Unlock Advanced Control with the Holley J4 Harness

The Holley EFI 558-404 J4 auxiliary harness is the key to unlocking the full potential of your Dominator EFI system. Designed for users who need to add custom sensors, switches, or additional outputs, this harness provides the necessary connection points to expand your engine management capabilities. Whether you are adding nitrous control, boost solenoids, or custom data logging sensors, the J4 harness is your foundation.

Advanced Features for Custom Builds

• Dominator Compatibility: Specifically engineered for the J4 port on Holley Dominator ECUs.
• Expandable I/O: Provides easy access to auxiliary inputs and outputs for complex tuning setups.
• High-Quality Wiring: Constructed with automotive-grade wire and sealed connectors to ensure long-term durability in high-vibration environments.
• Customization Ready: Allows for a clean, professional installation of aftermarket sensors and control devices.

Using the 558-404 harness allows you to maintain a tidy engine bay while adding sophisticated control features to your vehicle. By utilizing the factory-specified J4 port, you ensure that your added components are integrated properly into the ECU software, allowing for seamless configuration within the Holley EFI software suite. For serious tuners and performance builders, this harness is an indispensable tool for advanced engine management. Experience superior technical support and high-quality parts for your next project at GGCRACING.