Shimano SC-E8000 computer / controller / display goes off with light connected to it.


New member
Local time
4:51 PM
Jul 26, 2020
I probably saw/read somewhere that shimano does not recomend anymore since the new 8000 model to attach the light to this computer and instead they made special connectors on the engine itself but I had to try.
I had anyway an extra cable that I could use/cut and fit to a pretty strong light that I bought cheap from ebay(60000Lm 16x XM-T6 LED 3Mode Cycling Bicycle Light) I think it's rated 8.4 Volt compared to 6V officially shimano blessed models.
So it looks like it's working at least on one side but then the mode-trigger/shifter stops working(does not switch anymore from/to eco/trail/boost) and that even if the light is not yet turned on. I mean, I see the green led(power status) on the light back button but it's not yet on. It does turn on/off and I can use it no problem there. The computer it self still works(switches to different odo/dst/cadence/etc. data), it's just the trigger that can't seem to work.
Is is perhaps digital signaling?? and I am jamming that signal with the light ? Can someone please shed some light on this? Can I fix it with some circuit filter perhaps?
Anyway another strange thing is that if I connect the light before powering on the battery the computer stays and remains off and only starts if I reconnect(remove and reattach) the light back to it. It can't be something like a short circuit is it ? I know it also sucks a lot of amps when it's on but at this stage it's not even turned on.
Has someone experienced this, opinions ?
Thanks in advance.
This is the main problem.

First, the claimed output is far from reality. In perfect conditions, 1 XM-L T6 can produce about 1000 lumens.

And to give this output it needs about 7 W, again in perfect conditions.

So 16 LED would drain about 100 W!

These kind of lights outputs on ebike are more in the 10 W range.

Apart from this, does the light work connected to an external battery pack?
Yes it works! And very well I would add. Even on the bike. Works, but as I said before it cuts the communication between the mode trigger/switch and computer. That even before turning it on.
So my question remains, is it a digital signalling going on there?
I guess I need to get my head into this and do some measurements.
I don't think too many users here have the Shimano Steps. In fact, not too many own Ebikes. I would check out another website.
On the light side there is "nothing". But the computer can detect if some abnormal current is drained and I think this light don't have a simple on/off power switch so it may never be totally off.