Below is a list of the Function keys and their assignments applicable to this model. F0. Lights on /off F1. Sound on/off F2. Horn 1, two tone F3. Horn 2, two tone F4. Horn 3, single tone F5. Buffer up F6. Coupling up F7. Flange squeal F8. Sound of sanding the wheels for grip on acceleration F9. Shunting mode, Press once the loco goes half speed, press it again and you are back to normal control. F10. Acceleration/Deceleration speed over ride. F11. Aux1 F12. Aux2