Chrysler 41te Trans Control

[tjabo]

Yeah, should be just about enough time for me to realistically get it built. I've got to do a little bit of digging around for parts that are not on the BOM. I wish someone offered the case with the cleanly cutout endplate. . . i can get 'er done, but it won't be nearly as purty as one that comes in a kit!

[Bernard Fife]

might we be able to make some provisions for his to use them with this Mshift?

Thad,

Yes, if we can get the output curves for the pressure sensor(s) I will make it an option in the code. Also, the spare ADC report the ADC count directly to MegaTune, so the users can put their own curve in with simple modifications to the INI file (essentially you just enter an equation to convert the ADC count to pressure - I will post an example when it's appropriate). This is easy for most pressure sensors which have a linear output (unlike temperature sensors, which are more complicated).

Lance.

[tjabo]

Excellent, thanks Lance!

I'll be digging into the FSM this weekend, and I'll let you know as I learn about the trans. I'm sure Steve will continue to add pertinent information too.

We don't need to figure out how to adapt to his sensors for a month or so it appears, so that part can wait a bit (sounds like it might be one of the easier things we have ahead of us anyway).

Thad

EDIT: One other thing Lance, in my readings about the MShift/GPIO board, I haven't run across anything yet about the potential to run a boost control solenoid off of the GPIO board for a "boost by gear" effect. Has it been touched upon that you know of? Seems like duty cycles by gear would be sweet if there ends up being an available PWM output!

[Bernard Fife]

Thad,

Proper boost control is something that is being worked on in the background (I am not doing the work, though I have seen some of the ideas). Watch for an announcement on this in the not-to-distant fututre (presumably when the project is far enough along).

Lance.

[racerstev]

racerstev,

There is one dedicated line pressure input, and more free ADC (voltage measuring) inputs that could be used simultaneously for more pressure sensors, depending on things like the shift lever signal (for example, if the shift lever is voltage based rather than digital, there are two more ADC voltage channels available in the current code). There is also an ADC channel freed up if using CAN (w/ MS-II) to get the load (MAP or TPS).

The default line pressure sensor is for digikey MSP6907-ND for $114. It's a 0.5-4.5 Volt output (accuracy ±5 psi), and has just a three wire hookup (5V, ground, and signal). It has a 1/8" NPT thread.

The input shaft speed sensor is also used on the 4L80E transmission from GM, among others. We plan to support its use, but this isn't in the code at the moment. Once implemented it could be used for the 41te trans as well. The input shaft speed variable is in the code, but it is currently calculated from the output shaft speed and gear ratios (and assumes no slippage in the gears), it allows the code to derive the converter slippage. Of course measuring the input shaft speed directly is better for the reasons you mention, and this should be straightforward.

Lance.

Very nice! Of course more is better but we could get away with 2 inputs, just tune one shift then move the sensors to blend the next gear. The shift
lever signal is either a ground or a open on 4 seperate pins, I'll post from the shop manual tomorrow.

BTW Thanks for working with us on this trans, I really feel it's the future for our cars rather then the outdated 3 speed..

Steve

[Bernard Fife]

Thanks for working with us on this trans

racerstev,

Thanks to YOU and everyone who contributes. I have been working on this for a long time, and it's great to finally have other people involved!

Lance.

[racerstev]

I did a little digging,

Solenoid resistance is 1.4 ohm.

Range sensor. The manual calls the pins: T42-T41-T3-T1

------------------T42------------------T41---------------T3------------T1
Park--------------CL-------------------CL----------------CL------------OP
Reverse----------CL-------------------OP---------------OP------------OP
Neutral-----------CL-------------------CL---------------OP-------------CL
OD----------------OP-------------------OP---------------OP-------------CL
3rd----------------OP-------------------OP---------------CL------------OP
Low---------------CL--------------------OP--------------CL-------------CL

The factory shifters only use P R N OD 3 L, no 2nd gear. Now there IS a extra detent the factory dosn't use on the valvebody
so we can use that if you want to either mod the the factroy shifter for one extra detent or run a aftermarket shifter.

2nd CL OP CL CL
1st (low) OP OP CL CL

Just a note, the valvebody makes no changes at all in any forward gear, when you move the shifter all that gets changed is the
outputs on the range sensor. There are no hydralic changes at all..

The range sensor has a output for backup lights and your safety switch as well as a temp sensor. I can't seem to find the specs for the
temp sensor anywere...

We have 4 solenoids that need to to be operated. Two of these operate backwards, when you power them they turn off not on, this allows
the car to move in limp mode. So with no power at all to the trans you get 2nd gear...The solenoids are called:
Low/Reverse, 2/4, Underdrive and Overdrive.

