FORScan Speedo Calibration for larger tires

[PonyXpress]

Thanks for your post. There for sure seems to be two options, BCM change or the mm change, and it seems people are reporting that both work.

Did you also have 285/70/17 tires and did you use 2610 mm?

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[RoadBoss]

Thanks for your post. There for sure seems to be two options, BCM change or the mm change, and it seems people are reporting that both work.

Did you also have 285/70/17 tires and did you use 2610 mm?

the mm change is super easy, it's right on the menu, spelled out in english text. I wasn't even planning to adjust it, but I came across it while looking for other options and decided i might as well give it a try.

and no, different tire size. I am running 235/85/16 cooper ST max, which is exactly 32", when new at least. I entered 2500mm, they are supposed to be around 2520mm new. the factory setting I believe was at 2320mm.

 

[PonyXpress]

I changed the mm too, the speedo is perfect. For others to reference, here is what I tried:

My new setup is 285/70/17 Falken Wildpeak AT3W, the factory mm setting was 2360 and the speedo was reading slow by 4 or 5 mph. That is not good because you are going faster than you think.

I tried 2610 and it was 3 miles slower, while safe because you are going slower than your speedo shows, I changed it again. I tried 2500 and it is almost dead on. It might be 1/2 mph faster than I'm actually going, so safe and accurate.

I forgot to check for DTC codes until I was done changing the mm. I found that I do have a few codes listed, but I'm not sure when they showed up. It could have been after doing the 3" front lift, or after I installed the new wheels and tires.

PCM U0422:00-2F This DTC sets when network DTC concerns occur during module to module communication. it says check for other DTC codes

BdyCM B124B:15-48 I couldn't find anything about this one.

BdyCM B124A:15-48 I found this, but not sure it's correct: Driver Blend Door Short to Ground

BdyCM B1336:01-08 I found this, but again, not sure if it's correct. I did have my driver door open: Door Ajar

I will use FS again to see if I can clear them out, and if there is anymore details. I forgot to try to click on each one while I was in there.

 

[Mugatu]

Hi Everyone;

After lurking on this thread a while, I finally got a new set of wheels and tires. I went with a slightly larger size of 33x12.5x18 tire size and thought I'd share my results.

According to the data I found on my tire size, the circumference is listed as 2635mm. Adjusting to 2635mm in FORScan, my speedo was reading 4-5mph too fast. I ended up having to scale down to 2510mm which I thought was interesting considering how far off it was.

After dialing in the speedo, I also got the PCM U0422:00-2F. I also have a couple of edits to my truck aside from this.

Crewcab FX4 Lariat
Tires: Toyo Open Country R/T (33x12.5x18)
Wheels: KMD 541 Dirty Harry in textured black (18x8.5 0mm offset)

https://www.ranger5g.com/forum/attachments/612995753-jpg.45590/

 

[RangerRaptor]

Hi Everyone;

After lurking on this thread a while, I finally got a new set of wheels and tires. I went with a slightly larger size of 33x12.5x18 tire size and thought I'd share my results.

According to the data I found on my tire size, the circumference is listed as 2635mm. Adjusting to 2635mm in FORScan, my speedo was reading 4-5mph too fast. I ended up having to scale down to 2510mm which I thought was interesting considering how far off it was.

After dialing in the speedo, I also got the PCM U0422:00-2F. I also have a couple of edits to my truck aside from this.

Crewcab FX4 Lariat
Tires: Toyo Open Country R/T (33x12.5x18)
Wheels: KMD 541 Dirty Harry in textured black (18x8.5 0mm offset)

https://www.ranger5g.com/forum/attachments/612995753-jpg.45590/

The OEM tires don’t match the mm size in the configuration either. The calculator has them at 2438, but the setting from Ford is 2360. I get the PCM error when I adjust the tire size for my 285/70R17 BFG KM3s. I can clear it but it always comes back. If I change it back to factory, I get the PCM error, but I can clear it and it doesn’t come back.

 

[RoadBoss]

I think the issue is that the tires flex when there's weight on them, so the effective rolling diameter /circumference is smaller than the overall inflated tire with no weight.

could be fun to figure out exactly how much the sidewall compresses under the weight of the truck and see if it matches the speedometer error.

 

[Gibbs314]

Not sure how to fix it but here is what I found on the U0422 code.

SCCM U0422:00 Invalid Data Received From Body Control Module: No Sub Type Information This DTC sets when SCCM recieves an invalid message from the BCM.

It looks like the value is also stored within the SCCM or maybe there are only a few default values allowed? Maybe there is a way to do an SCCM relearn or change the value in the SCCM to match? Not sure but thought this might help as I hadn't seen anyone mention the steering column control module with this code.

I will probably put larger tires on my truck some day so hoping maybe someone figures this out.

 

[TheKracka]

When calibrating by circumference I wonder if taking 3.2% from the calculated circumference is the formula since that's the difference of the factory setting of 2360 vs calculated 2438. With that said if running 285/70/17 3.2% of 2610 would be 2526. Going to try this tomorrow.

 

[TheKracka]

Only made a tire circumference change and the speedometer seems pretty much spot on using Google maps on my phone for GPS. When the truck indicates 70mph the GPS indicates 69-70. At an indicated 45mph the GPS shows 44-45. So it seems like I might be going 1/4 - 1/2 of a mph slower than indicated.

Running 285/70/17 and used the value of 2526

 

[DocE3Gun]

Only made a tire circumference change and the speedometer seems pretty much spot on using Google maps on my phone for GPS. When the truck indicates 70mph the GPS indicates 69-70. At an indicated 45mph the GPS shows 44-45. So it seems like I might be going half to 3/4 of a mph slower than indicated.

Running 285/70/17 and used the value of 2526

My new tire size 265/70R18 appears to be nearly identical, so I’m going to try your number of 2526 first.

thank you

 

[TheKracka]

My new tire size 265/70R18 appears to be nearly identical, so I’m going to try your number of 2526 first.

thank you

You're welcome! Using the same formula, for your tire size I come up with 2519.

 

[PonyXpress]

New setup: 285/70/17 Falken Wildpeak A/T3W with Fuel Lethal 17/9 with the -12mm offset
changing the tire circumference to 2500 and it's right on the money at 70 mph.

 

[LRB45]

OK so I know I look like an idiot but why do I not see the 762-12-01 under bdycm module. I am using the latest beta of forscan so maybe that is why?

Yep I'm an idiot. I was not going into the AS BUILT module

 

[RangerRaptor]

New setup: 285/70/17 Falken Wildpeak A/T3W with Fuel Lethal 17/9 with the -12mm offset
changing the tire circumference to 2500 and it's right on the money at 70 mph.

is anyone reporting they can change the circumference with no error codes? If yes, what’s the secret?

 

[Igor]

Guys, need some help here.
OBD2 scanner should arrive today.
What is the verdict on the way of calibrating speedometer: BCM 726-12-01 code change or circumference change? Or it does not matter...

I went from stock 255/65R17 Bridgestone Duelers to 265/70R17 General Grabber ATX.
Is this a correct code I calculated? xxxx 0987 xxxx
Also where can I find circumference for my new tires?

Is it correct that 265/70R17 is kind of not "standard" size for Ranger and I will get U0422 code?

Thanks in advance.

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