Holley EFI Main Power Harness for Avenger, HP & Dominator EFI – 13 ft.
558-308
The Holley EFI Main Power Harness for Avenger, HP & Dominator EFI – 13 ft. provides the primary battery power connection required for Holley EFI engine management systems. This heavy-duty 10 AWG harness is required for HP EFI and Dominator EFI ECUs and is also compatible with Avenger EFI systems. Its 13-foot length offers flexible routing while maintaining reliable power delivery directly from the battery.
The harness is protected by a 40-amp fuse and enclosed in braided split loom to resist abrasion in demanding automotive and off-road environments. Two 3/8-inch battery ring terminals and heat shrink tubing are included for a clean, secure installation. For maximum ECU performance and reliability, Holley specifies that this harness must be connected directly to the battery terminals.
Includes:
- (1) Holley EFI Main Power Harness
- (2) 3/8" Battery Ring Terminals
- Heat Shrink Tubing
- 40-Amp Fuse Protection
- Braided Split Loom Covering
Specifications
| Specification | Details |
|---|---|
| Manufacturer | Holley EFI |
| Part Number | 558-308 |
| Product Type | Main Battery Power Harness |
| Harness Application | Universal |
| Harness Type | Main Battery Power |
| Compatible EFI Systems | Avenger EFI, HP EFI, Dominator EFI |
| Wire Size | 10 AWG Automotive TXL |
| Harness Length | 13 Feet |
| Fuse Rating | 40 Amp Maximum |
| Protection | Braided Split Loom |
| Category | Ignition |
Fitment
| EFI System | Compatibility |
|---|---|
| Holley Avenger EFI | Compatible |
| Holley HP EFI | Required |
| Holley Dominator EFI | Required |
| Application | Universal |
Fitment Notes
- Required for Holley HP EFI and Dominator EFI ECU installations.
- Compatible with Holley Avenger EFI systems.
- The harness must be connected directly to the battery terminals.
- Do not connect the harness to a battery disconnect switch, starter solenoid, power distribution stud, or other intermediate power source.
- If additional length is required, Holley recommends extending the harness using 8 AWG or larger multi-strand wire.
FAQ
1. Why must this harness connect directly to the battery?
Holley specifies a direct battery connection to ensure the ECU receives clean, stable voltage without interference or voltage drop caused by disconnect switches, starter solenoids, or power distribution blocks.
2. Why is 10 AWG wire used?
The heavy-duty 10 AWG Automotive TXL wire is designed to safely carry the current required by Holley EFI systems while minimizing voltage loss over the harness's 13-foot length.
3. Can this harness be extended?
Yes. If additional length is required, Holley recommends extending the wiring using 8 AWG or larger multi-strand wire to maintain proper current capacity and minimize voltage drop.
4. What is the purpose of the braided split loom?
The braided split loom protects the wiring from abrasion, vibration, and heat commonly encountered in automotive, racing, and off-road environments while allowing easy routing through the engine compartment.
5. Is this harness fused?
Yes. The harness includes integrated 40-amp fuse protection to help safeguard the EFI power circuit against electrical faults while providing reliable battery power to the engine management system.
