Below is a list of the Function keys and their assignments applicable to this model. F0. Lights on/off F1. Sound on/off F2. Double tone horn 1 F3. Double tone horn 2 F4. Single horn F5. Notching up F6. Notcting down F7. Flange squeal F8. Spyrex air tick F9. Wheel/track ‘groan’ F10. Shunt mode/half speed F11. Acceleration/deceleration over-ride F12. Aux 1 F13. Aux 2 F14. Buffer up F15. Coupling up