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5EAT TCU Reverse Engineering


utc_pyro

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Not yet, just slowed down. I'm going to have a weak worth nothing to do after work soon, and I'm going to be spending most of that time sitting in my car hammering on my TCU to at least get logging support.

 

For the "hacking" portion, I'm going to have to get friendly with the techs at my local dealer so I can intercept the flash being loaded onto the TCU. I'm still picking out a logic analyzer for that (suggestions welcome!).

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  • 3 weeks later...

Not yet, I'm having problems finding a program that I can use manually send commands via ssm to find it's address. Any .NET devs willing to wip me something up? I just need someth I can type hex commands in to send out my OpenPort.

 

I have come up with some some ideas for a piggyback, memory hack (it stores info in an EEPROM/Flash in the valve body) or hacking the valve presure regulating chip to rase the pressure.

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It has a fixed target address (the ECU's), I need to sweep the target addresses to find the tcu.

 

That said I have a program to try, so I'll keep you all updated. I took a shot at it last night and couldn't get it to talk to my cable though :/. May be driver related, I'm going to try my old XP laptop tonight.

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  • 2 weeks later...
I have come up with some some ideas for a piggyback, memory hack (it stores info in an EEPROM/Flash in the valve body) or hacking the valve presure regulating chip to rase the pressure.

 

 

I had noticed the mention in the manual of storing data in a memory inside the trans. but hadn't got around to posting about it. If you could figure out what is stored there, it might not be too difficult to hack it such that the TCU thinks it needs to shift quicker based on what it reads.

 

Another thought - Do the JDM or EDM versions of the LGT use a different TCU? Possibly one that shifts quicker / more firmly? I don't recall non-US/Canadian drivers complaining about the trans. I must admit though that I haven't done any type of searching to determine if this is more than just a notion on my part.

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I had noticed the mention in the manual of storing data in a memory inside the trans. but hadn't got around to posting about it. If you could figure out what is stored there, it might not be too difficult to hack it such that the TCU thinks it needs to shift quicker based on what it reads.

 

Another thought - Do the JDM or EDM versions of the LGT use a different TCU? Possibly one that shifts quicker / more firmly? I don't recall non-US/Canadian drivers complaining about the trans. I must admit though that I haven't done any type of searching to determine if this is more than just a notion on my part.

 

That's kind of what I was thinking. I have yet to figure out what the heck the controller used in the TCU is based on, so that makes it rather hard to start hacking it. If the memory chip in the valve body is "standard" enough for me to get a speck sheet on, we can at least take a look at it. Based on the description in the tech documentation of the 5EAT I dug up, they just use this for the "starting point" though and the TCU will learn around it.

 

On the JDM/EDM TCU, it might work. If I get the time, I'll try and plug this '05 TCU into my '06 to see if they lock the ECU year to the TCU one.

 

Any one have a trashed valve body they can take pictures of?

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That's kind of what I was thinking. I have yet to figure out what the heck the controller used in the TCU is based on, so that makes it rather hard to start hacking it. If the memory chip in the valve body is "standard" enough for me to get a speck sheet on, we can at least take a look at it. Based on the description in the tech documentation of the 5EAT I dug up, they just use this for the "starting point" though and the TCU will learn around it.

 

On the JDM/EDM TCU, it might work. If I get the time, I'll try and plug this '05 TCU into my '06 to see if they lock the ECU year to the TCU one.

 

Any one have a trashed valve body they can take pictures of?

 

I have a stock valve body on my shelf. What do you need pictures of? I know I'm going to kick myself later if I tear it apart, so keep that in mind. Let me know.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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I have a stock valve body on my shelf. What do you need pictures of? I know I'm going to kick myself later if I tear it apart, so keep that in mind. Let me know.

 

I've never seen a good high res shot of it, so it's hard to tell. I think there is a box with a bunch of wires going into it on the bottom center. From the tech info, it calls that the memory box. You wouldn't even be taking the valve body apart to get pictures of the inside of that box.

 

Though if you want to take the entire thing apart, go for it! Detailed pics of the inside could help for mechanical mod potential. Particulary the chance of using a 350z shift kit on it.

