How is the device connected to the dynamo?
Please find out which of the two cables coming from the dynamo is connected to the centre lamp contact. Once the correct cable has been determined, it has to be separated within close proximity to the M172N. Take the end coming from the dynamo and connect it to the “Dynamo” connection on the M172N. The other cable end (going to the two lamps) is connected to the “Light” connection on the M172N.
The “Frame” connection is connected with the wire that runs from the outer lamp contact to the dynamo.