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MegaShift™ Transmission Controller

The MegaShift™ automatic transmission controller code is full-featured code (see features below) designed for the GPIO board from Bowling and Grippo. MegaShift™ (aka. "MShift™") is designed as a 'universal' flexible DIY automatic transmission controller, adaptable to many electronically controlled transmissions.

MegaShift™ with the GPIO board has been in use since early 2006 in testing in a variety of vehicles, and has been in production since the Fall of 2009. The GPIO board was designed with transmission control in mind - it is not a 'hacked' engine controller with inherent compromises and limitations. It also costs significantly less than a MicroSquirt® controller or a complete MS-II® controller.

You can buy the GPIO board right now from DIYAutoTune (the MShift™ code is free to download).

Applications include the 4L60E and 4L80E 4-speed overdrive transmissions from General Motors (the defaults are for the 4L60E), Chrysler 41te, as well as many other similar electronically controlled automatic transmissions.

Here is a brief, grainy flash video of MShift™ and TunerStudioMS in action on the test bench: MShift_demo.flv (2.5MBytes)

MegaShift™ on the GPIO board has the following features:

The MegaShift™ controller code (for the GPIO hardware) uses the CAN (controller area network) to communicate with MegaSquirt-II™ controllers to get get the current load, battery voltage and engine rpm (and other variables you might want to add to the code). It also allows you to use a laptop connected to the MS-II™ to configure, monitor, and datalog the MShift™ controller. However, the CAN communications can be disabled for stand-alone use of MShift™ on a GPIO board with the load determined from a throttle position sensor (TPS), Manifold Absolute Pressure (MAP) sensor or Manifold Air Flow (MAF) sensor (though the user loses the over/under rev protection and the battery voltage PWM adjustments).

When CAN is used, this load channel is available to view and log any 0-5 Volt signal (or higher, with an appropriate voltage divider circuit made up of two resistors and a Zener diode) in TunerStudioMS. The line pressure channel is also available for datalogging if not used for the recommended line pressure sensor.

The code starts in one of the two user-selectable auto-modes (sequential shift or skip-shift). Manual mode can be selected at any time by pressing either shift button. Once in manual mode, auto-mode can be re-engaged by:

In Auto mode:

In Manual mode:

In either mode:

Note that the GPIO with the MegaShift™ code only controls the forward gears. You will still require a mechanical shifter to place the transmission into Park, Reverse, or Neutral. The manual shift lever also indicates the maximum gear the controller ought to select - for example, if the shift lever is in second, the transmission controller will limit the transmission to first and second gear only.

The transmission's fluid temperature is sensed by the transmissions internal temperature sensor (the default is 4L60E's GM sensor, but other sensors can be used). A timer channel is used to get the vehicle speed from the VSS sensor on the output shaft, and the TunerStudioMS interface has both a speedometer and an odometer (configurable in miles or kilometers).

For a complete listing of the set-up and tuning parameters for your MegaShift™/GPIO controller, see: Editing MegaShift™ Parameters

GPIO boards from Bowling and Grippo are now available from DIYAutoTune, as well as other MegaSquirt® vendors.

© 2004, 2015 Bruce Bowling and Al Grippo. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.