Gen 4 swap into 88 Wagoneer speed sensor/shift help

Not sure where to post this or if it's even allowed but figured I'd try some help here over the weekend, thank you!!
Hey everyone, just finished an LS swap Gen4 08 5.3/4L60e using original NP229 from 88 Grand Wagoneer
I'm using the Dakota Digital Pass through 8000PPM generator (sen-01-4160) through the speedometer cable to generate speed sensor signal since the NP229 doesn't have a speed sensor.
This creates a 8000 PPM signal
I bought the Dakota Digital SGI-100BT which now takes that 8000 PPM signal and turns it into 126000 PPM for GM LS ECUs that they require.
My tuning guy also updated the E38 ECU with the Tire height and gear ratio (he did not do the Trans ECU just the E38)
The Jeep is driving and idles fine, shifts out of first too early most of the time, but shifts great otherwise, upshifts are good and will wind out the gear if I hold it down.
Problem: NO downshifts while cruising weather part throttle or full throttle??!! IT just takes off in that current gear (which is OD) cause i can manually drop it into 3rd and notice the difference right away.
I've adjusted/calibrated the SGI-100bt signal while driving to match the actual speedometer speed/GPS speed and that didn't help any at all. (my scantool was reading the trans mph speed at 74mph when the actual vehicle speed was 50mph, so this is now fixed and both reading together).
Anyone can help figure out what to do from here? Is this a HPTuning issue now or anyone know if there's more to do with this SGI-100bt unit to make all this work properly. Dakota Digital Tech guy was of no help at all other than telling me it's not going to work even though they sold me the products lol (morons).
Thank you to anyone for help..

SO your running a 4L60E, are you using a T42 TCM?
You mentioned he tuned the E38 but not the TCM.. The TCM needs to be tuned to the tire/gear combo for any shifting to work halfway correctly.
E38 has nothing to do with the transmission itself. But it does give it data to communicate together.

yes it's the T42 TCM and he has only tuned the ECU, hoping it would work, next will be the TCM. Will that fix my issue as in you believe that's the main reason why it's not working? Dakota tech people telling me this unit won't work for "controlling" the shifting with this VSS unit they sold me but I've read on some LS swap forums that with tuning it can be made to work if the tuner knows what he's doing and does the math correctly. thank you for your help

I should reword it to say I was hoping tuning the ECU would work lol, he mentioned that most likely the TCM would have to be seperately tuned as well when I told him of the downshifting issue and 1-2 shift being so quick.

Wait so your tuner thinks tuning the gear ratio and tire size in the ECM is going to change how the transmission shifts without touching the transmission tune?
IF the TCM is setup for 3.08 gears and 31" tire and your running 4.88 gears and 35" tires then yea its not gonna shift worth a crap.

The Dakota digital setup needs to report the data accurately to the TCM/ECM. Then the TCM needs to be tuned to use that data correctly.

Reading the ECM VSS, TCM VSS, and the dakota digital all need to be correct and it will work fine.

like I said, he tuned the E38 for the right tire size and gear ratio when he initially did the VATS/Emission stuff...according to Dakota digital it should work without having to mess with "tuning the TCM" since their unit outputs the correct 128k ppm signal that a stock 4L60 is looking for...but of course it's not haha, nothing ever works like it's supposed to from these aftermarket companies

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Originally Posted by 971TonCrawler

like I said, he tuned the E38 for the right tire size and gear ratio when he initially did the VATS/Emission stuff...according to Dakota digital it should work without having to mess with "tuning the TCM" since their unit outputs the correct 128k ppm signal that a stock 4L60 is looking for...but of course it's not haha, nothing ever works like it's supposed to from these aftermarket companies

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I dont think you understand how this works.
If the T42 has a factory tune for 3.08 gears and 31" tire, And your combo doesnt match that, it will need to be tuned.
Has your "tooner" been Tooning for awhile or is he a newbie?

Who knows what gear/tire combo the TCM is programmed for.

Both will need to be tuned together. As far as we know the tuner is explaining this clearly but he just doesn't understand.

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Originally Posted by 971TonCrawler

Not sure where to post this or if it's even allowed but figured I'd try some help here over the weekend, thank you!!
Hey everyone, just finished an LS swap Gen4 08 5.3/4L60e using original NP229 from 88 Grand Wagoneer
I'm using the Dakota Digital Pass through 8000PPM generator (sen-01-4160) through the speedometer cable to generate speed sensor signal since the NP229 doesn't have a speed sensor.
This creates a 8000 PPM signal
I bought the Dakota Digital SGI-100BT which now takes that 8000 PPM signal and turns it into 126000 PPM for GM LS ECUs that they require.

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Your build has violated PPEI requirements for transfer case control and speed sensing. Look for GMW3119.

Start from scratch, use closest gear/tire RWD calibration for a start.

