There is no AC4400CW in Train Simulator, you need to report to the TSW2 forum here:https://forums.dovetailgames.com/forums/technical-reports.80/
If you are using Searchlight Simulations CP AC4400CW Golden Beaver read the manual. In certain cases sounds can disappear.This may be normal.
Is there a fix for this horn issue?? Only seems to not work when it is outside the cab, being inside the cab, the horn works fine
I would suggest to reinstall this item. Use the uninstall located in your Railworks folder. Then use the original install .exe sent plus any updates (there has been at least one). You should have saved them. If not then request another download. The website is currently down as of this date. My copy works properly, yours may have been corrupted somehow.
Because someone prior to OldAlaskaGuy necroposted (not in a bad way in this case, I assume made a search and was thrown this thread as a result) and OAG probably never noticed the date gap prior to that. Your post is seemingly quite aggressive, I'm not entirely sure why it seems to bother you that someone quoted you from 4 years ago but I thought I'd chip in with the possible cause to set you at ease.