"learning" transmission.

[mtudb24]

This is probably the dumbest question I have asked, but I didn't have an answer for when a buddy of mine got a brand new gladiator Rubicon and had his dealer put on a Mopar lift and 37" tires. They said they couldn't flash his computer to 37's ( could only goto 35" because that was what the extreme recon JL's come with) but because the truck only had 7 miles on it when the dealer lifted it and the installed the 37's, the TCM will "learn" the drivers habits and driving style and his shift point would adjust itself with the larger tires since it never "learned" with factory tire size.

My dealer flashed mine when I had 35's but bought a tazer to goto the 37's but haven't done it yet and haven't seen any shifting issues yet. Will get around to it at some point soon.

I thought BS on what they told him, but I had no technical reason to tell him that.

Any thoughts?

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[Stan H]

This is probably the dumbest question I have asked, but I didn't have an answer for when I buddy of mine got a brand new gladiator Rubicon and had his dealer put on a Mopar lift and 37" tires. They said they couldn't flash his computer to 37's ( could only goto 35" because that was what the extreme recon JL's come with) but because the truck only had 7 miles on it when the dealer lifted it and the installed the 37's, the TCM will "learn" the drivers habits and driving style and his shift point would adjust itself with the larger tires since it never "learned" with factory tire size.

My dealer flashed mine when I had 35's but bought a tazer to goto the 37's but haven't done it yet and haven't seen any shifting issues yet. Will get around to it at some point soon.

I thought BS on what they told him, but I had no technical reason to tell him that.

Any thoughts?

His speedometer will be off and He will need to adjust tire size in the computer with a tazer or flash cal + but the transmission is in the learn process and they are correct in that part The speed sensor is located in the transmission. Often times the taper or flash cal will have to be set with size size slightly under what the actual size of the tire is or it will have no power at all.
I set mine for 35 and it was like driving a snail. Then I let the flashcal + do a tire wizard calibration and it set the tire size at 33.25 ( tires say 35x12.50x17 ) thing felt like it picked up 50 horse power instantly.
Many guys have posted in here that placing the stated size in with the taper makes it pull terrible and had to lower down the tire size.

 

[ShadowsPapa]

This is probably the dumbest question I have asked, but I didn't have an answer for when a buddy of mine got a brand new gladiator Rubicon and had his dealer put on a Mopar lift and 37" tires. They said they couldn't flash his computer to 37's ( could only goto 35" because that was what the extreme recon JL's come with) but because the truck only had 7 miles on it when the dealer lifted it and the installed the 37's, the TCM will "learn" the drivers habits and driving style and his shift point would adjust itself with the larger tires since it never "learned" with factory tire size.

My dealer flashed mine when I had 35's but bought a tazer to goto the 37's but haven't done it yet and haven't seen any shifting issues yet. Will get around to it at some point soon.

I thought BS on what they told him, but I had no technical reason to tell him that.

Any thoughts?

The dealer has to go by standards, even sales codes. We can use tools like Tazer, JSCAN, ALFAOBD and so on to plug in any size we want, even more accurately.
Get the tire size plugged in there - why put it off? It's just going to have to go through all of this all over again anyway.

His speedometer will be off and He will need to adjust tire size in the computer with a tazer or flash cal + but the transmission is in the learn process and they are correct in that part The speed sensor is located in the transmission. Often times the taper or flash cal will have to be set with size size slightly under what the actual size of the tire is or it will have no power at all.
I set mine for 35 and it was like driving a snail. Then I let the flashcal + do a tire wizard calibration and it set the tire size at 33.25 ( tires say 35x12.50x17 ) thing felt like it picked up 50 horse power instantly.
Many guys have posted in here that placing the stated size in with the taper makes it pull terrible and had to lower down the tire size.

35s aren't 35" - not even close. 33's are typically 32.8 or even a tiny bit less.
Rolling diameter is the key.
IMO, if you make a major change, you need to force a full relearn - just setting the size after a major change and moving on - not good enough.

 

[Hootbro]

Dealership in kind of right in that they are limited to what they could do for tire size changes. Early on for the first year or two back at launch in 2019, the techs could to some degree make changes with their WiTech too like we do with JScan or similar.

Then FCA went to a software subscription model where the dealership techs and their WiTech tool would have those functions ghosted out and they would have to pay FCA a one time software license fee of around $120 to FCA that would give them a code that was VIN specific that would un-ghost their WiTech tool to allow changes. These changes were VIN specific and would now become part of the vehicles official build sheet. That is why they probably cannot go past 35’s in their programming.

The software fee cost plus the dealers labor time cost would make tire programming cost prohibitive for most. There was also the question if it was a one time programming or if the license fee covered any corrections that needed to be made?

 

[legacy_etu]

Dealership in kind of right in that they are limited to what they could do for tire size changes. Early on for the first year or two back at launch in 2019, the techs could to some degree make changes with their WiTech too like we do with JScan or similar.

Then FCA went to a software subscription model where the dealership techs and their WiTech tool would have those functions ghosted out and they would have to pay FCA a one time software license fee of around $120 to FCA that would give them a code that was VIN specific that would un-ghost their WiTech tool to allow changes. These changes were VIN specific and would now become part of the vehicles official build sheet. That is why they probably cannot go past 35’s in their programming.

