Speedometer correction flash file from Mopar?

[zouch]

anyone have handy the routine for getting the code created by the factory to flash their J**p to adjust for tire size and/or gearing updates? (i'm not interested in any of the aftermarket tuners, Tazer, JScan, etc.)

the only dealer i ever discussed it with that seemed to know anything about it has closed, and i'm going to have to educate another one.

last i recall there was a form the dealer had to fill out with Mopar and a charge to have the code created for your vehicle, but i can't seem to find any of the details here anymore.

@JeepCares

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[Barney392]

anyone have handy the routine for getting the code created by the factory to flash their J**p to adjust for tire size and/or gearing updates? (i'm not interested in any of the aftermarket tuners, Tazer, JScan, etc.)

the only dealer i ever discussed it with that seemed to know anything about it has closed, and i'm going to have to educate another one.

last i recall there was a form the dealer had to fill out with Mopar and a charge to have the code created for your vehicle, but i can't seem to find any of the details here anymore.

@JeepCares

Curious why you are not interested in using JScan?

 

[mark090852]

I recently had that done for my 2020 JLU Rubicon at my local Jeep dealership here in Western Colorado. I bought the vehicle used at a different Jeep dealership and it came with 35s but had never been calibrated for the larger size tires. I took the vehicle back to that dealership 50 miles away where I had purchased it to see if they would do that calibration for me and they had no clue at all as to how to do that. I even spoke with the service manager and she said they couldn't do it. Said I would have to buy an aftermarket "device" and do it myself. I tried to explain to her that dealerships do that all the time, re-calibrate for tire size or led headlights and various other things. I felt like I was speaking to deaf ears.

So, I took it to the dealership here in town and they instantly knew what I was talking about. They had me bring it in the next day and they re-flashed the computer for me and charged $140. I could immediately see the change in the speedometer readings and in the reported gas mileage. It's a piece of cake for them to hook it up to their computer and make the changes necessary. Any knowledgeable dealership can do it.

 

[BigMaCro]

Lol, you all are talking like it's a huge complicated process - flash firmware? factory file? nope.

All that's necessary is to adjust parameters. These vehicles are built with many different options and it is a very quick process to just change the gear ratio and tire size in the ABS module.

It is very simple to do it with Jscan. for less than $50 you can have the bluetooth dongle and app.

I bet you're confusing the dealers by demanding going to the factory for some sort of software package.

 

[zouch]

i have no interest in adding the variable of an aftermarket device if i can avoid it; i would prefer the vehicle provide the basic function of indicating speed on its own.

obviously many people (including dealerships) don't know correction has ever been possible, and most of the info i've found about it here is several years old (reference the links at the bottom of this page, and this one); and this is an example of one of the old Mopar bulletins about it.

i was hoping to find some more recent experiences and detail as i heard there had been some changes since then, and possibly a break in the vehicle firmware at some point about late 2020 or 2021.
thanks for your input @mark090852!

Curious why you are not interested in using JScan?

 

[2nd 392]

After 4.56’s and 35’s I was told they couldn’t recalibrate. After service 4WD output shaft speed-wheel speed diagnosis a different service writer (who appears to be trying) updated vehicle sales code to the recon package. The code hasn’t come back but the speedometer is still off and it doesn’t disable MDS in OR+ like XR’s either. They had it from Tuesday to Friday going back and forth with engineering, one promising lead failed. Brought it home while he pursues a couple ideas. WTF is so difficult when it’s a Factory Option ?! ? If successful I will report in the Drivability in OR+ thread under 392.

 

[mjg4xe]

I recently put 35s on mine while at the dealer for other service - they said they could make the tire change themselves but then realized when trying to do it I would have to pay ~$150 for them to unlock my VIN with Jeep. At that point I just went with the Jscan route - it truly is easy to do yourself and will cost you ~$100 for the license, security bypass cable and OBD device. You don't need to leave anything plugged in, you are just using it to access the Jeep's computer to make the necessary change.

 

[Ratbert]

i have no interest in adding the variable of an aftermarket device if i can avoid it; i would prefer the vehicle provide the basic function of indicating speed on its own.

obviously many people (including dealerships) don't know correction has ever been possible, and most of the info i've found about it here is several years old (reference the links at the bottom of this page, and this one); and this is an example of one of the old Mopar bulletins about it.

i was hoping to find some more recent experiences and detail as i heard there had been some changes since then, and possibly a break in the vehicle firmware at some point about late 2020 or 2021.
thanks for your input @mark090852!

