Holley EFI Terminator X & X Max Input/Output Harness – 8 Pin
558-462
The Holley EFI Terminator X & X Max Input/Output Harness – 8 Pin expands the capabilities of your Holley EFI engine management system by providing full access to all available ECU inputs and outputs. This auxiliary harness is designed for Terminator X and Terminator X Max ECUs, offering four programmable inputs and four programmable outputs for integrating additional sensors, switches, relays, and accessories.
This 36-inch harness features pre-terminated flying leads, a sealed ECU connector, and all eight terminals populated. While some Terminator X kits include only a three-wire I/O harness, this upgraded harness unlocks the ECU's complete I/O functionality, making it ideal for advanced EFI installations and custom vehicle builds.
Includes:
- (1) Holley EFI Terminator X & X Max Input/Output Harness
- Sealed 8-Pin ECU Connector
- Eight Pre-Terminated Flying Leads
Specifications
| Specification | Details |
|---|---|
| Manufacturer | Holley EFI |
| Part Number | 558-462 |
| Product Type | Auxiliary Input/Output Harness |
| Harness Type | Auxiliary |
| Compatible ECU | Terminator X and Terminator X Max |
| Inputs | 4 Programmable Inputs |
| Outputs | 4 Programmable Outputs |
| Wire Quantity | 8 |
| Wire Gauge | 20 AWG |
| Wire Colors | White with Stripes, Gray with Stripes |
| Harness Length | 36 Inches |
| Connector | Sealed 8-Pin Female ECU Connector |
| Lead End | Unterminated Flying Leads |
Fitment
| EFI System | Compatibility |
|---|---|
| Holley Terminator X ECU | Compatible |
| Holley Terminator X Max ECU | Compatible |
| Connector Style | 8-Pin Sealed ECU Connector |
| Application | Universal EFI Installations |
Fitment Notes
- Designed specifically for Holley Terminator X and Terminator X Max ECUs.
- Provides access to all four programmable inputs and four programmable outputs available in the ECU.
- Some Terminator X kits include only a three-wire I/O harness; this harness expands the system to all eight available circuits.
- Unterminated flying leads allow custom wiring to switches, relays, sensors, and accessories.
- Verify ECU compatibility before ordering.
Tech Insight
1. What is this harness used for?
This harness provides complete access to the Terminator X or Terminator X Max ECU's four programmable inputs and four programmable outputs, allowing additional sensors, switches, relays, and electronic accessories to be integrated into the EFI system.
2. Why would I need this harness if my EFI kit already includes one?
Some Terminator X kits are supplied with only a three-wire I/O harness. The 558-462 harness populates all eight available terminals, allowing you to utilize every programmable input and output built into the ECU.
3. What can the programmable inputs and outputs control?
The ECU can be configured to monitor or control a wide variety of accessories depending on your calibration, including switches, warning lights, relays, electric fans, boost control devices, nitrous systems, and other programmable functions supported by the ECU.
4. Why are the leads left unterminated?
Flying leads allow builders to cut each wire to the exact length needed and terminate it with the connector best suited for the specific component being installed, resulting in a cleaner custom wiring job.
5. Is this harness weather resistant?
Yes. The ECU connection uses a sealed connector to help protect the electrical terminals from moisture, dirt, and vibration commonly encountered in automotive, racing, and off-road environments.
