Electronic tranny control compatability?

[Peter D. Hipson]

Jim, great writeup. I've also done some tranny work, and AFAIK, the
differences are physical between the T and the L versions. I don't think
that Dan will have any problems, except that there is a real possibility
that there will be a different connector to deal with <g>!

At 12:48 PM 7/22/2000 -0500, you wrote:
>    Dan,
>
>    Purusing
>
>    http://www.gmpowertrain.com/transmissions/4t65_main.htm
>
>which is for the 4T65E but which I believe's similar to the 4T60E, it's
>stated that:
>
>
>    - Shifts are controlled by two soleniods
>
>    - "Force motor control" to control line pressure for shift feel, aka
>    the "pressure control soleniod"
>
>    - PWM soleniod control for TCC control
>
>which, generally, is the same as the 4L60E, as I understand it.  However...
>
>    From my 1995 4L60E reference, "1995 S/T Truck Driveability, Emissions
>and Electrical Diagnosis Manual", November 1994, there's other ancillary I/O
>functions that may or may not be the same and may or may not need to be
>supported.  For instance, my 4L60E has
>
>    - Transmission range pressure switch assembly: A set of diaphragm
>switches that are actuated by pressures internal to the transmission which
>the ECU uses to sense the position of the manual valve (def'n below).
>
>    - 1-2 shift solenoid
>
>    - 2-3 shift solenoid
>
>    - 3-2 (downshift) control soleniod
>
>    - TCC clutch solenoid
>
>    - TCC PWM solenoid
>
>    - vehicle speed sensor aka transmission output shaft speed sensor
>
>    - transmission fluid temperature
>
>    - pressure control solenoid, i.e., for line pressure control
>
>    The manual on pg. 10A-14 also speaks of an ECU scan tool parameter
>called "TCC Slip Speed", which "is the difference between transmission input
>speed and engine speed".  This suggests that the transmission input speed is
>measured somehow as well, independently of the engine RPM, but I haven't
>determined if this is indeed the case and, if so, how it's implemented.
>Checking the Wiring Diagram for all ECU supported in this book shows no such
>sensor or wiring to the computer (pg. 10A-19 and 10B-18).
>
>    Note that there's no transmission fluid pressure sensor.  Thus, I assume
>that there's a built-in, known relationship between the PWM setting of the
>pressure control solenoid and the resulting line pressure.  Clearly this may
>be differently implemented in the two transmissions.  I'm aware the some
>ECUs have a transmission pressure map, and perhaps you could modify the
>existing ECU's map if necessary to accommodate any difference in the
>transmissions.  I can provide an example map for those who are interested.
>
>    The gear ratios of the two are very similar, so I believe that the
>existing shift selection calibration would work fine for the 4L60E.
>However, I've gotten a lot of satisfaction by modifying my ECU's shift
>tables so that the shifts are occur later than GM's design, and you may wish
>to do the same.
>
>
>    Jim
>
>--

Thanks, 
        Peter Hipson (founder, NEHOG)
        1995 White NA Hummer Wagon
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