With JScan or AEV's ProCal you simply make the change in your Jeep's settings then remove the device.

 

[five9dak]

Get JSCAN and a bluetooth cable. Cheaper than an hour of dealership labor.

 

[Aturking]

I was shocked that my dealer had no idea how to do this also. From the research I have done, Jeep sells a software called Mopar Custom Calibration. Its technically an add on from the Mopar Vehicle Protection and that software allows them to make parameter changes on gear ratio and tire size. The actual software is $150 dollars and then 1 hr labor on top of that. I was quoted like $360 bucks from another dealership. When my dealer is doing my 19A clutch recall and they're going to hide the labor for me, but I have to buy the software.

 

[yokramer]

anyone have handy the routine for getting the code created by the factory to flash their J**p to adjust for tire size and/or gearing updates? (i'm not interested in any of the aftermarket tuners, Tazer, JScan, etc.)

the only dealer i ever discussed it with that seemed to know anything about it has closed, and i'm going to have to educate another one.

last i recall there was a form the dealer had to fill out with Mopar and a charge to have the code created for your vehicle, but i can't seem to find any of the details here anymore.

@JeepCares

Dont you mean @J**pcares?

 

[zouch]

from what i've read (some of which i've linked), the cost to the dealer was $100, they were supposed to charge $125 and there was a code they could use to bill 0.2 hours of labor.

i'm not shocked your dealer doesn't know (it doesn't seem to be something many people/dealers have familiarity with). on top of that it's apparently changed a couple of times.

I was shocked that my dealer had no idea how to do this also. From the research I have done, Jeep sells a software called Mopar Custom Calibration. Its technically an add on from the Mopar Vehicle Protection and that software allows them to make parameter changes on gear ratio and tire size. The actual software is $150 dollars and then 1 hr labor on top of that. I was quoted like $360 bucks from another dealership. When my dealer is doing my 19A clutch recall and they're going to hide the labor for me, but I have to buy the software.

 

[Chrisbayridge1]

I recently had that done for my 2020 JLU Rubicon at my local Jeep dealership here in Western Colorado. I bought the vehicle used at a different Jeep dealership and it came with 35s but had never been calibrated for the larger size tires. I took the vehicle back to that dealership 50 miles away where I had purchased it to see if they would do that calibration for me and they had no clue at all as to how to do that. I even spoke with the service manager and she said they couldn't do it. Said I would have to buy an aftermarket "device" and do it myself. I tried to explain to her that dealerships do that all the time, re-calibrate for tire size or led headlights and various other things. I felt like I was speaking to deaf ears.

So, I took it to the dealership here in town and they instantly knew what I was talking about. They had me bring it in the next day and they re-flashed the computer for me and charged $140. I could immediately see the change in the speedometer readings and in the reported gas mileage. It's a piece of cake for them to hook it up to their computer and make the changes necessary. Any knowledgeable dealership can do it.

My dealership wants 200 bucks

 

[Ratbert]

If you're adamant about avoiding aftermarket solutions then how about AEV's ProCal SNAP? It's technically still aftermarket, but it was bundled with the 20th anniversary edition Jeeps. Not exactly cheap at $225, but you can use it again when you change tires or gears next time. Note that it doesn't stay connected after changing those settings.

https://www.aev-conversions.com/product/procal-snap/

 

[rcadden]

I understand your hesitancy to introduce an aftermarket/3rd party variable into the mix. I had the same hesitation.

However, it's helpful to understand how these things work, as you'll have less headache and save some $$.

The Tazer is designed to permanently connect to your vehicle (marry). Whenever your vehicle boots up, the Tazer will run and re-implement any of its programmed "live" features. IMO, this is more risky - changes are being made basically every time you start your vehicle.

JScan is not designed to do this. JScan is just a consumer version of essentially what your dealership is going to do. While your vehicle is running, JScan allows you to read the current data entry for a particular field, and then change it and save it.

So, for instance, right now your speedo is programmed for 31" tires. JScan allows you to simply tell your vehicle that particular data field should be 33" instead of 31. It writes the new value, saves it, and it's done until you change it again. You can even remove your ODBII dongle to fully disconnect JSCan - it's not a live/permanent solution.

NOTE: Tazer has some similar write-and-save features, but it's more $$ and IMO not worth it if you're not going to use the live features.

TL;DR - understand the hesitation/caution (which is wise) but a solution like JScan is cheaper, more convenient, more capable, and allows you to avoid having to drop your vehicle at a dealership for an hour for them to do a 5-minute task.

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