I understand perfectly fine, this ain't my first rodeo, I've done over a Dozen LS swaps but I've never used a old Tcase that didn't have a VSS so hence my issue since I had to use this Dakota Digital VSS generator and converter....
and btw, I've done many LS swaps that ran and drove perfectly fine without "tuning" the tire/gear ratio until I was able to drive it back to my tuner to correct such things....that's not the issue I'm having. Sorry but tire size and gear ratio being off doesn't stop a transmission from shifting at all or starting in 2nd and no downshifts.
I was trying to get help from anyone familiar with this module from Dakota and see if there's a different way to wire it for the signal to work...
And I already mentioned the ECU was tuned for the right gear/tire combo and didn't make a difference ...and on Gen 4 and Gen 5 you can tune the trans tire/gear ratio on the ECU without having to separately tune the TCM if they came from the same vehicle which he's already done like stated...I'm waiting for him to free up time to go and now actually plug into the TCM and start messing around with the pulses and revolutions to hopefully accept the output that this Dakota unit is putting out..Dakota techs are baffled and have no idea what to do from here other than let the tuner figure it out (go figure lol, useless)

Gear/tire is irrelevant, it is just more convenient to start with closest VSS/OSS ratio. My point is you have to start from RWD calibration.

Since your trans is 4WD it is likely ECM and TCM are came from the same vehicle with 4WD calibration. But your combo is missing TCCM which gets transfer case speed sensor signal and transmits it thru GMLAN to ECM and TCM along with TC mode.

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Originally Posted by verlon

Gear/tire is irrelevant, it is just more convenient to start with closest VSS/OSS ratio. My point is use have to start from RWD calibration.

Since your trans is 4WD it is likely ECM and TCM are came from the same vehicle with 4WD calibration. But your combo is missing TCCM which gets transfer case speed sensor signal and transmits it thru GMLAN to ECM and TCM along with TC mode.

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that makes sense, thanks. Hopefully today my tuner is available and get this thing done. It shouldn't be a big deal for him he knows all this stuff. Everything I've been asking was in hopes to "see" if there's something to be done with this Dakota module to make it works since they kept telling me "it should be working" lol.
(I've learned my lesson, stick with using Chevy Tcases that have VSS in them like a normally do haha)

man something is really really weird going on with this pulse generator/SGI-100bt unit.
for the record, my Tuner guy is a pro at hot rods/nascar/street cars and high performance stuff..been at it for 20+ years, has a full dyno shop and all!! He knows his stuff!!
BUT he's never had to tune with one of these VSS pulse generators and because obviously it's not communicating like Dakota people keep saying "it should work" well today we spent 3 solid hours, he tried anything and everything...seriously tried stock 2wd tune, stock 4wd, even copied numbers that a guy on a thread here used in his build and nothing changed...shifting never changed, still no downshifting when applying any throttle,...
It drives but it's like in Limp mode but it's not...pretty much grandma gears and throttle and that's it.
I'm baffled, he's baffled that nothing he did worked
I do remember when he pulled Data log the ECU was seeing the speed that matched GPS/speedometer but it's like not using that signal to make the trans do proper work...any help that I could relay to my tuner please?!!
I AM NOT A TUNER lol, so bare with me if you try and explain things to me that are probably going to go over my head haha. I do fab work and LS swaps full time so electrical and tuning isn't my thing at all. Thank you for any help

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Originally Posted by 971TonCrawler

I do remember when he pulled Data log the ECU was seeing the speed that matched GPS/speedometer but it's like not using that signal to make the trans do proper work...any help that I could relay to my tuner please?!!

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That's not your primary goal.

I think I know what's wrong.
TCM must get accurate OSS signal. And the first thing you have to do is adjust pulse converter so that OSS will be accurate.
Place trans in 3rd gear and compare ISS and OSS, they must be the same, not 1% accurate, not 0.2% accurate, exactly the same.
If you know Transfer Case speedo cable gear ratio use calculated coeffs for pulse converter rather than measured error.
TCM uses ISS and OSS to control gear slip, perform various diagnostic checks and so on. It behaves like hell when ISS or OSS signals are present, but not accurate.

When you get accurate OSS adjust tire/gear in ECM and TCM to get accurate speedo.

Thats what i was explaining in post 5.
Ive fixed a ton of tunes where the vehicle speedo is correct but the tooner didn't adjust the TCM to reflect the correct speed.
TCM doesn't care what ECM shows or the vehicle speedo on the dash shows. Its going to shift based on what its internal speed is calculated.

thanks guys for the info, bare with me as I try and understand this stuff over the weekend so Monday I can have a plan of action with my tuner.
So according to my research, the 2008 4L60e has an ISS(internal speed sensor)?!? so what you guys are saying is that it needs to match what the OSS (Output speed sensor) is putting out?? correct?
I did confirm the SPeedometer gear on the transfer case is 26 tooth which according to another friend of mine, he says that puts out exactly half the speed of the Output shaft revolutions. So how does knowing this affect the VSS Pulse generator?? that supposed to put out 8000PPM from dakota digital. thank you very much for yalls help

If you know Transfer Case speedo cable gear ratio use calculated coeffs for pulse converter rather than measured error..

When you get accurate OSS adjust tire/gear in ECM and TCM to get accurate speedo.[/QUOTE]
Thank you very much, now that I know my speedometer gear in the T-case is 26 Tooth, (which according to a friend he says it puts out exactly half the speed of the Output shaft revolutions) how does that affect the SEN-01-4160 Pulse generator that supposed to put out 8000ppm signal to the SGI-100bt module?
I'm sorry, I'm good with fab work/installing and such but when it comes to reading comprehension and technical stuff I'm very slow learning (english second language lol).