Setting arbitrary tire sizes for speedometer calibration

Testing new functions
Fresh_1
Posts: 3
Joined: Sun Mar 01, 2020 9:50 pm
Vehicle: 2019 Ford F150 3.5 EcoBoost

Re: Setting arbitrary tire sizes for speedometer calibration

Post by Fresh_1 »

I tried about 20 times today to configure a new tire size in my 2019 F150, and I'm not having any luck. I've tried multiple sizes, I tried adjusting the values directly in 726-12-01 using multiple different known good values and values from the spreadhseet tool, and I tried changing the tire circumference. In every instance, I used the relearn function for both the PCM and TCM, but stull get a U0422 error in the PCM. I switch it back to stock and use the relearn function and the error code is gone and everything is fine. I can't figure out what I'm doing wrong. These are the steps I've been following:

1. Launch Forscan and connect to truck with ignition on, but truck not running.
2. Click on the Chip icon.
3. Click on "BdyCM (AS BUILT format)"
4. Click on the Play icon on the bottom.
5. Enter values for ABCD in 726-12-01 XXXX ABCD XXXX
6. Click "Write"
7. Turn ignition of and back on and click "ok" in the prompt
8. Click on the stop button, aka "Stop Service Procedure" button
9. Click on "PCM Module initialization/relearn vehicle data"
10. Turn ignition off when prompted, click "ok"
11. Turn ignition on but don't start the vehicle when prompted, click "ok"
12. Click on "TCM Module initialization/relearn vehicle data"
13. Turn ignition off when prompted, click "ok"
14. Turn ignition on but don't start the vehicle when prompted, click "ok"

At this point I'm still getting the PCM error code, even if I rest the DTCs and check them again.

I also tried the following:

3. Click on "BdyCM"
4. Click on the Play icon on the bottom.
5. Find the entry for Tire Circumference and enter in the new value
6. Click "Write"
7. Turn ignition of and back on and click "ok" in the prompt
8. Click on the stop button, aka "Stop Service Procedure" button
9. Click on "PCM Module initialization/relearn vehicle data"
10. Turn ignition off when prompted, click "ok"
11. Turn ignition on but don't start the vehicle when prompted, click "ok"
12. Click on "TCM Module initialization/relearn vehicle data"
13. Turn ignition off when prompted, click "ok"
14. Turn ignition on but don't start the vehicle when prompted, click "ok"

I get the same error code using this method.

Any ideas?
lenko
Posts: 601
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

The second method you are using puts the exact same code in that line as the first method. My question is - has the speedometer been corrected? If it has and everything works ok you've likely accomplished what you wanted. I think I have the same error code in my PCM, but this only shows in Forscan and nothing on the IPC. Everything works good, my speedometer is accurate now and I'm not concerned with the DTC.
Fresh_1
Posts: 3
Joined: Sun Mar 01, 2020 9:50 pm
Vehicle: 2019 Ford F150 3.5 EcoBoost

Re: Setting arbitrary tire sizes for speedometer calibration

Post by Fresh_1 »

So after trying unsuccessfully on two different days, I decided to try again today. I didn't do anything different, but apparently the Sun was finally at the correct angle to the Earth, because today it took every size I put in with no error codes. I started smaller, and ended up with the exact size I tried to enter about a dozen times before and it finally worked perfectly. For anyone having issues, my advice would be to wait a couple days and try again.
traske
Posts: 1
Joined: Wed Mar 24, 2021 12:39 pm
Vehicle: F350, 6.7L Diesel, 2021

Re: Setting arbitrary tire sizes for speedometer calibration

Post by traske »

I wanted to advise that I was able to calibrate my speedometer by simply going to the Body Command Module and using the filter and type in "tire". It will bring up a option to change the tire circumference. All you have to do is figure out your new tire circumference in millimeters. Enter it and write in in the program. You can dial in your speed by simply reducing the millimeter number until u are close. And finally when that is finished you run the PCM and TCM relearn programs and then finally delete any DTC codes which there shouldnt be after the PCM and TCM relearn processes. I put 35/12.5/R17 on my 2021 Ford F350 dually and my speedo reads within .1 of actual reading and verified with a GPS app. No DTCs and running perfectly. Hope this helps. It is not necessary to change any As Built codes. When you connect to your truck, you will see the 2 options for BCM As Built and BCM config under the programming function of forscan. Dont use the As Built option, use the BCM config option and filter using tire in the filter bar.
rbentnail
Posts: 82
Joined: Sun Aug 16, 2020 1:10 am
Vehicle: 2013 F150STX 4x4 5.0

Re: Setting arbitrary tire sizes for speedometer calibration

Post by rbentnail »

Fresh_1 wrote:
Sat Mar 20, 2021 2:15 am
So after trying unsuccessfully on two different days, I decided to try again today. I didn't do anything different, but apparently the Sun was finally at the correct angle to the Earth, because today it took every size I put in with no error codes. I started smaller, and ended up with the exact size I tried to enter about a dozen times before and it finally worked perfectly. For anyone having issues, my advice would be to wait a couple days and try again.
:lol: :lol:
Congrats! That's the way I felt about it when it finally worked for me.
Hill208
Posts: 1
Joined: Wed Apr 07, 2021 5:28 pm
Vehicle: F-150, 2.7L, 325, 2018

Re: Setting arbitrary tire sizes for speedometer calibration

Post by Hill208 »

I currently running 285/65 R20 wheels and was wondering what the code to re-calibrate The speedometer
lenko
Posts: 601
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

Hill208 wrote:
Thu Apr 08, 2021 2:15 pm
I currently running 285/65 R20 wheels and was wondering what the code to re-calibrate The speedometer
https://docs.google.com/spreadsheets/d/ ... 2133040050

https://www.binaryhexconverter.com/deci ... -converter

https://docs.google.com/spreadsheets/u/ ... 0/htmlview#

You can enter code, or you can enter tire circumference or you can get code from spreadsheet.
JraySD
Posts: 1
Joined: Mon Apr 05, 2021 7:00 pm
Vehicle: F150, 2.7l, 2018

Re: Setting arbitrary tire sizes for speedometer calibration

Post by JraySD »

I changed my speedo yesterday for a 285/60/20 Toyo AT3 on my 2018 F150 2.7l. I tested it and it was very close. Speedo showed 70mph. GPS showed 70.1mph
I then drove to work this morning and my speedometer was off. At 60mph I was going 72mph. How did it revert back to being off? Please advise.
miller0978
Posts: 1
Joined: Sat Apr 24, 2021 5:04 pm
Vehicle: Ford Focus MK4,1.5 Turbo,182P

Re: Setting arbitrary tire sizes for speedometer calibration

Post by miller0978 »

What field can be adjust for focus MK4 model by forsacn software ?
/* I can't found 726-12-01 and 726-15-01 field on the focus MK4 model.
TX_Jax
Posts: 7
Joined: Wed May 19, 2021 10:06 pm
Vehicle: F350, 7.3L, 1999

Re: Setting arbitrary tire sizes for speedometer calibration

Post by TX_Jax »

Using v2.3.40 -- clicking on the item gives you a drop down menu.

However, choosing in the drop down does not work. I assume the choosing of the item would send the proper parameters to the GEM, but it is not.
Writing to GEM 1 Notation 2021-05-19 143849.jpg
Writing to GEM 1 Notation 2021-05-19 143849.jpg (79 KiB) Viewed 641 times
Post Reply