Custom 4T40E Trans Controller - Page 4 - Tuning Forum

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Re: Custom 4T40E Trans Controller
Friday, February 25, 2011 2:54 PM
Bachelor's degree in Electrical Engineering from the University of Illinois @ Urbana/Champaign.....but honestly, embedded programming has little to do with my education.




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Re: Custom 4T40E Trans Controller
Wednesday, March 02, 2011 2:52 PM
Programming is fun.

Thats all I have to add to this.



Re: Custom 4T40E Trans Controller
Thursday, March 03, 2011 3:39 AM
Any updates?





Re: Custom 4T40E Trans Controller
Thursday, March 17, 2011 7:58 PM
-MD- Enforcer wrote:

Any updates?

x2


LOL
Re: Custom 4T40E Trans Controller
Friday, March 18, 2011 1:12 PM
I know I keep blue balling everyone here, but certain complications have kept me from testing it. However, those complications have now past. I intend to start testing this weekend.




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Re: Custom 4T40E Trans Controller
Friday, March 18, 2011 3:17 PM
Whalesac wrote:

I know I keep blue balling everyone here, but certain complications have kept me from testing it. However, those complications have now past. I intend to start testing this weekend.
YAHH!! Good luck bro


LOL
Re: Custom 4T40E Trans Controller
Monday, March 21, 2011 3:57 AM


A few complications...





Re: Custom 4T40E Trans Controller
Wednesday, March 23, 2011 6:22 PM
well....I think it doesn't work.

I never actually tried to control the transmission, but I found something interesting. I powered the board with the stock pcm controlling the trans and when I move the position lever, the jbody gauge cluster initially displays P, R, N and D correctly but when I get to "3" the cluster basically freezes on 3. In other-words, "2" and "1" are never displayed. Also, when I try to go back, P R N and D normally don't get displayed. I say "normally", because one time it basically had a seizure, quickly switching between "R" and "3" when I had it in reverse. It makes sense that if any position were to be screwy, it would be "3" since it's the only position where all 4 transmission position switches are either ground or high. So, I don't foresee this being difficult to debug. I have some ideas as far as what to check. When it warms up, I'll hook up my oscilloscope.

In any case, just visually, the leds on the trans board display what I expect:. Unfortunately though, I put checks in the code to keep from switching shift solenoids under and/or over a given vehicle speed, which prevents shifting in trans positions "1", "2" and "3". I'll take these checks out and see if I can manually shift and straight shift according to "1", "2" or "3" lever positions. I also need to check TPS vs duty cycle, as well as RPM vs duty cycle for the EPC and TCC solenoids before I have enough confidence in letting my board control the trans.

Sorry I don't have a better update guys. I'm hoping the next update can be a little more exciting (maybe with another video )




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Re: Custom 4T40E Trans Controller
Thursday, March 24, 2011 3:38 AM
Well you know how not to do it. lol





Re: Custom 4T40E Trans Controller
Tuesday, March 29, 2011 8:00 PM
A little video to show you guys what I'm talking about. NOTE: in the video, I have come to the realization that Trans Switch A (not D or P) was the one lead that wasn't cut.



These are the "ABCD" (or "ABCP") trans switch combinations that the PCM should see for each lever position...

Selection.............ABCD
P...........................0110
R..........................1010
N..........................0011
D..........................1001
3...........................0000
2...........................1100
1...........................0101

What we see in the video, intuitively makes sense. If Trans Switch "A" is the only signal being loaded, then what the JBody PCM sees is...

Selection.............ABCD
P...........................0110
R..........................0010 <-- Invalid combo
N..........................0011
D..........................0001 <-- Invalid combo
3...........................0000
2...........................0100 <-- Invalid combo
1...........................0101

... and therefore R,D and 2 are never displayed on the gauge cluster.


Well, anyways... like I said, I'll try some resistors to increase input impedance to the PIC. If that doesn't work, then I'll have to build some buffers. Oh well...




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Re: Custom 4T40E Trans Controller
Tuesday, March 29, 2011 8:17 PM
I am now more confused...

Now that I looked more at the code and PCB, it was in fact Trans Switch "D" that wasn't cut. I think I have my ABCD logic backwards (i.e. replace "ABCD" with "DCBA"). I'll have to look into this more, but I'm too tired to do it tonight.




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Re: Custom 4T40E Trans Controller
Wednesday, March 30, 2011 7:18 AM
Owell at least you've made some progress. The bugs your working out don't seem to be to serious. Keep up the good work. -DR


LOL
Re: Custom 4T40E Trans Controller
Thursday, April 14, 2011 7:56 AM
How it going Whalesac any more progress?


