Bosch Purion – display not working

Help please! I went to go for a ride this morning but the Bosch Purion controller on my ebike wouldn’t switch on.

The battery is fully charged and I replaced the batteries in the control unit this morning too so as to rule that out. The battery will charge up when connected direct to the charger but not with the battery on the bike and the bike connected to the charger (well I assume the battery isn’t charging as usually the controller display would work and you’d get the visual cues that the battery was charging).

I used the bike last Wednesday and it performed faultlessly, finishing the ride with 2 bars/40% remaining.

The cable connecting the control looks fine, no outside indication of a split wire or chafing.

The motor, FWIW, is a Bosch Performance Line Gen 2 and is on a Trek Powerfly 9.7 (2017 – so well out of warranty).

I’ve done a quick Google search and not much is coming up so asking the masses.

Is there any damage to the speed sensor or its wiring/connections?

Can you disconnect the Purion fully and reconnect to rule out any loose connection issues?

Thanks but nope, the speed sensor and wiring/connections are all good.

Haven’t tried disconnecting the Purion display yet, need to get into the motor to do so and won’t have a chance to do so until later in the week.

If it’s just a new display then I can suck that up, but if it’s the motor…

Does your bike have a switch to power on the battery? If it does you should be able to start the bike regardless of whether or not the display is functional.. You can then test the motor by riding it.

Sadly not, Bosch Powertube battery and everything is controlled through the controller.

Does your bike have a switch to power on the battery? If it does you should be able to start the bike regardless of whether or not the display is functional.. You can then test the motor by riding it.

No, that’s not how the bosch system works, if the controller/display is broken the motor won’t do anything.

Switching the eBike system on/off
The following options are available for switching on the eBike system:
– Press the on/off button (1) of the on-board computer
with the eBike battery inserted.
– Press the on/off button of the eBike battery (see battery
operating instructions).
The drive is activated as soon as you start pedalling (except if you are using the push-assistance function or if the assist- ance level is set to OFF). The motor output depends on the settings of the assistance level on the on-board computer. As soon as you stop pedalling when in normal operation, or as soon as you have reached a speed of 25/45 km/h, the eBike drive switches off the assistance. The drive is automat- ically reactivated as soon you start pedalling again and the speed is below 25/45 km/h.
The following options are available for switching off the eBike system:
– Press the on/off button (1) of the on-board computer.
– Switch off the eBike battery using its on/off button (bi-
cycle manufacturer-specific solutions are possible when there is no access to the battery on/off button; see the bi- cycle manufacturer operating instructions).
The system shuts down after being switched off; this takes approximately three seconds. It cannot be switched back on until shutdown has been completed.
If the eBike is not moved for approx. 10 min and no button is pressed on the on-board computer, the eBike system switches off automatically in order to save energy.
Note: Always switch off the eBike system when you park the eBike.
Note: If the batteries of the on-board computer are empty, you can still switch on your eBike using the bike’s battery. It is, however, recommended that you replace the internal bat- teries as soon as possible in order to avoid damage.

The manual says you can switch it on with the battery/bike power button….

The manual says you can switch it on with the battery/bike power button….

That’s correct – if the controller/display isn’t knackered.

If the controller /display is knackered or not present then it doesn’t do anything

Edit :just read that excerpt above, it does imply the system should work without the display, but that’s not correct, or that excerpt is for a different system

Ah I see. OP needs to get to a dealer then by the sounds of it.

I had a cable solder joint fail on mine think it was about 40quid and I fitted it myself

Solder failing makes me think of the old Xbox red ring of death. Sorry if it’s a stupid question, but which part of the cable had failed? Controller end or motor end? The cable that I can currently get to feels like it’s all one length, no joins, but I could be wrong. (Haven’t removed the covers from the motor yet – still working out how to get the crank off!)

Isn’t there a button on the battery? There’s a hole in the frame on my whyte so you can see it

Nope, no button to switch the battery on directly. I’ve got a Bosch Powertube 500 FWIW.

https://www.batteries4pro.com/en/Mobility/electric-bike/bosch/3,15444-battery-bike-bosch-powertube-500-vertical-36v-500-wh-4047025782128.html

if you zoom into the second pic – that button there – sometimes covered with trim?

Nope, no button to switch the battery on directly. I’ve got a Bosch Powertube 500 FWIW.

I’ve just bought one of those batteries. It has a button. It’s low-key, but there all the same.

The batteries do have a button, but all it does is turn the battery on if the display isn’t connected/working.

Motor end, it was green and was fixable, although I did get a replacement cable and fitted it myself.
This was on a trek powerfly 9 lt 2017

Cranks are self extracting I believe, so big Allen key time AFAIK.

the reason im pointing it out is the exact same thing happened to me – took the battery out, put it back in and it was dead. i felt ill, then realised i must have pushed this button, so pressed it again and all was well with the world.

