How to use FORScan to adjust tire size

[Minotaur1]

Hi folks,

I have a 2018 F150. After following the steps, I end up with a P160A TCM code that I can't clear. I have NO option to Initialize/Relearn my TCM, it simply doesn't show on my Forscan list. I scoured the forums, but have found no solution. I am using the most current Forscan software for Windows, running Windows 11.

Any assistance would be greatly appreciated.

[Mtaylordale]

I have exact same scenario
Adjusted tire size and using windows 10 with latest forscan software I have initialized the pcm but have no option to initialize the tcm. I have IDS and was also unable to carry out any procedure for resets or configuring the tcm I which cleared out the p601a fault for tcm configuration error.
I then attempted to revert to original as built and the error remained. I then accessed the free as built data on fords site and verified within the bcm that all as built data was correct u see the address I changed.
Everything was good but still a configuration error within the tcm. Any assistance would be awesome.

[Minotaur1]

Yes, it's very frustrating as I didn't foresee any issues and I've reprogrammed with Forscan before without any hitches.

I wonder if it's a windows issue? I'm considering doing the Android app but would hate to waste more time accomplishing nothing. But, I really don't want to have to live with a permanent wrench warning/icon either. Also, my transmission gear display disappeared which occurred about 2 days after the failed reprogramming. Which I'm sure is directly related.

Too bad FORscan doesn't have some kind of paid tech support.

On a positive note, my speedometer is accurate.

If you're able to figure this out, please let me know and I'll do likewise.

[Minotaur1]

I found the fix! See below for the link:

https://forscan.org/forum/viewtopic.php ... 822#p85822

Worked with no issues, the wrench is gone!

[Timber911]

Hi all,

I just got my Ford Explorer 2023. When I connected my ForScan and got the data, I found the tire circ was 2437 mm.... Weird since my original tires are 265-65R18 so 2517mm.

Now, I Entered 2558 ,,since I have winter tire. wrote the data and got the 4WD DTC showing... Since I didn't know about the PCM relearn, I rewrote the DATA to 2437mm. Found the process to relearm PCM ( There is no TCM in my version with 2.3.51 (trial test)). reset the DTC and it's fine, no more wrench and DTC showing...

However, is it normal the circumference of the tire in the settings was not the proper mm data from FORD???? Since it should have been 2517 for the 265-65r18 Dueller AT OEM.

Am I the only one with this wrong data and I change back to the proper data mm, will the DTC ever come back? I only have PCM to relearn or need to change tire size somewhere else?

S

[awestcot]

For those like me who had trouble finding the correct info for 2009-2014 F 150's. It is easy but you do it in the GEM module, line726-08-01. It came out right on the money and no codes either.

Any chance you can point me in the right direction of this GEM module? I can’t seem to find it. Thanks!

[awestcot]

I never could find the GEM on this truck. And apparently the 09-10 trucks don't have the exact same computer set up as the 11-14 trucks.

FWIW, I'm working on a 2013 F-150 FX4 and none of the methods described here worked for me for increasing the tire size. I tried ignoring the U0422 code and driving it anyway, but it made no correction at all. Still off about 7%. I tried a smaller circumference than what the truck came with (275/65 - 18) and it took that data without any issue. But, of course, the speedo was even worse off. I tried it just to see if the data I entered was doing anything. It did. The spreadsheet method and entering that into the BCM as built would not work at all for going to a larger size tire. U0422 every time. I tried like heck to get it to accept the highest pre-set value on the list, 315 something, but it would not!! U0422 every time, and no effect on the speedo if I ignored the error and drove it.

The truck has 35x11.50 R20 Nitto Ridge Grappler tires on it. And came with 3.55 axle ratio from the factory. If it were mine, I would be inclined to change to a lower ratio, but I was just trying to help a friend with the speedo issue. The PCM was only happy if I set the BCM to the original tire size, or smaller. I finally decided to set it back to the OEM size tire and change the BCM axle ratio data (not as built) to the pre-set value of 3.31 and give it a whirl! Bingo! Speedo is dead on now. I'm sure I'll get shunned by some of y'all for doing this, but it worked! I honestly believe the shift points are still in a good place. It's not like there is an enormous difference between 3.55 and 3.31 anyway IMHO.

[tractmec]

For those like me who had trouble finding the correct info for 2009-2014 F 150's. It is easy but you do it in the GEM module, line726-08-01. It came out right on the money and no codes either.

Any chance you can point me in the right direction of this GEM module? I can’t seem to find it. Thanks!

If you are looking for a GEM module in the 2005(Forum signature) and up to 2010-12 F150(Gasoline and Flex Fuel) you can stop wasting your time as those Model Year F series do not have a GEM module and all Tire size and Axle ratio settings are in the PCM VIN ID block and will require an adapter that is FEPS capable(Flash EEPROM Programming Signal, Consisting of 18 volts applied to DLC Pin 13 This pin being present in the DLC is a good indication)!

This applies to to F series(Gasoline engines) and some Car lines up to mid~ 2012(my 2010 Fusion is this type)! FORScan can access this block with 2.4.6Beta from about 2009 and up with a VCM2 or a vLinker FS.

FORscan cannot access this block in 2008 and older as of yet with FORScan Version 2.4.6Beta(FEPS PCM) and a VCM2 or a vLinker FS adapter(FS means FEPS capable) but it is being worked on!
These Model Years(08 and down) still require Ford IDS version 86(what I use) or higher and a Ford VCM 2 adapter(Or an FEPS capable J2534-2 adapter And Ford FJDS) in order to access programming in the PCM!

There is also a further complication in the fact that there is a network protocol(called UBP) in these model years that FORscan can access and read but it requires a FORD VCM 2(just for your information and does not pertain to this particular discussion)!

Even most J2534-2, the OBDlink EX and the vLinker FS cannot access the modules on this network (UBP and in your 2005 F150 case it is the Vehicle Security Module containing functions such as RKE among other security functions and possibly others like heated/cooled seats, Electronically controlled HVAC, depending on Trim Level)! This was in use in the F series up to~ 2008-2009.

Just in case you are wondering what you are doing wrong!

[awestcot]

WOW! Thanks for the very in depth response! In this case I was working on a 2013 F-150 for a friend. I was finally successful in getting the speedometer accurate, but in a little round about way.

I have an SCT Livewire tuner on my 2005 F-150 that has allowed me to easily adjust for tire size and a gear ratio change that I have done to my own truck. As well as custom tunes of course. I invested in that several years ago, and it has been a great asset to my truck. I favorite thing about it is the live data gauges it displays. This is awesome because I keep a transmission temp gauge displayed all the time.

[KyFordMan]

I had issues with my speedometer being off after changing the tire size in FORscan and after some research I found when you get your tire circumference in mm's you need to times that number by .967 and use that number in FORscan. I am not sure why this is but it is the formula that was used to determine the number for the as built OEM tires. You will still need to relean the PCM after the change.