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Di2 fix help

by Rendel Harris
Thu, Jan 07, 2021 18:40
10

Hi all,

I suspect I'm going to have to chuck the bike at the LBS for this, which I wouldn't mind, but they have such a backlog and limited capacity if anyone knows how to solve this I'd really appreciate it. 

I have 2014 Ultegra Di2 10 speed on my road bike, unfortunately I didn't realise that the rear derailleur wire had come away from its moorings on the chainstay and so putting it in the turbo managed to cut it in half - genius (I'm 52 tha knows...). I didn't notice this until I went back out on the road and found I couldn't change the rear gears, fortunately it was a flat London ride and the front mech was still working. So I've spliced the rear wire back together (or rather my DT teacher wife has) and lo and behold..the whole system's stopped working! The battery is fully charged (and was lasting at least 800kms between charges before so don't think that's the problem), I've cleaned all the contacts, unplugged everything and plugged it back in, I've tried the crash recovery holding down the button on the control box etc, but no joy. No lights of any sort on the control box. Clearly snapping the wire has upset the system in some way but I can't figure how, and if it has how did the front mech carry on but then packed up when the rear mech wire was rejoined?

If anyone has any suggestions as to what's wrong I'd be really grateful! Thanks. 

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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10 comments

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Rendel Harris | 4 years ago
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Many thanks for all the advice, definitely looks like one for the experts I fear, booking it in with the LBS this afternoon and fingers crossed - if I can get it repaired for under three figures I'm calling it a win!

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matthewn5 replied to Rendel Harris | 4 years ago
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How much did it cost in the end and what had gone wrong?

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Rendel Harris replied to matthewn5 | 4 years ago
1 like

matthewn5 wrote:

How much did it cost in the end and what had gone wrong?

Still don't know, my baby's been in the shop for three weeks! Turned out on top of the cut cable the battery mount was broken and corroded, advised by the shop that they could only use their own suppliers ("head office rules mate, sorry") who didn't stock such ancient bits so I had to order the part myself. Ordered from Germany with promised 48 hours delivery, then got an email saying only kidding. we'll have it for you February 23rd! So cancelled that and have found another supplier in the UK, waiting on delivery. Only £56 so although my dream of three figures has gone for a burton still might get out under £150...can't come soon enough, have ridden 1000 kms this month on Zwift using Mrs H's roadie (ok for Zwift, too small to feel safe on the road) and getting quite bored with it!

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Rendel Harris replied to matthewn5 | 3 years ago
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matthewn5 wrote:

How much did it cost in the end and what had gone wrong?

Just got it back, £73 plus £56 for the part I had to source myself. Not too unhappy with that, considering what I was braced for!

Many thanks for the suggestions and advice everyone.

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Westy | 4 years ago
1 like

Unfortunately, it sounds like your system has shorted - that probably didn't happen at the initial damage, more likely when repairing the old wire I'm afraid. The repair might have worked if the wire was disconnected completely before repairing, but generally speaking repairing Di2 wires is almost impossible and a big risk.

But its important to see whats damaged, and the only way to do that is to disconnect the damaged wire and run a full test using the PC linkage box. I've known Di2 problems where that is the only way to restore them. Depending on your setup, you might need an internal battery or junction box I'm afraid.

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AlsoSomniloquism | 4 years ago
1 like

I don't have Di2 but it could be this?

https://roadbikeaction.com/how-to-di2-crash-mode/Edit: just seen you have done this.

If it isn't then there is a chance that you did the wires the wrong way or did a short without realising it which at worse case might have blown a bit of the electrics on the board. 

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kil0ran | 4 years ago
1 like

Do you have the external or internal battery? Which handlebar junction box are you using?

As others have said, take the repaired wire out of the equation and see if front shifting then works.

If you have the internal seatpost battery and the newer handlebar junction (SM-EW90) you can plug everything in via the battery charger to your PC and run the eTube software to diagnose the issue. In my similar experience (when I yanked the rear mech wire out by accident because it hadn't been fully seated) I needed to do this to get it all working again. It's almost like you need to do a configuration reset on the battery (all the brains of Di2 is contained within the battery)

If you've got an external battery you'll need to rent/buy the PC linkage box - SM-PCE1 or SM-PCE02. They're expensive to buy but there are usually people renting them on eBay for around £30.

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hawkinspeter | 4 years ago
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First, replace the dodgy wire with a new one and see if that gets things working (depending on how easy it is to get to the junction box), but if that doesn't work, then it probably needs a new battery which isn't cheap.

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VeloUSA | 4 years ago
1 like

Have your LBS replace the wire from the junction box.

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Secret_squirrel | 4 years ago
1 like

The only thing I could suggest to try is to swap the joined wires over.

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