This J4 auxiliary harness connects to the Dominator EFI J4 ECU connector, giving builders 26 user-programmable inputs and outputs. Note that the J4 connector is also used for transmission control applications, so confirm which auxiliary connector your build needs before ordering.
Specifications:
- Connector: J4
- Programmable I/O: 26 user-programmable inputs and outputs
- Harness Type: Auxiliary
- Part Number: 558-404
FAQ
What is the J4 connector used for?
It provides 26 user-programmable inputs and outputs on Dominator EFI, and is also used for transmission control applications.
How many programmable I/O does this harness provide?
26 user-programmable inputs and outputs.
Should I order this or the J3 harness (558-403)?
It depends on your build's I/O needs and whether you're using J4 for transmission control — check your Dominator EFI wiring diagram to confirm which connector your application requires.

