If the ECU is the brain of your vehicle, then the harnesses are the nervous system. Everything that the engine sense, every action that it drives, is via one or more harnesses. Let's take a quick rundown of the different types of harnesses in a Holley EFI system:
- Main Harness:Connects the ECU to primary sensors and to the injector, ignition, and other sub-harnesses.
- Injector Harness: This sub-harness connects the injectors to the main harness.
- Ignition Harness: This sub-harness allows the main harness to receive timing and sends spark control to the coils.
- Auxiliary Harness: These are used to provide access to the user-defined inputs and outputs. Connects to I/O J-ports on ECU.
- Transmission Control Harness: Connects the electronic control unit of the transmission to the J4 port on the Dominator ECU (Only.)
- Drive-By-Wire Harness: Connects one or two drive-by-wire throttle bodies to the J3 port on the Dominator ECU (Only.)
- Other Harnesses:Other critical harnesses including the ECU power harness and harness extensions.
- Connectors: Allow you to create your own harnesses.