------------------Low/reverse-----------2/4---------------Underdrive-----------Overdrive
1st gear-------------X--------------------------------------------X
2nd gear-----------------------------------X--------------------- X
3rd gear-----------------------------------------------------------X
4th gear (OD)-----------------------------X--------------------------------------------X

The 2/4 and Underdrive are the backwards solenoids.

Converter lockup is controlled by the Low/Reverse solenoid, once the trans shifts to 2nd gear a spool valve is moved that allows the lockup
to work with the L/R noid. So we have lockup in 2nd-3rd and 4th gear. On some VB's I block the spool valve in 2nd gear to allow a transbrake
to be used. Once this is blocked all that needs to be done to turn on the trans brake is to cut power to the 2/4 noid in 1st gear...

Steve

[Bernard Fife]

Steve,

1.4 Ohms is good to know - do you know if any/all of the solenoids are PWM'd to limit the current? (I suspect so, otherwise they would be drawing up to 10 Amps each, which seems excessive).

It looks to me like we can determine the shift lever position using just T42-T41-T3, T1 looks superfluous for the factory trans, but useful for aftermarket trans. shifters. This is a bit odd, because you only need 3 switches to specify 7 positions (PNR4321), but apparently Chrysler uses 4 switches. If I understand correctly, all gears except 1 can be spec'd without T1 - and it could have be assigned OP-CL-CL to avoid the need for an extra switch. I will look at the code to make 4 input for switches possible. Do these switches acts as grounds when closed? Does the voltage applied when they are open come from the ECU, or from the wiring harness?

I'm not sure if the solenoid chart shows an X for the state of the solenoids when powered, or when "on" (since two of these operate backwards, when you power them they turn off not). At first glance, it seems that the Low/Reverse, 2/4, Underdrive solenoids can be operated in the current code by the user-configurable Output1, Output2, and Output3. The Overdrive solenoid can be handled by the spare output 2 on VB2 (it is high current, and the user can configure it to come on in 4th/OD in the current code).

<edit> I see from reading your post again that X means "on", not "powered" since the trans goes to 2nd if all is unpowered. </edit>

Does anyone have info on how the line pressure is handled? And the TCC solenoid?

Thanks for the info Steve!

Lance.

[tjabo]

Hey guys!

I spent a couple of hours today with my nose in the FSMs, and predictably, Steve actually understands what's going on, where I'm just trying to figure it out. . .

What I thought I might be able to do that could be helpful is to post up some pics of certain pages of the FSM, but Steve obviously spent some time reproducing some of the same information in his diagrams.

One thing I was not sure about, and was hoping to figure out is whether it's actually necessary to even consider the switches, or whether they can be essentially forgotten and we could just think in terms of driving the solenoids directly. Apparently the trans control unit uses information from the range sensor and pressure sensors for feedback purposes that aren't necessarily relevant to us.

I can look for some information on the questions you posed at the end of your post Lance, but I have an idea that Steve might know this right off the top of his head!

Thad

[racerstev]

>>>>>>1.4 Ohms is good to know - do you know if any/all of the solenoids are PWM'd to limit the current? (I suspect so, otherwise they would be drawing up to 10 Amps each, which seems excessive<<<<

Yes they are all PWM'd, seems there range is from 55ish to 70ish, I've been told they can be pushed to 90% but I really havn't seen a reason to go past 65 or so. The factory gives them a 8ms "on"
shot before going to PWM.






>>>>>>Do these switches acts as grounds when closed? Does the voltage applied when they are open come from the ECU, or from the wiring harness?<<<<<<<<<

The switchs ground though the VB, the wires run directly to the TCM so I'm geussing power comes from there...



>>>>>This is a bit odd, because you only need 3 switches to specify 7 positions (PNR4321), but apparently Chrysler uses 4 switches.<<<<

We really don't even need an imput for P-R or N, all the work is done by the VB, just leave the power off to the noids untill it gets into
any forward gear.


>>>>>Does anyone have info on how the line pressure is handled? And the TCC solenoid?<<<<<

Line pressure is handled by a internal pressure valve, I set line pressure at around 165 for all gears except reverse. No electronic control here
at all.. The TCC is the L/R solenoid, once the trans shifts into 2nd gear the L/R controls TCC.

>>>>>One thing I was not sure about, and was hoping to figure out is whether it's actually necessary to even consider the switches, or whether they can be essentially forgotten and we could just think in terms of driving the solenoids directly. Apparently the trans control unit uses information from the range sensor and pressure sensors for feedback purposes that aren't necessarily relevant to us.<<<<<

Yes the factory pressure sensors, the looked great at 1st but really are kinda useless. These switch's just tell the TCU that there is pressure in the circuit, not how much pressure. They also lag so far
behind what's really going on they misslead you. Aftermarket pressure sensers tell the whole story..