PMike

I was given a really nice steel frame bike. Over the last 6 months or so, I've been saving and buying all the parts (new from various reputable vendors) to build it up using external 6870 Di2 for the group set. Now that it is assembled, nothing will shift.

I have built a handful of bikes with mechanical group sets. This is my first time working with Di2. It is likely I am missing something.

Everything is assembled as per the Shimano manual. The 2 shifters cables are connected to the A Junction (3 port) with another cable going to the rear junction. The rear junction has 4 ports filled with the RD cable, FD cable, battery cable, and cable to the A junction. When I insert the battery, the green light on the A Junction lights up as expected. However, the derailleurs don't move when tapping the shifter buttons. Nothing. I can go through the a junction options as the instructions dictate (blinking lights, no blinking light, solid lights for the different modes) for the fall protection thing and still the derailleur don't move.

Anyone have this problem? If power is getting to the A Junction, both junctions must be fine. Would a bad wire make the A junction work but nothing shift? Bad wire? On/off switch somewhere I'm missing! ;-)

Again, I don't know much about Di2. Just what I've read online. It seems like it should work. I was going to take it to a shop but figured I'd ask here first.

Thanks for any help!

Cyclist0108

I'm no expert, but two suggestions:

1. Use the software diagnostic (assuming you have the computer interface):



2. Crash reset: Art's Cyclery Blog » Ask a Mechanic: Shimano Di2 Crash Recovery Mode

PMike

Cyclist0108

That thing in the picture came with mine. It is both the charging device and computer interface. Mine was set up by my frame-builder, but I am fairly sure you need to use the software to get everything recognized and integrated.

PMike

TimothyH

This is solid logic and standard troubleshooting.

It is possible that you have two bad ports on junction B and the derailleurs happen to be plugged into those ports, or the same issue with junction A and the shifters. Highly unlikely. .

To validate, Di2 doesn't care where anything is plugged in. You could remove everything, lay it out on a table and play musical ports as a test. Based on your description however, this sounds systemic. My guess is firmware.

Get the latest E-Tube software from https://e-tubeproject.shimano.com, connect the system to your PC using the SRM-BCR2 and see what it says.


-Tim-

PMike

TimothyH

Apparently my reading skills have declined over the years. I did not see where you wrote that it was external and assumed you had an internal system.

I don't know much about the external battery system. I don't know if the SM-BCR2 with E-Tube will recognize a system with an external battery.

Let me know if you are near Atlanta. I'd be happy to assist and we could find out.


-Tim-

Cyclist0108

Yes. Sorry. I just assumed they all worked the same way. That thing in the pic connects to the junction box via a port with a little rubber flap over it.

PMike

PMike

sch

Are you absolutely sure you have all the cables firmly seated in their connectors? It takes a fair push to fully seat the plugs.
There is an initial felt 'pop' that seems to indicate seating but there should be a second more solid 'thunk' that indicates the
cable plug is fully seated (these are felt, not heard). The tool helps a little in limited access scenarios like the 2d and 3d cables
on that pictured A port above.

Should be easy to move the RD/FD/Batt/A connector cables around the B connector to validate the competency of all the
ports on the B connector. As to the software, be cautious about allowing any firmware updates to be done, they tend
to be irreversible. No update will be needed to get your setup working.

PMike

I am pretty sure all cables are seated correctly. I've done it a couple times now and have a pretty good feel for that click/thud/action.

Your second paragraph is thought provoking. If I took out the FD from the equation (removed the right shifter cable from the a junction and the FD cable from the rear junction) and assuming all of those cables were good, will things work? Does every port have to be filled? This would be the scenario with a 1X11 system. I could swap cables around this way and there would be less variables.

Second, say more about the firmware thing. When I plug it in, will it automatically update things? I did buy the shifters, RD, and FD from different places. Depending on how long they sat in a warehouse, is there a chance they came with different firmware versions? Would that upgrade then fix my problem? I don't know the answer to any of these things, I'm just asking.

Thanks so much for your thoughts.

flanso 

There is a junction box in my bike's down tube above the bottom bracket and, as I recall, the wiring is rather crowded in there especially when the crank is installed. That would be the first place I would check connections. The E-Tube software includes a system check that identifies each component that is recognized. That diagnosis would probably identify your problem. Borrowing the interface might be your easiest solution.

squirtdad

Dumb question......OP notes they assembled group over time vs buying it all together. Could there be an incompatibility? maybe one part is not 6870....or has firmware version difference?

sch

Can't give any advice as to firmware problems, but a google on Di2 firmware problems will give a lot of posts and info about what is
useful and what might be dangerous. Firmware updating tends to be automatic, hence my proviso. OTOH there are scenarios
where the shifters might not get their commands through the A junction, which is where the firmware mostly resides, at least
until the 2d gen internal battery came out. Your system is simpler and the basic comm protocol Shimano uses for the
brifters to tell the RD/FD to move hasn't changed since 6770. As others have said, the B junction ports are all equal, so simple
trouble shooting there with swapping cables around should tell you if all ports have continuity. There is no intelligence (firmware) in the
B junction, it is just a dumb connector. Right now you know that the port the battery connects to and the port that the A junction to
B junction cable is plugged into work as the A junction is getting power. It is unlikely the B junction is faulty but it is easy to check
by swapping cables around.

This article suggests that prior posters suggestions about different firmware levels in the RD/FD from the A junction/brifters can be a
cause of comm failure. https://cyclingindustry.news/trainin...customisation/
It is fixable, but might be best left to a shop Di2 guru.

PMike

I finally was able to borrow the computer connection piece and get to a Windows computer (all of computers are Macs). Everything was immediately recognized and the A junction needed to update the firmware. I updated. Then I had to update the A junction again. Then it said that the brifters and a junction needed updated. I did that. Then it said it was all set. I hit the buttons on the brifters and...it all worked!!!

Thanks so much for all of the support above. All of my hardware was fine. My assembling and building techniques were fine. It just needed plugged into a computer and the firmware needed an update (or multiple). Again, thank you to all who responded and helped me think through this!