How do I connect or disconnect Di2 electric wires?

I recommend you use Shimano’s TL-EW02 cable plug tool to connect and disconnect your 10-speed and 11-speed components. For 12-speed EW-SD300 wires, use the TL-EW300 tool.

These tools make it so much easier to connect things properly, especially 12-speed wire.

Note that when plugging in a Di2 wire you should feel and hear a click when connecting your wires.