LOL
Re: Custom 4T40E Trans Controller
Thursday, April 14, 2011 8:02 AM
Yeah, updates?




Re: Custom 4T40E Trans Controller
Thursday, April 14, 2011 8:09 AM
yea brian what the hell man!



Re: Custom 4T40E Trans Controller
Sunday, April 17, 2011 8:50 AM
No real updates. The resistor idea didn't work, so I'm going to have to build some buffers instead. I want to hook my scope up to the ABCD signal wires before I even do that, so that I know what the open circuit voltage is and to test how much current draw I can afford before it starts loading down the line.

I have also been teaching myself C# for work, and it just so happens that it would be perfect for the trans controller interface for the user. I built this real quick yesterday...






and for anyone interested in how the B&M ShiftPlus works...Click







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Re: Custom 4T40E Trans Controller
Sunday, April 17, 2011 9:35 AM
I'll donate a auto trans intercepted if it would help.



Re: Custom 4T40E Trans Controller
Monday, April 18, 2011 10:13 PM
I appreciate the offer Mike, but I'm pretty sure the Interceptor doesn't interface with the range switch, and besides, I prefer to come to my own conclusions through R&D rather than blindly copying another product. Thanks anyways.

I worked on the program a little more today.





I will be changing the framework a little more, but the window on the left side is what you get when the program opens. The right window pops up when you select a Transmission and click "Edit Transmission". (or if you select "ADD TRANS" from the dropdown box) It's better this way, because these parameters don't change once they are all set correctly...leaving the tuning window more compact and less distracting. I will be adding tuning parameters for the "Auto Shifting" routine, as well as the Trans temp and CLT sensor TCC lock thresholds.


If anyone has any features they would like to see implemented, let me know, and I'll see what I can do.




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Re: Custom 4T40E Trans Controller
Tuesday, April 19, 2011 10:50 AM
Interesting, are you going to allow any adjustment of the shift pressure via a pot or some kind of resistor magic?




Re: Custom 4T40E Trans Controller
Tuesday, April 19, 2011 12:05 PM
-MD- Enforcer wrote:

Interesting, are you going to allow any adjustment of the shift pressure via a pot or some kind of resistor magic?

That's what the EPC PWM is for. The lower you set the duty cycle (all the way down to 0% ), the greater the line pressure will be. If you look at the table, you see that I have the duty cycle decreasing with increasing engine load.

I have thought about adding in a feature that reads the EPC and TCC pulsewidths from the stock PCM along with an external pot, so that people can run it as a piggyback like the Interceptor or Shift Plus...but I can't fathom why anyone would want that when they can have full control.




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Re: Custom 4T40E Trans Controller
Tuesday, April 19, 2011 12:31 PM
Agreed, I could not tell that from your pic.





Re: Custom 4T40E Trans Controller
Saturday, April 23, 2011 10:59 AM





I took some voltage measurements today...

Selection.......A.....................B.....................C......................D
P.....................0..................12.4...............12.4.....................0
R.....................0.....................0..................12.4..................12.2
N..................12.4..................0...................12.4....................0
D..................12.4..................0......................0....................11.8
3......................0.....................0......................0.......................0
2......................0...................12.4..................0.....................11.8
1...................12.4................12.4...................0........................0


or logically,


Selection.............ABCD
P..........................0110
R..........................0011
N..........................1010
D..........................1001
3...........................0000
2...........................0101
1...........................1100


...which means,, wherever I got that info earlier on the position switches wasn't correct for the 4t40e (or at least not for the Cavalier). This is also good news. Considering these are 12V referenced switches, that means I don't need a complex buffer to bring the signal to a 5V reference. For now, I'll just do a voltage divider. In the future, It'll probably be the output of the voltage divider gating a mosfet on the 5V line of my Trans board.

Well, I'm about to fire up the soldering iron. I'll update tonight if it works (hopefully I haven't fried both PICs with that 12V signal)..




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Re: Custom 4T40E Trans Controller
Saturday, April 23, 2011 11:05 AM
Me like.

Looks like it could control a lot of transmissions with options for 9 gears and 3 solenoids.


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs
Re: Custom 4T40E Trans Controller
Tuesday, April 26, 2011 5:08 PM
Interesting. Keep up the good work.



Re: Custom 4T40E Trans Controller
Wednesday, April 27, 2011 3:50 AM
Well what happened!





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