Holley's Dominator EFI Vehicle Management System is built for non-emissions street and race engines, with integrated transmission control, drive-by-wire throttle control, dual wideband oxygen sensor inputs, and enough onboard I/O to run boost, nitrous, and water/meth control without extra controllers. This kit bundles the main engine harness and EV1 injector harness for a GM LS 24x crank / 1x cam (LS1/LS2/LS6-style) engine, wired for 4L60E/4L80E transmission control.
Key Features:
- Individual cylinder fuel and spark control
- Self-tuning fuel table strategy that learns as you drive
- Integrated dual-channel wideband oxygen sensor control (NTK or Bosch sensors)
- 1-7 Bar MAP sensor capability for naturally aspirated or boosted applications
- Fully featured turbocharger boost control, eliminating the need for a separate boost controller
- 8-stage nitrous oxide control
- Integrated water/methanol injection control using Holley-calibrated solenoids
- Two-channel knock sensor inputs (1-wire or 2-wire sensors)
- Integrated electronic transmission control for GM 4L60E/4L80E
- Internal 4GB data logger with strip chart and smoothing tools
- Store up to four calibrations with the optional Multi Map Selector (558-407)
- Fully configurable laptop gauge panel
- Sealed automotive/marine-grade connectors and a fully potted ECU
- Compatible with optional 7" Digital Dash (553-106), 3.5" Touch Screen LCD (553-108), and 12.3" Pro Dash (553-111)
- Racepak Integration Module available
Specifications:
- Engine: GM LS1/LS2/LS6 (24x crank, 1x cam, EV1 injectors)
- Transmission Control: GM 4L60E/4L80E
- Drive-By-Wire Wiring: Not included in this harness (see 550-657)
- ECU Height: Variable, 1.00"-1.84"
- ECU Length: 13.14" overall
- ECU Width: 6.10" overall
- Mounting Bolt Pattern: 12.13" x 6.10"
- Kit Includes: Dominator ECU, USB cable, ECU power harness, engine main harness, EV1 injector harness, Bosch wideband sensor, ECU mounting hardware
- Product Type: Dominator ECU/ECM/VCM
- Part Number: 550-656
When using a transbrake, Holley requires installing either a relay or the Transbrake Input Protection Device (554-128) to protect the ECU from flyback voltage when the transbrake releases. Dominator EFI systems are sold a la carte — a complete install also requires the Main Power Harness, Wideband Oxygen Sensor, and Ignition Adapter Harness in addition to this kit. The ECU is certified to ISO 8846, SAE J1171, and USCG requirements for ignition protection and fire resistance.
FAQ
What engine does this harness kit fit?
It's built for GM LS engines with a 24x crank and 1x cam signal (LS1/LS2/LS6-style) running EV1-style fuel injectors.
Does this kit include the Dominator ECU?
Yes. It includes the Dominator ECU, USB cable, ECU power harness, engine main harness, EV1 injector harness, Bosch wideband oxygen sensor, and ECU mounting hardware.
Can this harness control my transmission?
Yes, this version is wired for integrated electronic control of GM 4L60E and 4L80E transmissions.
Does this support drive-by-wire throttle control?
Not in this configuration. For drive-by-wire throttle body support, use the 550-657 harness variant.
What else do I need for a complete Dominator EFI install?
Dominator EFI systems are sold a la carte. In addition to this harness kit you'll need the Main Power Harness, Wideband Oxygen Sensor, and Ignition Adapter Harness to complete the system.
Is a transbrake protection device required?
If you're running a transbrake, Holley requires a relay or the Transbrake Input Protection Device (554-128) to protect the ECU from flyback voltage when the transbrake is released.
