Ford Auto trans details

[Bernard Fife]

All,

At this weekend's meet in Calgary, it was noted that the Ford electronically controlled auto transmissions use a scheme to identify the shift lever position that used changing resistance (instead of a switch manifold and 3 digital inputs on the GM 4L60E).

Does anyone have reliable specs on what these resistances are in each gear so we can include this in the base code? It ought to be easy to do, and only uses one input (but an ADC pin).

Lance.

[devojet]

Ford Falcons in Australia use BTR gearboxes which also use the variable resistance for selector possition. I have the specs for that but I don't think the BTR gearbox is used much outside of Australia as it is very hard to find info on. It looks like all the specs I have show the voltage on the input pin to the ecu. So I guess there is a pull up resistor to 5v in the ecu. I guess I will have to do some measuring when I get a chance.

Anyway here are the specs I have found,

[p]3.8V-4.2V, [R]3.3V-3.7V, [N]2.8V-3.2V, [D]2.3V-2.7V, [3]1.8V-2.2V, [2]1.3V-1.7V, [1]0.8V-1.2V

Another thing with the BTR is it has two extra solenoids which are used in different paterns during sifting to control shift quality. Is it possible to add code to drive two outputs during a gear change then go back to normal after the change is complete? Does that make sense? If you PM me an email address I can send you a table that shows the solenoid possitions for each gear shift.

[Bernard Fife]

devojet,

What I am planning to do is let the user specify the resistances via MegaTune. That way most such schemes could be accommodated. But it's helpful to know the actual values, so we can set the circuits up properly for maximum resolution (and less fussiness for the user!). So thanks for what you posted - if we knew if they were 12V or 5V pull-ups that would help.

How many shift solenoids does the BTR have altogether? Adding outputs that activate only during a shift could be done fairly easily. However the current code only knows the state of the shift solenoids, it has no way of knowing when the actual shift is completed - does the BTR have a mechanism for this? (In the current code, the user inputs parameters - a constant plus a value based on the line pressure - to estimate the shift completion time.)

Lance.

[devojet]

The BTR has 7 solenoids altogether. 2 for shift pattern, 2 as mentioned above, 1 for Line pressure PWM, 1 for TCC lock up, and 1 I don't know about yet.
I'm not sure how the controller knows the shift has ended I'm guessing a timer is used, so I think what you said would be good enough. From what I have read if you don't operated the extra solenoids then the shift will just be a bit harsher.

Cheers

Daniel.

[Bernard Fife]

Daniel,

The code has two spare outputs already. I could add the option to set the state of these during a shift, but that would only work if the state was the same on each shift.

A better way would probably be to use a couple of unused pins (all the output circuits are currently used, so we would re-purpose a couple of VR circuits), and let the user specify the state of these for each of the 6 possible shifts (1-2, 2-3, 3-4, 4-3, 3-2, 2-1). Do we want control of these for PNR as well? I'm assuming these are on/off, but if we need PWM it can be done in software if necessary.

For the manual shift lever position sensing, we are already using all of the ADC channels, but since we won't need the 3 switch manifold channels anymore, we can put that on PAD00/GPI1 and all should be good.

Lance.

[devojet]

The state is different depending on which shift it is doing. they are just on/off valves and are not required for PNR.

regards

Daniel

[Bernard Fife]

Daniel,

Okay, great, I need to get the test units out, then I'll look at adding this to the code (both the resistance based manual gear lever position and the 2 extra outputs). The shift solenoids will be completely user settable (i.e., each one either on or off for each shift - I'll probably include PNR as well - on the chance that some other application might need it, but the user can ignore them if they are not needed).

For now I'll just do the code, but eventually it would be nice to know what sort of current these two extra solenoids require so we can spec the output circuits appropriately.

Lance.

[devojet]

Sounds Good. Can't wait for my test board to arrive.

I will have to measure the resistances of the solenoids.

Thanks

Daniel.

[DMX]

Hopefully this helps, (1995 Ford Taurus AX4S Transmission), alldata specs on Shift Lever indicator

Code: Select all

P - 4.41v - 4.16 KOhm
R - 3.60v - 1.44 KOhm
N - 2.83v - 733 Ohm
D - 2.09v - 401 Ohm
2 - 1.37v - 211 Ohm
1 - 0.68v - 81 Ohm

[Bernard Fife]

DMX,

Thanks, that's helpful! It would be interesting to know if the pull-up is in the ECU or in the transmission itself. I'll dig around and see if I can find out.

Lance.