This is how to turn the lights on and off on a Bosch powered Xtracycle cycle with a Purion display. The Purion display is located by the left handle bar grip and it is used to activate the Herrmans front and rear lights which come included on Bosch powered Xtracycles.
To switch on the front and rear lights, medium press the + button on the top left of the display (circled in orange). To switch off the bike lights, long press the + button. The lighting symbol (circled in blue) will display when the light is on.