This harness expands Holley's transmission control options for 2009-and-newer GM 4L60 transmissions run with a Dominator ECU, adding an internal turbine speed sensor not found on earlier harness versions and controlling the valve body range selector differently from prior designs.
Specifications:
- For: 2009+ GM 4L60 transmissions, used with Dominator
- Feature: Internal turbine speed sensor (not on earlier models)
- Includes: Built-in relay (wire to switched 12V source)
- Requirement: Software version 5.0 build 100+ and ECU firmware 5.0 build 110+
- Compatibility Note: Not for 4WD installations
- Warning: California Proposition 65
- Part Number: 558-455
FAQ
What ECU does this transmission harness work with?
Dominator.
What software/firmware version do I need?
Software version 5.0 build 100 or higher, and ECU firmware 5.0 build 110 or higher.
Is this compatible with 4WD vehicles?
No, it's not compatible with 4WD installations.
What's different about this harness versus earlier 4L60 harnesses?
It includes an internal turbine speed sensor not present on previous models, and the valve body range selector is wired and controlled differently by the ECU.

