ESU Sound Decoder GWR-61xx Priarie - ESU sound decoder and speaker

Below is a list of the Function keys and their assignments applicable to this model.
F1. Sound on/off
F2. Whistle (long) – continues until F2 is pressed again
F3. Whistle (short)
F4. Buffering up
F5. Coupling up
F6. Injectors
F7. Drain cocks
F8. Safety valve
F9. Guards whistle
F10. Carriage door ‘slam’
F11. Sleeper/track ‘groan’
F12. Shunting mode. Press once the loco goes slowly, press it again and you are back to normal control.
F13. Acceleration/Deceleration over ride. Press once to over ride, press again to return to preset settings.
F14. Aux 1
F15. Aux 2

Image Source:

Wikipedia https://en.wikipedia.org/wiki/GWR_4575_Class