The steering axles are now automatically locked when the AutoDrive drives the trailer backwards.
I made a little script that enables the steering axles on trailers to be locked and unlocked.
You can find a small demo vid here below.
Think much more is never to say.
Controller (X-Box): LB + control pad right.
File :20 KB / ZIP
Download FS19 – Lock Steering Axle V1.1 - modsbase.com