Edited by utc_pyro
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Oh I'm sure I could mod them myself if I had the time and inclination. But that's not realistic now. I don't know enough right now anyways. But I can snap some photos.
[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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  • 3 weeks later...

I want to change some parameters in 08+!!!!:spin:

I want the throttle position n/a for downshifting (current no throttle to downshift to 1st @ 32mph, I sometimes have super light throttle and like to downshift, track use)

Maybe bump up the downshift mph to 1st since 08+ have rev match, 3rd to 2nd does over 4300k rpm downshift iirc, 1st not so high

5eat downshift rev match:):wub:

Powder coated wheels: completed:)

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I think the rev matching is done in the ECU, not the TCU. As in the TCU tells the ECU to do it, but the amount is probably in the ECU. You might want to check over on RomRaider to see if they can dismissible that portion of the ECU further for you.

 

Progress report: I'm designing a piggyback for the short term to act as a shift kit. It wont be able to change shift points, but it can speed them up and increase pressure. It can also keep that lockup from happening at WOT that killed a few transmissions. Right now I'm working on the pinout of the control wires to the valve body (not broken out in the service manual) and I'll post that when I have it finished.

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Just to be clear, are there set in stone downshift points, or does the TCU choose when to shift based on various data such as vehicle speed, load, what the G sensor is saying, etc. Edited by fishbone
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I was gonna start a new topic, unless if someone on here wants to try it out since Im not near my car...

 

I was looking at AccessTUNER Race (COBB) and you can change the 'Gear Determination' it looks like, it uses numbers I dont understand Im a noob in tuning... And Im away from my car till Aug so I cant change and see

 

Pics Gear Determination is diff in all, Look to left column

 

http://i596.photobucket.com/albums/tt49/underground000/Shift.png?t=1278228190

http://i596.photobucket.com/albums/tt49/underground000/Shift2.png?t=1278228401

http://i596.photobucket.com/albums/tt49/underground000/shift3.png?t=1278228437

Edited by underground000

5eat downshift rev match:):wub:

Powder coated wheels: completed:)

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  • 2 weeks later...

Dont know if this helps, something I found going through vaca pics on 08 LGT

 

http://i596.photobucket.com/albums/tt49/underground000/08.png?t=1279375335

 

http://i596.photobucket.com/albums/tt49/underground000/Pressure.jpg?t=1279377851

Edited by underground000

5eat downshift rev match:):wub:

Powder coated wheels: completed:)

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Dont know if this helps, something I found going through vaca pics on 08 LGT

 

http://i596.photobucket.com/albums/tt49/underground000/08.png?t=1279375335

 

http://i596.photobucket.com/albums/tt49/underground000/Pressure.jpg?t=1279377851

 

It's not bad, but that's the info for the 4eat not the 5eat. Though, that said, I think the pinouts are similar. If you look at the 5eat in the service manual (and that other documentation I dug up) it just shows them going from the TCU to a "block" of the valve body. Unfortunately, not nearly the same level of detail as they give for the 4eat. Though that said, the info about the line pressure is interesting, as it's probably the same between them. I was thinking we needed to RAISE the current, but this info is showing the opposite.

 

Hum, if one puts a resistor in parallel with the coil, you'll get higher line pressure!

 

Just to be clear, are there set in stone downshift points, or does the TCU choose when to shift based on various data such as vehicle speed, load, what the G sensor is saying, etc.

 

Unsure on that, but if you look at some of the detialed information on the transmission, there are a few graphs of the shift points. They are not that detailed, but look very close to those found when they hacked the SVX's TCU. It's based on engine load and MPH, and there are some points that go to "0" on the throttle, so that would be the set in stone portion. Unlike a human driving a manual, the TCU is actually shifting based on MPH, so it would be set speed points. It changed maps has some shift logic incorporating the g-sensor, but I don't think it's a major impact on normal shifting.

Edited by utc_pyro
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Hum, if one puts a resistor in parallel with the coil, you'll get higher line pressure!

 

Thats one of the things IPT does in valvebody mod. I read somewhere that the first guy that had the IPT had an external resistor so if they needed to they can change the resistor quickly (without dissassembly)

5eat downshift rev match:):wub:

Powder coated wheels: completed:)

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