Musical horn requires holding the button

[marcriera]

On Final, on trains with a musical horn, pressing and releasing the horn button plays the whole length of the musical horn. On the patched Plug and Play, however, releasing the button stops the musical horn, so it's necessary to hold the button to hear it completely. Probably due to a minor code change when these horns were replaced with a standard one.

This is noticeable, for example, on the Chūō line, diagram 10.

[GMMan]

This might just be how the implementation on the PnP works. They seem to have replaced the original playback function with one designed for the new engine, and with them explicitly not allowing the horn, the behavior is not implemented.