specification build philosophy that defines their engine harness lineup directly into their Fuse and Relay Centers — delivering a compact, purpose-built power management solution trusted by engine swap enthusiasts and competitive racers alike.

Built for Standalone Race Applications

Rywire's Mil-Spec Fuse/Relay Box Sub-Harness was engineered specifically for race cars running an engine-only (standalone) configuration. Rather than fighting with a full OEM chassis harness, builders can use this sub-harness to cleanly power all critical engine functions through a single, organized hub. The unit houses five relays and fuses covering the core circuits any swapped or stripped-down build demands.

• Five dedicated relay and fuse circuits for computer, fan, fuel, starter, and O2 sensor functions
• 4-pin DTP connector for fuel pump, fan, spare output, and switched output — simplifying hookup to critical accessories
• Flying lead connectors for fan and fuel pump wires, plus an optional flying lead harness for gauge cluster functions
• Auxiliary relay usable for electric water pumps, additional lighting, or other accessory loads
• Compatible with Rywire's Mil-Spec Switch Panel for a fully integrated, clean cockpit build

Engine-Series Specific Fitment

Rywire offers their Fuse/Relay Box in variants tailored to different engine families. The K-Series version includes a prewired Computer “E” plug, a C101 plug-and-play engine harness connector, and a primary 4-wire O2 sensor plug — making it a true drop-in solution for builds using OEM 02-04 RSX or EP3 harnesses in any chassis. The Universal (B/D/H-Series) version is designed for Rywire's own B, D, and H-Series harnesses, with a straightforward installation that requires only connecting wires to the fan, fuel pump power, and ignition switch.

Rywire also accommodates custom integration needs: engine harness pin-out and connector mates can be sourced directly, and the fuse/relay box can be adapted for AEM Infinity harness builds, S2000 conversions, 2JZ swaps, and other Rywire harness configurations upon request.

Why Rywire for Fuse & Relay Centers?

Rywire Motorsports Electronics has spent decades specializing in high-performance and Mil-Spec wiring solutions, supporting some of the fastest purpose-built race cars in the world. Their fuse and relay centers reflect this heritage — built with the same attention to connector quality, wire gauge, and system reliability that defines their full harness lineup. For builders who want a clean, race-ready electrical system that integrates seamlessly with a Rywire engine harness, their Mil-Spec Fuse/Relay Box is the natural companion piece.

Browse the complete Rywire brand catalog to explore their full range of engine harnesses, adapters, and electrical components, or view all Fuse and Relay Centers to compare options across top motorsport brands.