The switch was the on/off on my Haibike (it also had all the functions including PAS incorporated). The nearest Haibike dealer according to their site was in Iceland since they had left the US (AFAICT) at the time. Fortunately, my local Yamaha dealer had a similar unit. I used the Bafang DIY conversion for almost seven years in pretty severe off road conditions, then my son wanted it, and he rides it almost daily. It has never needed maintenance nor ever failed. It's easy to call me a liar online, something I doubt you'd do to my face.
