Sorry you haven't had any replies to this. I have the same bike but I have only had this problem with the motor dragging a couple of times and always at low speed. Once when climing and recently when pulling away. The last time it happened I also noticed the pink flashing light, but I turned it...
You can download the blue paper from the Vibe product page on the Orbea website. The task of adding a light to the existing wiring looks like it will be quite awkward and time consuming. In the blue paper you need to look at pages 69-73.
Hope this helps.