Below is a list of the Function keys and their assignments applicable to this model. Plux 22 decoder, no speaker supplied as the model is pre fitted F0. Lights on/off F1. Sound on/off F2. Horn 1 - double F3. Horn 2 - double F4. Horn 3 - single F5. Buffer up F6. Coupling up F7. Flange squeal F8. Guards whistle F9. Carriage door slam F10. Wheel/track ‘groan’ F11. Uncouple F12. Air tick F13. Acceleration over ride F14. Switching mode F15. Aux 1 F16. Aux 2 F17. Aux 3 f18. Aux 4