The software fee cost plus the dealers labor time cost would make tire programming cost prohibitive for most. There was also the question if it was a one time programming or if the license fee covered any corrections that needed to be made?

So annoying. On a vehicle like a Jeep where so many owners change tire sizes this should be a setting in say the Off road pages to allow the driver to change tire size at will.

 

[ShadowsPapa]

So annoying. On a vehicle like a Jeep where so many owners change tire sizes this should be a setting in say the Off road pages to allow the driver to change tire size at will.

As long as it forced a transmission relearn and any other adaptations, yeah. But look at the number of people coming to forums trying to figure out what sizes they should use, among other things. Dumbing it down may cause more problems for those who won't then come in and ask. Like anything else, consider the lowest common denominator...........people will blindly put in 35:and then wonder what's wrong.

 

[Sigz]

The best way to get the right shift points for your transmission is to use a programmer such as tazer or jscan.

I used JSCAN. You can't just input a 35 or 37 into it as most tire sizes aren't true to their size.

Some folks measure and live with that, but what i found to be most accurate is to drive 20miles or so, and use the distance traveled in miles and accurately line it up with the trip distance in my odometer by adjusting the tire size up/down.

Speedometers and radar guns round speed, so I don't like to go off of that. The most accurate method is comparing actual distance traveled. The longer the test run, the better the accuracy.

 

[ShadowsPapa]

The best way to get the right shift points for your transmission is to use a programmer such as tazer or jscan.

I used JSCAN. You can't just input a 35 or 37 into it as most tire sizes aren't true to their size.

Some folks measure and live with that, but what i found to be most accurate is to drive 20miles or so, and use the distance traveled in miles and accurately line it up with the trip distance in my odometer by adjusting the tire size up/down.

Speedometers and radar guns round speed, so I don't like to go off of that. The most accurate method is comparing actual distance traveled. The longer the test run, the better the accuracy.

I used a GPS compared to the trip odo and ended up correct to the tenth after driving 17 miles - took 3 changes with jscan

 

[legacy_etu]

As long as it forced a transmission relearn and any other adaptations, yeah. But look at the number of people coming to forums trying to figure out what sizes they should use, among other things. Dumbing it down may cause more problems for those who won't then come in and ask. Like anything else, consider the lowest common denominator...........people will blindly put in 35:and then wonder what's wrong.

Yeah, totally agree with you here.

 

[pcrawfordpt]

Take a level and place it on top of your tire. Measure down to the ground from the bottom of the level. This will give you your actual tire size for inputting into your programmer. Often up to a few inches smaller than you think…

 

[jhale1800]

Dealership in kind of right in that they are limited to what they could do for tire size changes. Early on for the first year or two back at launch in 2019, the techs could to some degree make changes with their WiTech too like we do with JScan or similar.

Then FCA went to a software subscription model where the dealership techs and their WiTech tool would have those functions ghosted out and they would have to pay FCA a one time software license fee of around $120 to FCA that would give them a code that was VIN specific that would un-ghost their WiTech tool to allow changes. These changes were VIN specific and would now become part of the vehicles official build sheet. That is why they probably cannot go past 35’s in their programming.

The software fee cost plus the dealers labor time cost would make tire programming cost prohibitive for most. There was also the question if it was a one time programming or if the license fee covered any corrections that needed to be made?

It should be a one time license fee. When I upgraded to 35's the dealer first recommended that I get a zscan and update the computer myself. I asked, "and what does that do to my warranty?" He said, "oh yeah, that voids it..."
So, I didn't want to go void my warranty and asked if the dealership could do it for me. The service advisor called it "Asking Mother Mopar," and I paid the $120 to open up the build sheet. At first they just plugged in 35", which was larger than the actual tire size of the BFG tires I was running. They went in with the measurements and updated to the correct size. He said if I ever wanted to go back to the original size or a taller tire, they could go in and make the updates since I paid the fee to "Mother Mopar."

 

[Stan H]

Then once you get past the warranty ya just get a calibration tool do it yourself and forget it

 

[emiddio]

Mine is 2023 sport s gladiator, ecoDiesel, stock size tires/wheels, was told by dealer that is a learning transmission, after 13 months I noticed not liking that it would not up shift to lower gear soon enough, since peak torque is around 1400 rpm, and was not shifting at times to 1700+ would use the manual mode to force like from 4th to 5th, or 5th to 6th, or 6th to 7th, etc; was surprised to see that it "remembered" my preferences for some time after; but not permanently.

 

[JTGuy]

As I recall I set my size at 36.5 with my Tazer for my 37 BFG KO2. Very close to matching my Garmin GPS. I wish it would learn how to go into Reverse correctly when cold.

 

[Stan H]

As I recall I set my size at 36.5 with my Tazer for my 37 BFG KO2. Very close to matching my Garmin GPS. I wish it would learn how to go into Reverse correctly when cold.

I gave up on that as I write this I am having my Transmission replaced @JTGuy mine just literally decided it didn't matter cold hot lukewarm or any temp if it didn't want to it wouldn't

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