Holley Terminator X Max pinout and specs

Checked against the maker's documents 27 September 2026

Holley Terminator X Max is a 89-pin wire-in Holley ECU on 4 connectors: J1A (34 pins), J1B (26 pins), J3 (13 pins) and J4 (16 pins).

It has 8 injector outputs and 8 ignition outputs. The injector drivers are saturated, which means high-impedance injectors. Low-impedance ones need a ballast resistor pack or a different ECU. The ignition outputs are logic-level. Smart coils plug straight in; dumb coils need an igniter in between.

There are 2 dedicated trigger inputs, each happy with a VR or a Hall sensor. Two knock inputs cover both banks of a V engine. It has an onboard wideband controller, so a sensor wires straight in. The MAP sensor is built in.

Drive-by-wire is native: 1 throttle from its own H-bridge outputs. One CAN bus handles dashes, PDMs and expansion. Three outputs can switch 12V as well as ground.

Spec sheet

Which builds it suits

Of the 58 swap presets in the planner, 4 fit as they are and 53 fit with add-ons; 1 does not fit at all. The add-on it asks for most often is the Holley Pro Dash (with I/O). Where it falls short, it is usually not enough knock inputs. The planner fills anything a preset leaves open with its ordinary defaults, so your own build may land differently.

It runs the Honda K20 (i-VTEC 2.0 NA), Honda K24 (i-VTEC 2.4 NA), Mazda Rotary 13B-MSP Renesis (RX-8 manual, 6-injector) and Mazda Rotary 13B-MSP Renesis (RX-8 auto, 4-injector) presets with nothing added. The GM LSA (Gen4 6.2 alum, S/C) needs a CAN wideband module. The Nissan VQ35HR (High-Rev, 2007+) needs Holley Pro Dash (with I/O) and a CAN wideband module. It can't run the BMW S54 (3.2 NA I6, E46 M3): not enough knock inputs.

Plan a build around the Holley Terminator X Max

Pin table

By connector: J1A carries 2 trigger inputs, 2 knock inputs and 10 analog inputs; J1B carries 8 injector outputs, 8 ignition outputs and 4 H-bridge outputs; J3 carries 4 analog inputs and 2 H-bridge outputs.

Other Holley ECUs

The closest Holley unit is the Holley Terminator X. Against it, this one has 89 pins (the Terminator X has 60) and 1 drive-by-wire channel (the Terminator X has none).

• Holley Terminator X
• Holley HP EFI
• Holley Dominator

Source: Holley documentation for the Terminator X Max

Always verify against the manufacturer's manual and your tuner before wiring.