stand alond tcu

I'm going the option of the mega shift with my megasquirt3 system.

 

i have done some figuring and found the wires and functions for all the solonoids going into the tranny.

5 EAT WIRE INDIFICATION.pdf

this is the logic of whitch the solonoids are controld

so cut the 11 wires that we need. solder in a db 25 or 37 connector ( printer or computer screen plugs about 2$ each )

 

and these wires will go to the megashift or what ever control module.

 

 

to make the check engine light go off the only thing that i can think of is to do like some one changing to a 5mt or 6 mt car switch ecm and dash to manual version.

 

other than that the steering wheel pushbuttons will go to the controler and the few position switches of the shifter will also go the controler.

gonna cut my first wire in about 45 seconds !

So how goes it?

So cut the green white wire on pin 23 of the grey connector it's for the transfer clutches.

 

As expected the diff is then fully open.

 

With that wire cut the sport mode started flashing.

I have p0700 disabled in the rom so the tranny cannot make the check engin light come on.

 

I figured in advance the tcu will want to see some resistance at least in that cuirit.

 

I spliced in a wire so I can have a remote switch.

 

Surprisingly when I connected the wires again and measured the voltage it's a 2-5 volt system I thought it would go to 12v

 

I get around 2-2.2v at idle and cruise

And up to 4.8 v at wot while holding the brakes

 

And there is no difference when in manual mode or auto for the voltage.

I jacked up the rear wheels

Keep in mind I have the center diff removed so the car is now rwd with the power from the transfer clutches the only way to send power to the front wheels.

 

With the are connected the car pulls ahead easily via the front wheels.

Wire disconnected the rears spin freely with no power what so ever to the front .

 

Connect the wire when rear tires are spinning and instant lurch ahead. So the clutches apply real quick!

 

Tomorow I will give the wire switched 5 volts and see what the performance is.

 

So it will be

 

Wire disconnected and signal from tcu connected to ground via resistor I don't know the minimum size to prevent the tcu from setting a code.

 

Off fully open rwd

 

Auto front power engaged from tcu logic

 

 

On direct 5 v to the solonoid providing maximum power to front wheels at all times

Nice!

so we need a 2-4 ohm resistor. it see up to 1 amp at 5 volts so that = 5 watts

 

so would need at least a resister at least 5 watts in heat dissipating ability. i'm actually using a 300 foot spool of wire we had in stock for this test. its about 1.7 ohms.

 

this is whats needed to fool the tcu into thinking its connected to the awd solonoid. i will drive the car home with the spool of wire connected. to see how it behaves.

I don't remember, does the valve body have a pressure sensor for the transfer clutch, just as it does for all the other clutches? If not, that really simplifies your life.

i think it does.. but how would it simplify my life ?

 

 

 

anyways drove home cel never came on.

 

had a hard time driving out of my driveway this morning rwd only.

 

at intersections i had a hard time getting moving ! i remember these days of having rwd or fwd cars !

i think it does.. but how would it simplify my life ?

 

You answered it in your test drive, simplifies your life because you don't have to fool the TCU's transfer clutch pressure sensor (if there is one) with the stock PWM solenoid's output as a mirror for the resistance of that sensor. One of my worries for overriding the other solenoids without also addressing the pressure sensors reading different than TCU requested. But that's a more complicated matter for a different time. Glad you have it working! Fun 4WD on demand.

^ ah yes ..

There is a transfer clutch pressure sensor. I was monitoring it just the other day with ROMRaider. I only casually noted it, but had it displayed while monitoring other parameters. Conditions were nothing dramatic, and I only recall seeing a max of about 75 psi.

 

Adjustable center differential and torque converter control, with output to the stock sensors from the MSGPIO to fool the stock ECU would be ideal. Tune-able tables or logic for each would be ideal.

 

In theory you could build a full plug and play piggyback for the 5EAT TCU that could use all of the inputs and trick all of the outputs so the stock TCU never knew any better, with full transmission control via the MSGPIO in the middle.

the transfer clutch pressures are i think requested pressures... because i was playing with it and the pressures went up and down with the engine off! but i played with it some more yesturday and i can drive around with it open or locked and the sport light doesn't flash

 

as for a complete swap to megashift i would load a manual trans rom to the ecu as throttlehappy recomended and then do what ever you want.

 

i wonder if i could get the connectors from the tcu from digikey or similar.. and just replace the tcu with megashift plug it in and change the rom and call it a day. the only things that may not work is the lever position in the cluster ..

 

but megasquirt is now able to talk to stock can dashboards on bmw's and others

Any advance on this?

on?

Sorry mi English is not good enough, but as I understand you was making a control to change the car from Awd to Fwd or Rwd, if this is correct I am glad to know if you succeed and if it will be a terminated products or a diy.

This is the car stuff that amazes me! Amazing work!!

Wow neat project you have taken on.

 

I WISH SOMEONE REALLY SMART WOULD PUT THE TIME INTO REVERSE ENGINEERING THE STOCK TCU SO WE CAN CHANGE PARAMETERS!!!

 

Ok since I shouted that whole statement some genius should soon have a solution for us.

Hey guys, I don't know if this will help, since you have such a car there that one can test such a product.

 

I am starting to work on a built 5EAT 500+whp mustang power legacy and after noting that a lot of CAN research is needed to be done for EMS replacement for the ECU, the TCU could not be replace due to the many outputs and input needed. I was recommended the following TCU without support from them. I am not sure if you all came across it, but please see here. It could be helpful for those who is doing such a project.

 

On the other hand I don't have a CAN car to perform CAN analysis for the TCU operation. Any one having this data that can be worked with a CAN enable EMS?

 

https://www.powertraincontrolsolutions.com/Performance_Aftermarket/Products/Transmission_Products/TCM-2000_Transmission_Controller/

Im not sure what you are saying ?

 

Megasqurt and megashift work with can and yes megasquirt can actually talk directly to a can dashboard on the legacy.

 

What my plan is to make the car think its a manual transmission. And then have a stand alone / tied to megasquirt via can . So no can sniffing and decoding required.

Just saying there are possible alternatives for those who are looking to do what you are doing.

Would it be easier to replace the ECU with megasquirt as well?

 

I run megasquirt in my miata, It's much easier to tune and understand that the subaru ecu...