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I have a 2023 Ford F550 Cab and Chassis we built into a brush truck. I installed super single Continental 235/80 20R tires (39.5" tall). To calibrate the speedometer we installed the Hypertech module. On hard corners and turns, I get a traction control error and an ABS error. The cruise is disabled, the hill descent quits working, and I get a message that the automatic brake system is disabled. I have the Ford Diagnostic Software, and from what I can tell, the problem is that the truck's roll stability system is seeing the wrong vehicle speed. Does anyone know how to change the tire size in the computer systems? Which module is the tire size stored in? How can I eliminate this problem?
Yeah rather than using a module to trick the speedometer, you're probably going to need to actually update the computer. ForScan software probably will do this. Dealer software can't. I think they are limited to 35" max. Try ForScan.
Thanks for your quick reply. According to the Ford Body Builder website, the 2023 Ford Super Duty has an encrypted CAN. In researching FORscan, I found a disclaimer for the 2023 model years. Does anyone know if Forscan works on the 2023 Ford Super Duty? Can you change the parameters?
I used forscan to change the tire size on my 24' XL. I have 37" tires and changes the tire value many times without any issues while I used trial and error to find the right setting based on GPS speed comparison. At least for my vehicle this was extremely easy and straight forward following the instructions I found on this site. Let us see pics of this beast!
Thanks for your quick reply. According to the Ford Body Builder website, the 2023 Ford Super Duty has an encrypted CAN. In researching FORscan, I found a disclaimer for the 2023 model years. Does anyone know if Forscan works on the 2023 Ford Super Duty? Can you change the parameters?
Yes it works. Make sure you have the latest version downloaded. When I first tried my 23 450 it wouldn't recognize. I had to contact ZooDad who had a contact at Forscan. He sent me a beta version to change my tire size.
Oddly enough I only had the unable to recognize this vehicle on the 450. My buddies Tremor worked just fine with the normal update they had available.
Hey @DuaneMartin, same issue here trying to run 335/80R20s. I was able to get Forscan to update tire size on my 2024 550 to 2800mm circumference, but anything higher throws check engine light. Were you a able to get any closer on your vehicle?
There is an aftermarket solution at https://bushel.biz/directdrive/tru-speed/. The installation is pretty technical; you might want to read the installation instructions.
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