If it’s just a new display then I can suck that up, but if it’s the motor…

Go ask a dealer to plug the unit into the diagnostic computer (that port on the side of the unit, don’t plug a normal USB cable into it, you will need a new controller!) Worth the money to find out what code it throws out, they can also update the software if necessary too.

may sound like a stupid question, but how long did you leave it when trying to switch it back on? i know on my gen 4 bosch motor and system, if there is an interruption to power supply ie removing the battery without witching off at controller first or the battery self ejecting as your riding along (as it did with me on my rail), the system seems to go into some form of safe mode and will take a fair few sweaty anxious minutes to switch on again once the battery is refitted

porter_jamie and kayak23 – I stand corrected, it does appear there is a button there albeit hidden under trim and with a possible access hole on that trim. Haven’t had the chance to pull apart but will have a go later this evening – thank you!

Dirtyboy – thanks for the steer on the cranks and the solder/cable. Will update later once I’ve got the kids to bed and get some garage-time.

Feeling a bit more optimistic about this now, might not yield anything but appreciate the help so far and learning new stuff.

Got the cranks and motor covers off, everything looks fine in there. No broken, chafed, loose or stretched wires. It’s not spotlessly clean in there but nowhere near as bad as I was expecting – some dried dirt that blew out easily with the air line.

Have got the bike booked into my LeBS but they can’t take it until 23rd April so will continue to have a poke around until then.

Thanks for the advice everyone, it’s appreciated.

A very brief update on this. Just picked up my ebike from the LBS, they were unable to fix the fault. They plugged the controller into the diagnostic machine, the controller ‘recognised’ the USB link and was showing ‘USB’ on the controller screen. No fault readings, no updates, nothing obvious.

LBS stopped there because they’re not a Trek dealer and didn’t want to do anything to invalidate any warranty. The mechanic also admitted that whist he could run the diagnostics he wasn’t very familiar with the system and obviously a bit reticent. Can’t complain, guy was honest and didn’t charge me.

So, still no further forward. Tempted to buy a new controller and take a punt.

Did they plug in another controller?

Chances are a wire may have been pinched internally (I had this issue) & none of the diagnostics would pick it up.

Unfortunately not, they didn’t have another controller to try, hence my thinking of swapping it out.

Plan now is to get the controller off the bike, get into the controller to expose the contacts and start testing for continuity, hopefully make a start tonight.

o I took a punt on a new Bosch Kiox controller. This was £230 as opposed to the £100 for a new Purion. The Kiox is a much more pleasing display to use, colour display for a start and connects to the Bosch ebike app.

In terms of fitting the Kiox controller, it was a fiddly job that took a lot longer than it should, mainly because I was doing this for the first time so was considering everything instead of steaming in and removing bolts.

Nevertheless, I had to remove the motor to get to the plug for the controller. That wasn’t too difficult, four bolts, only one of which had tight access but by no means that difficult. Then it was on with removing the battery holder/brackets. This was four bolts top and bottom to remove each bracket from the frame. Annoyingly four of the bolts are security Torx bolts which require Torx bits with a hole in them. Makes sense but irritating because I only had Torx keys that would fit and that then meant access issues. Again, not insurmountable, just took more time to slacken/tighten each bolt.

Putting it all together was, as you’d imagine, much trickier because of a few issues. One, you have to get the cable routing spot on otherwise the motor won’t fit back in and two, getting the battery holder brackets spot on was some trial and error. It was easy to bolt them back on to the bike and to re-install the battery but unless they’re spot on you could have trouble with the lock mechanism for the battery meaning you wouldn’t be able to remove the key or even remove the battery itself. A little bit of patience and slackening off the top frame mounting bolts allows the freedom to get the mechanism working as intended.

Lastly, getting the motor bolted back on to the frame was an utter pain in the arse. Getting the top two bolts through the frame and motor mounts is simple enough but getting them to bite into the captive threads on the motor was the hard part. With hindsight, having the bike hanging from a workshop stand probably made that more difficult as you couldn’t really get a good purchase on the motor whilst driving just enough force on to the bolts for them to bite.

Unfortunately all of this was in vain as the new controller didn’t fix the problem. The new controller is working and it picks up a reading from the speedo on the rear wheel and also shows how much charge is in the Powertube battery but no assistance from the motor.

Ended up taking the bike to Energise Ebikes in Tunbridge Wells yesterday. They’ve just called me and told me it’s all fixed, ready to roll. The Kiox I bought is a little dated and needed updating with the latest software which seems to have fixed the issue of the motor not picking up. The bill for them sorting is £25. Must admit that I was expecting to have to buy a new motor so if my bike is now working as Bosch intends, I will be well happy.

Going back to my original problem, I can only assume this was down to a broken Purion controller. No idea what went wrong with it, could have been water ingress or a pinched/pulled wire. I’ve opened up the controller but there’s nothing obvious wrong.

👍 Nice update.