This extended-length Holley engine main harness fits LS1/LS6 engines from 1997-2004 and interfaces with 24x crank and 1x cam sensors, letting installers mount the ECU inside the passenger compartment, away from the elements and easy to access.
Specifications:
- Engine platform: GM Gen III LS1/LS6 (1997-2004)
- Crank/cam wheel type: 24x crank / 1x cam reluctor
- Compatible ECUs: Dominator, HP EFI, Terminator X, and Terminator X Max
- Length: 22" extended length for remote ECU mounting (roll bar, under passenger seat, etc.)
- Injector connector type: Not specified in available Holley data — this is the engine main harness, not the injector harness
- Throttle control (DBC/DBW): Not applicable/not specified — this harness does not include throttle body wiring
- Transmission control: Not included — this is an engine-only main harness (no transmission control wiring)
- Part Number: 558-133
FAQ
What ECUs is this harness compatible with?
Dominator, HP EFI, Terminator X, and Terminator X Max ECUs.
What crank/cam signal does it use?
24x crank and 1x cam sensors, for LS1/LS6 engines built 1997-2004.
Can I mount the ECU somewhere other than the engine bay?
Yes — the 22" extended length lets you mount the ECU in the passenger compartment, on a roll bar, or under the passenger seat.
Does this harness include transmission control?
No — this is an engine-only main harness; transmission control wiring is not included.

