FORScan Speedo Calibration for larger tires

[jlmotox]

I was just in Forscan last night changing other things and noticed I also have the 422 code, Never saw it the last time I was in there...

I had 200 miles on the truck when I did my tires and lift and Forscan changes, Now at 2,400ish miles, No problems No engine light and my MPH is correct... I wouldn't worry about the code

Sponsored

 

[petulantskeptic]

I have. Changed to the 285-70/17 setting. No codes thrown.

What value did you use for line 726-12-01 xxxx ???? xxxx? What was your default value there?

 

[Mellow]

Just changed mine - disabled auto s/s and adjusted the tire size - tested up to around 60mph and it was matching my phone gps app so all looks good to me...

 

[j0shm1lls]

I gave it a whirl last night,it looks like the speedo is now correct (at least at 40mph, I'll take the freeway home and do some 70mph testing). However, I did get the "U0422 - Invalid Data Received From Body Control Module" DTC, no check engine light. I also tried the PCM relearn, but no joy.

Stock Value
726-12-01 xxxx 0938 xxxx

Changed to (285/70/17)
726-12-01 xxxx 09DC xxxx

Has anyone tried dialing back the tire size, and messing with the axle ratio instead? I've seen some of the F-150 guys have success with that.

 

[RedlandRanger]

I gave it a whirl last night,it looks like the speedo is now correct (at least at 40mph, I'll take the freeway home and do some 70mph testing). However, I did get the "U0422 - Invalid Data Received From Body Control Module" DTC, no check engine light. I also tried the PCM relearn, but no joy.

Stock Value
726-12-01 xxxx 0938 xxxx

Changed to (285/70/17)
726-12-01 xxxx 09DC xxxx

Has anyone tried dialing back the tire size, and messing with the axle ratio instead? I've seen some of the F-150 guys have success with that.

I feel better knowing others have had the same experience I did with my brother's truck. Kind of weird it throws that code, but doesn't seem to affect anything.

 

[PvtZoller]

Done. No codes, no problems after my 5 mile test drive.

 

[FULLSCALE]

Done. No codes, no problems after my 5 mile test drive.

Which tire size and what value did you change to?

 

[RedlandRanger]

Which tire size and what value did you change to?

I was going to ask the same thing - wondering if certain tire sizes throw the 422 code and others are acceptable.

 

[PvtZoller]

Which tire size and what value did you change to?

I will pull some screenshots tonight.

 

[THLONE]

It sounds to me that your computer is just recording that something was changed. And you did.

 

[FULLSCALE]

I will pull some screenshots tonight.

Thanks!

 

[FULLSCALE]

So after reading so much into this and then getting my 265/70R17 tires put on yesterday... I’m not even going to bother adjusting the speedometer. I put my phone in my cup holder on the way home with my speedometer app open and all through town and on the highway home my truck’s speed on the cluster matched almost exactly what my phone was showing.

I know from the factory on most vehicles the speedometer reads slightly high, so it looks like that difference matches the tire size difference nearly perfectly. So as my new tires wear it’ll be closer and closer to the stock size OD so that’s good enough to me!

 

[Mellow]

So after reading so much into this and then getting my 265/70R17 tires put on yesterday... I’m not even going to bother adjusting the speedometer. I put my phone in my cup holder on the way home with my speedometer app open and all through town and on the highway home my truck’s speed on the cluster matched almost exactly what my phone was showing.

I know from the factory on most vehicles the speedometer reads slightly high, so it looks like that difference matches the tire size difference nearly perfectly. So as my new tires wear it’ll be closer and closer to the stock size OD so that’s good enough to me!

LOL.. I should have tried that first... I just assumed it would be off but since I had the stock 255s on I was probably reading even higher. I did the change anyway so either that took or it didn't matter... good test!

 

[Mantis]

So after reading so much into this and then getting my 265/70R17 tires put on yesterday... I’m not even going to bother adjusting the speedometer. I put my phone in my cup holder on the way home with my speedometer app open and all through town and on the highway home my truck’s speed on the cluster matched almost exactly what my phone was showing.

I know from the factory on most vehicles the speedometer reads slightly high, so it looks like that difference matches the tire size difference nearly perfectly. So as my new tires wear it’ll be closer and closer to the stock size OD so that’s good enough to me!

Interesting. I have always been under the impression that you can change your tire diameter up to 3% without it negatively affecting anything and/or requiring a recalibration. Your change is 3.3% so maybe it is close enough? Then again I don't know if what I was led to believe is correct or not either.

Did you also try it with cruise control on? I don't have my truck yet but I assume it is like our Edge in that you set it by a digital speed number. If that set number doesn't match the truck's speed that would be an issue for me.

 

[gfitzge2]

So to everyone that mentions that you get a code when you change the setting. Where does the code show up? Does it cause a CEL? Does it re occur at every start up? Is it always there? Do you need to have your programmer attached to see it? If you change the setting back to factory does the code go away?
I would like to change mine but I don't want to see any messages on normal operation. Thanks.

Sponsored