Di2 help with faulty cable connection


I am having issues with my DI2, one day it stopped working all of a sudden the day after being charged, I made some investigations and I discovered it was a faulty connection of the cable coming from the battery with the junction box. In this case I was able to unwind a bit the battery cable and force it into the junction box in the sweat precise angle at which it would power everything up.

In order to do this I had to unwind a bit the cable from the rear break cable since it was spiraled on the rear brake cable. The overall look of this was a bit ugly.

For some reason today I could not resist and had the freaking BRILLIANT idea to rewind the cable to make it look nicer. As a result OBVIOUSLY it stopped working.

When I tried to go back I can no longer find the sweat angle at which the

As a result I think I am stranded with indoor training and ERG mode and the weather is still nice.

Please help! Will I have to change the whole Di2 junction box or just the battery cable? How difficult is it to change the battery cable? It is all routed internally and does not look so easy to do.

Any advice or suggestions are welcome.

There are usually two junction boxes in a Di2 bike - Junction A (near the handlebar) and Junction B (near the bottom bracket / battery).

If you suspect Junction B is at fault or one of its ports you can try plugging the cable into a different port. If things then magically come back to life you can replace the Junction B (they’re cheap - SM-JC41).
A Di2 Electric Wire (EW-SD50) isn’t that expensive either though.
GPLama has some nice videos on doing Di2 wiring (and tidying it up): https://www.youtube.com/c/ShaneMillerLama/search?query=di2

@GPLama how about a Di2 playlist? :wink: :wink:

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Great idea. Done!

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