Ultegra Di2 rear derailleur does not shift

[hmanner]

Hi,

I have a big issue with my rear Di2 derailleur. Here are the symptoms:

- battery is fully charged
- front derailleur works perfect
- crash mode reset works just fine (rear goes through all gears)
- when pressing the shifter button for the rear, the control unit light goes green
- often nothing happens in the rear during ordinary shifting, recently it has gone completely dead
- firmware upgraded last year, and diagnostics tool showed nothing

To me this indicates that:

- there is contact between the shifter and the control unit (because the light goes green), and
- there is contact between the control unit and the rear (because crash mode reset works)
- the derailleur works (at least kind of) because it goes through the gears on reset

Does anyone have any idea what is going on?

/Håkan

 

[ianrauk]

@Mr Haematocrit may be able to help.

 

[Mr Haematocrit]

Your derailleur needs to be sent back to Shimano.
It's crash protection circuit keeps triggering to protect it from further damage. When you reset it, you will make it work for a short period of time before the issue which triggers it happens.
Its usually a short circuit and only triggered in specific gears.

The diagnostic kit will be useless in this instance, seen it a couple of times on ultegra.

 

[hmanner]

Thanks for the reply!

Before recently (when it became much worse) it would typically fail a number of times, always when changing from any gear to a heavier gear. But then succeed on maybe the 10th click, without having to run a reset. At that time moving to lighter gears always worked fine. Now it fails almost all the time in both directions, but sometimes it manages to change a gear or two (without the reset). And I forgot to mention that I have a few times heard just a faint ticking sound from the rear. Does that still indicate a crash protection issue?

 

[Mr Haematocrit]

The faint ticking is likely your servo experiencing issues. It could be this triggering the crash protection repeatedly.. Only shimano can really tell you for certain.

 

[hmanner]

A local dealer ran the diagnostics and did some manual troubleshooting. Turned out to be the right shifter that was broken. Got a replacement for free (thank you shimano), and it looks like that did the trick.