All semi-truck related stuff got changed/updated in 0.31, so that mod needs to be updated to work with the new changes.
What mod is it from? It's possible that while you may have downloaded the most recent version of that mod, that doesn't guarantee that mod fixed the issue you are having. If we know more about it, we can better troubleshoot your issue ^^
I mean the creator of the MOD needs to update the mod. The reason its broken is because of the new GAME UPDATE, causing the MOD to be OUTDATED.
That's from the T-Series addon by AR162B & it no longer works unless you have the legacy files found here: https://www.beamng.com/threads/0-30-gavril-t-series-and-trailers.95616/
