Holley Introduces the Terminator X Engine Controller for G3 Hemi

As more and more Mopar enthusiasts opt to swap a late-model Hemi into their early Detroit iron, the complexities of the electronics of these new engines can lead to frustration. There are requirements to modify the OEM wiring harness, and there are constant struggles to get the PCM to work with the harness in the early Mopars. Holley has recently introduced the Terminator X (and Terminator X Max) controller for the 2003-2013+ G3 Hemi, which greatly reduces the difficulties of using the Hemi’s electronic components.

The Terminator X provides a plug-and-play engine controller solution along with options for boost and nitrous controls. Additionally, the Terminator X is compatible with Holley EFI accessories, which include analog gauges, shift lights, modules/controllers, and their Pro Dash systems. Depending on your engine (non-VVT 5.7L, 6.1L or 6.4L) and fuel injector harness configuration (EV1 – Jectronic/Minitmer (Bosch) or EV6 – USCAR), there are four different options (part nos. 550-1222, 550-1223, 550-1224, or 550-1225) offered by Holley to cover your Hemi’s combination. The Terminator X high impedance fuel injector drivers will operate factory stock injectors or aftermarket Holley injectors.

Above left: The Terminator X GEN III Hemi kit includes an electronic control unit (ECU), a touchscreen handheld, a pair of Bosch LSU 4.9 wideband Oxygen sensors (Lambda sensors), a built in 1-bar manifold absolute pressure sensor (MAP), and all the harnesses necessary to control the Hemi’s electronics. Above right: The Terminator X has eight built-in LEDs in the ECU. The flashing of these LEDs will provide vital information about the Hemi and will display any potential problems that occur with the operation of the components on the Hemi.

Included with all the G3 Hemi Terminator X kits are Bosch LSU 4.9 wideband Oxygen sensors (Lambda sensors), a built in 1-bar manifold absolute pressure sensor (MAP), an electronic control unit (ECU), a touchscreen handheld, vacuum hose adapters, and all the required harnesses. The internal MAP can be disabled if boost applications are utilized. With the presence of boost, a terminated connector allows a seamless installation to utilize an external MAP sensor harness.

The compact size of the ECU allows it to be mounted in nearly any location in the automobile. The ECU should be mounted face up so the eight built-in on-board diagnostic LEDs can be monitored for system operation and any latent software/hardware concerns. A 3.5-inch touchscreen handheld allows the operator the ability to build base tunes, data log, and develop custom gauge displays.

Above left: The Terminator X ECU requires only four harness connectors to operate. There is a harness for the power to the controller. There are two connectors that allow communication between the computer and the sensors and actuators. Connector J1A is designed primarily as the input connector, and connector J1B is the output connector. Finally, there is an internal MAP sensor connector. Above right: There is a great deal of user input control. This is accomplished using the 3.5-inch touchscreen handheld. The Terminator X controller includes free software full of base tables and maps necessary to operate the Hemi.

Lastly, if you desire some type of power adder, the Terminator X has integrated boost control with the handheld, which allows simple engine timing or air-fuel ratio (AFR) changes. If you are a more advanced tuner, the Terminator X has well-designed boost control software that enables the user to determine the boost by time, gear, RPM, or speed, and all the adjustments work with the software’s pre-programmed safety controls. With the use of nitrous, the handheld provides options to adjust the minimum/maximum RPM for the nitrous activation, set the target AFR, control the engine ignition timing, and develop custom curves for ignition timing and the nitrous percentage.

With the introduction of Holley’s Terminator X, you now have an additional option when it comes to how the Hemi will be electronically controlled. The Terminator X will operate factory components or will equally control aftermarket parts, and the Terminator X provides a plug-and-play engine control with optional user input. If you are in the middle of a swap or are considering one in the future, check out Holley’s website for a list of the full benefits of the Holley Terminator X.

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Chris Holley

Chris Holley

Technical Contributor Chris has been a college professor for 20 years; the last 15 spent at Pennsylvania College of Technology in Williamsport, PA. During the day Chris instructs HVAC and electrical/electronic classes, and high-performance classes, which includes the usage of a chassis dyno, flow benches, and various machining equipment at night. Chris owns a '75 Dart, a '06 Charger, a '12 Cummins turbo diesel Ram, and he is a multi-time track champion (drag racing) with his '69 340 Dart, which he has owned almost 30 years.


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    • Kevin Shaw
      Kevin Shaw 8 January, 2020 at 08:42 Reply

      You’ve got quite a few options! Obviously, a manual transmission is the low-hanging fruit. Besides a A-833 4-speed, American Powertrain has a ready-to-bolt in 5-speed Tremec kit, as well as a big-daddy 6-speed Magnum. Equally, Silver Sport Transmissions (SST) has a modified 5-speed Tremec and 6-speed Magnum that both place the shifter in the factory location if you want to run a factory-style center console. Equally, SST has its 4-speed A41 overdrive automatic, which uses a modified 4L60E case with a Chrysler tail cone and bellhousing. The A41 uses its own stand-alone harness with a TCI transmission controller (TCM). Speaking of TCI, they offer a 6-speed overdrive automatic with a Chrysler bellhousing, it’s own harness and TCM computer too. As far as “harness-less” automatics & overdrives, you’ve got 3-speed 904s, 727s, and 4-speed A518s. The most effortless overdrive would be a 727 with a Gear Vendor overdrive, as all that’s required is a little notching on the cross member and shortening your driveshaft. There’s a little bit of wiring to do, but nothing like an automatic requiring a TCM.

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    Joseph Butterfield 17 March, 2020 at 14:52 Reply

    I’m looking to install an 06 6.1 hemi crate engine in to my 79 plymouth trailduster 4×4 does the terminator x max control transmissions, 545rfe , and does it do a relearn procedure, as this transmission will be fully rebuilt

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