Toyota A750f Transmission control

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
Bernard Fife
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Joined: Fri Apr 04, 2008 1:28 pm

Re: Toyota A750f Transmission control

Post by Bernard Fife »

If I recall correctly (I haven't looked at the code for a while), the 40% limit is entirely in the INI. To change the limit, you need to find all the places in the INI it is specified and change it. This would be things like:

Code: Select all

  PCneutral        = scalar,  U08,   120,                      "%",    -1.00000,    -100.00,     40,    100,        0    ; pressure in neutral

Code: Select all

  pc_table         = array,   U08,   273,        [16x9],       "%",    -1.00000,    -100.00,     40,    100,        0    ; The PWM% for PC solenoid by load and mph 


You change the value of 40 to something lower like zero (which would be 100% PWM).

The lower limit of 40% prevents people from burning up their transmissions internally (both the friction elements from slippage and the solenoids from the higher current). But if you know what you are doing, you can probably go lower.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
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Joined: Wed Dec 28, 2016 11:59 pm

Re: Toyota A750f Transmission control

Post by vl-alexander »

Thanks. I'll try to change ini limits soon.

One more limit i noticed:
Spare port 0 PWM table - i put gear number on Y axis and speed on X axis to change spare PWM output duty depended on gear and speed. But i can not enter gear less than 0. So no able to make different duties for reverse and neutral.
Posts: 1
Joined: Thu Jan 11, 2018 10:25 am

Re: Toyota A750f Transmission control

Post by jarods7920 »

Hey, I am about ready to do this same thing.

Is the excel sheet you used exactly how you wired it or did you have to build and special circuits. I am going to be using this in my 4runner and hopefully with the 4runner shifter and it only has, PRND2L. Do you think this will be an issue?

I am a total newb to the megashift stuff, but been doing MS stuff for many years.

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