How Holley Outputs Work
I figured this out back in 2018 when some customers were confused by what Holley output drivers were doing. These drivers are the same for Terminator-X, HP, and the Dominator. Obviously, only the Dominator has more outputs, but the pin numbers are the same.
Output Driver Types:
In the software, when you pin to an output, you simply pick an output type for the active state:
H for High-side. Outputs a +V, or a ground, when activated
G for Low-side. Outputs a ground when activated
P- for PWM negative pulse width modulated
P+ for PWM positive pulse width modulated
The two types of H for high-side drivers are called “Half-Bridge” and the “Intelligent HS.” The H is a misnomer because Half-Bridge drivers drive the output both ways. They forcibly drive the output pin to either the internal +V (H) or Ground (G). The “H” implies that these outputs are for driving positive voltage outputs, and that’s true, but they also drive the outputs to zero as well.
Overcurrent (~10A) in the Half-Bridge output shuts down the driver until you cycle the power. The Intelligent driver is also a Half-Bridge, but it doesn’t shut down; it cuts back to a lower current. Think of both of these drivers as two FET transistors. One pulls the output HIGH, up to the internal positive source, and the other pulls the output LOW down to ground. 2A is considered the max current.
The other type G is called a Low-Side driver, called Open Collector LS.
In the Open-Collector driver, when the output deactivates, the output pin is “let go” so the output positive voltage is determined by an external source such as a pull-up resistor. Often the external load provides this; if not, you have to add a resistor, usually in the 400 ohm range. The benefit of the Open Collector style of driver is that the positive output voltage is determined outside the ECU. It’s a simple switch to ground when it’s trying to output a low. The two special “intelligent LS drive” outputs (3 and 4) have a slightly lower voltage drop when active and are the ones normally used for PWM requirements for that reason.
What happens at power up:
Outputs can transition through an indeterminate state during power-up of the ECU. This usually lasts only milliseconds, if it happens at all, but it can result in very short inadvertent activation of devices on power-up. Also, some outputs can transition through indeterminate states upon power down or when the main power is disconnected from the ECU. Because of this, if you have critical outputs, it’s a good idea to isolate those outputs. For example, if you're using a nitrous driver that receives power even when the ECU doesn’t, it would be a good idea to have your nitrous enable switch disconnect that output. That way, nitrous activation would not happen during these transitional periods since the nitrous enable switch should not be activated.
Here are the pins for all outputs on all four connectors:
J1 and J2 are available in all Holley ECUs.
J3 and J4 are additional in the Terminator-X-Max and the Dominator.
Connector Jack * Pin Number * Output Number * Type (H, G or P- or P+) * Driver Type
J1 B12 Output 01 H, P+ Half‐Bridge
J1 B11 Output 02 H, P+ Half‐Bridge
J1 B10 Output 03 G, P‐ Intelligent LS
J1 B03 Output 04 G, P‐ Intelligent LS
J2 B12 Output 05 G, P‐ Open Collector LS
J2 B06 Output 06 G, P‐ Open Collector LS
J2 B08 Output 07 G, P‐ Open Collector LS
J2 B21 Output 08 G, P‐ Open Collector LS
J2 B05 Output 09 G, P‐ Open Collector LS
J2 B11 Output 10 G, P‐ Open Collector LS
J2 B03 Output 11 G, P‐ Open Collector LS
J2 B09 Output 12 G, P‐ Open Collector LS
J2 B24 Output 13 H, P+ Intelligent HS
J2 B25 Output 14 H, P+ Intelligent HS
J2 B02 Output 15 H, P+ Intelligent HS
J2 B01 Output 16 H, P+ Intelligent HS
J2 B04 Output 17 H, P+ Intelligent HS
J2 B10 Output 18 H, P+ Intelligent HS
J2 B22 Output 19 H, P+ Intelligent HS
J2 B23 Output 20 H, P+ Intelligent HS
J3 B13 Output 21 G, P‐ Open Collector LS
J3 B12 Output 22 G, P‐ Open Collector LS
J3 B11 Output 23 H, P+ Half‐Bridge
J3 B10 Output 24 H, P+ Half‐Bridge
J3 B19 Output 25 H, P+ Half‐Bridge
J3 B26 Output 26 H, P+ Half‐Bridge
J4 B13 Output 27 G, P‐ Open Collector LS
J4 B07 Output 28 G, P‐ Open Collector LS
J4 B02 Output 29 G, P‐ Open Collector LS
J4 B01 Output 30 G, P‐ Open Collector LS
J4 B11 Output 31 H, P+ Half‐Bridge
J4 B05 Output 32 H, P+ Half‐Bridge
J4 B12 Output 33 H, P+ Half‐Bridge
J4 B06 Output 34 H, P+ Half‐Bridge
J4 B04 Output 35 H, P+ Half‐Bridge
J4 B03 Output 36 H, P+ Half‐Bridge
Holley EFI Technical Information
On this page we will post documents, notes and videos pertaining to the Holley EFI systems.
Obviously you will probably have questions, so don’t hesitate to call us at 209-247-6497
A surprise article showed up on the Hot Rod Magazine web site:
There is a lot going on with Holley EFI systems and software
Some of the links below are a download of a WORD document.
We did this so you would automatically have a document that you could print.
V6 Build 400 update for HP & Dominator ECUs
and Terminator-X V3
Datalog setup now show colors
Tune using Lambda if you want
Axes are much easier to see
ADDITIONAL V6B400 IMPROVEMENTS (Click here for a video)
• Color options for datalog screens
• Manually test outputs one at a time - Click here
• Easier to see and adjust table scales.
• Email Global File/Save to Desktop Options
• Additional Water meth control options
• Support for Holley Can I/0 module
• New supported injector options
• Automatically check for update option
• New drag race transmission control (dump valves, lockup control, etc.)
• New Nitrous control additions
• Support for Terminator X Stealth throttle body with Dominator ECU
Here is an Excel Spreadsheet
that compares the terminator-X line to the other Holley products
What? No Installation Instructions or Documentation?
All documentation is included within the software. Install the appropriate software and go to Help. All the information is there starting with the installation.
Helpful conversion:
I don't know how many times people have asked "what the hell is a kilopascal" in terms that they are used to thinking about.
Here's an easy way to interpret that axis. Since vertical axis is manifold vacuum and/or pressure (MAP), go to Toolbox/Preferences and click on Display MAP as PSI. Negative PSI is vacuum, positive PSI is ... PSI ... duh. To convert from a negative PSI to inches of vacuum just double the number. So -5 PSI on the scale is 10 inches of vacuum. Simple, right? If you are using a 1-Bar Map sensor the vacuum will go from 0 at the top to some level of maximum vacuum at the bottom such as -12. That is the same as no vacuum to 24" of vacuum.
Injector Types:
There are many different styles and types of fuel injectors but here's a picture of the basic normal vs stubby types. Note also that there are different connectors with the most common being EV1 and EV6. Also here is the injector offtime information for Holley injectors.
IAC Wiring Considerations
Here's a drawing of the IAC wiring options. Customers buying the Holley EFI systems do not realize that Holley likes to use Chrysler IACs because they flow more air than a standard GM LS style. If you are configuring a system that uses a "standard" GM IAC you will have to make a minor wiring change in order for the IAC to work.
To find out which type of IAC you have, look at the drawing below.
With an ohm meter measure between the center two pins (B and C) of your IAC.
If it’s an open – you have a GM style IAC.
If you see resistance you have a Chrysler style IAC
