Hi. We have had our new ACE 29D for about a month...
Any ideas what can cause this? Am I looking at a trip to a Ford service center?
Welcome to new RVs!

I have the same issue with a 2024 Freedom Traveler A32.
There is one possible fix that a dealer can flash and update the ABS system. There's something about tolerances, and the new code for ABS fixes that error. That's usually shows as an intermittent problem and the update fixes it (normally). You can probably find a dealer that will do the ABS update on the driveway, much more quickly.
If the ABS light and traction control light stay on, that's a different issue and is likely a physical problem with the ABS system, often the "tone ring" that helps the computer measure wheel speed. That requires more shop time, sadly.
For either error, you'll discover that the cruise control and the hill start assist also don't work if the errors are active.
In my case, the ABS software update (done at a Ford Truck center) didn't help. I'm waiting now to take in my motorhome, fortunately they don't have a year wait here. It will probably take a month to get it in, but at least they've already opened the ticket. I will take it physically into the shop once they are getting closer on the queue. I'm using a commercial truck repair center in Dallas. It's about a 60 mile drive for me, but the other Ford Authorized place only about 20 miles away had a wait of 3-4 months AND they required that it be brought to the lot and left (Those same people also disclaim any liability for the RV or contents while they have it!).
There is a Ford Motorhome Assistance Hotline at 800-444-3311. They may be able to help you find somewhere else to take your F53 Chassis. There is also a database at
https://fordcommercialvehiclecenter.com/ that allows you to search on vehicle types (Class A Motorhome). Even with the filter, you still have to check if the dealer has bays big enough for your RV. I did a lot of calling to discover that many don't service Class A RVs even though they are in the database. :/
Finally, you can open an NTSB safety problem report on the ABS if the updated software doesn't fix your problem. If you do, you will want to open two tickets, one with your actual motorhome make and model and one with the Ford F53 base chassis. If enough people report the issue, it may turn into a service bulletin or even a recall. It will start conversations, at least, between the NTSB, Ford, and motorhome manufacturers. I posted a separate message about this here:
https://www.thorforums.com/forums/f8/advance-trac-abs-error-35798.html
Good Luck!