Advice needed - Pedal assist doesn't work (but Walk assist works)

[Demid Tishin]

Hi folks, can anyone advise on a technical issue?

I have a pedal-assist Amladcykler trike with a brushless rear hub motor (36 V), which now ran approx. 4,500 km.
A couple of days ago I had to take the back wheel off to fix a puncture.
Yesterday the bike started to act weird.
The moment I start pushing the pedals, the display immediately jumps from showing the speed of 0 kmh to the speed of 80 kmh (please see attached picture) and assist doesn't kick in. When I ride, it constantly shows "80 kmh" and the motor doesn't work. Strangely, the "walk assist" function works correctly (steady movement on motor power only at approx. 5 kmh when long-pressing the "up" button on the display), but the display still shows 80 kmh.
- The wheel diameter is set up correctly (26'')
- I checked and dried the connector pins and connector socket where the back wheel connects to the controller.
- I checked the magnetic plate on the crank wheel and the sensor - they look OK to me, but I'm no expert. The red LED on the sensor flashes when I turn the crank forward.
- There is some damage to the rear wheel cable at the point where it enters the wheel but it has been like that for a long time. I may have disturbed it when reinstalling the back wheel.

Questions:
- What is most likely causing the problem? How do I narrow down the culprit?
- Could resetting the bike to factory settings help? If yes, how do I do that? I tried pressing various button combinations especially in the first two seconds after switching the LCD on, but to no effect. Pressing the "set" and "down" buttons as recommended in the troubleshooting guide (screenshot attached) doesn't show any error codes on the screen.

I contacted the seller but they simply told me to go through the guide and if the issue remains, buy a new sensor and a new LCD. But how do I know this will fix the problem? We really need this fixed as we use the trike every day to get our three kids around town.

Thanks a lot for any leads!

 

[amberwolf]

there's a speed sensor that's in or on the motor wheel. that is probably disconnected now, most likely from this:

- There is some damage to the rear wheel cable at the point where it enters the wheel but it has been like that for a long time. I may have disturbed it when reinstalling the back wheel.

most likely there is at least one wire that is now broken inside that bundle. alternately, there could be several wires with broken insulation, and some of them could be shorting together, or shorting to the axle.

the "simplest" way to fix the problem is to open the motor and pull the cable into the motor enough to repair those wires, but if that isn't an option, you can attempt to repair them as they are, at the axle exit point, if there is enough cable there to be able to do this.

note that if the problem is shorted wires, it is possible that reinsulating them won't fix it, if a phase wire shorted to the speed sensor wire, as that could ahve destroyed the sensor (which could be replaced, or potentially use an external) and/or the receiver for it inside the controller (which can't be fixed).


the reason assist isn't working is the systme is probably limited so it can't assist you beyond a certain speed, which is almost certainly less than 80kmh. since the system thinks it's going faster than that, it won't allow assist.

so it almost certainly has nothing to do with the lcd or the pedal sensor, and is just the wiring at the wheel (unless the wiring fault has damaged other parts).


a side note: whenever wires are damaged, on any device or system, it's not a good idea to keep using it without repairing those. depending on what the wires are, and what the device is, it's possible for anything from a simple failure to a fire to occur.

 

[Demid Tishin]

Thanks very much @amberwolf, this is exactly why the seller's reply looked odd to me, the support guy never even mentioned the speed sensor... I'll try to repair the wires and let you know how it progresses.