P42 Idle Sound Question

[DutchRailnut]

Just speed adjustment when Electrical load on HEP changes. like heat or Ac kicking in, or Air compressor on locomotves

[amtrakhogger]

P42's have an auto-stop/start feature to save fuel.
Usually when the engine is shut-off then is about to start
that beep is a warning alarm to watch that the engine is
starting.
It is possible that the alarm also sounds when it loads up
to charge the main reservoir or batteries etc.

ah