First time repairing my e-bike - Cube MtB with Yose Power conversion kit

[geszler]

Hey all,

I got my first E-Bike about 2 years ago. A Cube MtB with a Yosepower conversion kit that I did not do myself but got from e-bay pre-owned for cheap.

Against all odds it went like a charm for the last two years and all I had to do was the normal bike maintenance. But alas the time has come! Yesterday it worked fine, this morning it didn't.

The Battery is fine and well. The display works and does what its supposed to. But when I start pedalling the motor does not start turning/supporting.

When I'm driving the display does show the correct speed but does not show how strong the motor is supposed to support, which makes me hope it is only the PAS sensor. But I have not the slightest idea if that's actually true, nor how I could confirm this guess

I unplugged all the connections I found. No water or corrosion in any of them.

So how would all of you start identifying the problem?

Is there any beginners repair guide for e-bikes that you can recommend?

Cheers in advance

 

[Annieolnie]

Could you tell us more about your ebike? How many volts is your battery, what size motor and most importantly, where is it? Is there a light on your pas sensor and is it working. You are in the EU, so I should ask if you have a throttle? Tell us everything you can to help with your puzzle and we will see what we can figure out.

 

[geszler]

Hi Annie.
Battery is 36v
Its this motor with 250W rear mounted
Its this sensor
No throttle
Thankyou for your help

 

[Annieolnie]

Hi Annie.
Battery is 36v
Its this motor with 250W rear mounted
Its this sensor
No throttle
Thank youfor your help

So, is your motor dead? If you are off the bike and you lift the rear wheel and turn the cranks in different pedal assist modes, does the motor kick in? Can you also tell me what display you have? Will it show error codes?

 

[geszler]

The display is a YP C500 which is able to show error codes but does not.
Reading the user manual for the first time though I discovered that if I press "-" for long it enganges a "walking" mode - having the motor run on 5km/h.
And it works! The motor does turn in "walking mode". It does not kick in when I turn the cranks though.

 

[Annieolnie]

Is there a little red diode on, on your pas sensor? If you have the light then you can try moving the sensor closer to its ring, if it is that type.

 

[geszler]

No it does not have a light and i can not move it around. https://www.yosepower.co.uk/collections/e-bike-accessories/products/pedal-pas-sensor-for-left-side

 

[Annieolnie]

OK, it looks like the all in one type without a ring. If you have a multimeter you could test the bike-side part of the plug to make sure it is getting power and it's not the controller or you can just try replacing it. I'm not sure this is the problem but it is a reasonable place to start. You will need to pull your crank arms, which is much easier than people think. You will need an 8mm allen wrench, a crank puller and a wrench to put on the crank puller. There are numerous YouTube videos on how to do it. You can watch the videos and decide if you want to give it a try. Your pas sensor will just slide off once the crank arm is gone. There are videos for that too if you need them.

 

[geszler]

Thank you for your help. I got a friend around and we switched our PAS sensors which ended up in his bike not working anymore and mine working.
Problem found
Thank you Annie for your help!

 

[Annieolnie]

Thank you for your help. I got a friend around and we switched our PAS sensors which ended up in his bike not working anymore and mine working.
Problem found
Thank you Annie for your help!

Well, OK. Good to know I was headed in the right direction.

 

[alihyder]

Sounds like your e-bike’s motor not kicking in could be a simple issue with the pedal assist sensor (PAS). Since your display and battery are working fine, and it still shows speed while riding, there's a good chance the motor just isn’t getting the signal to start helping. The sensor usually sits near the pedals; it’s a little ring with magnets and a small sensor next to it. If that’s moved out of place or got dirty, the motor won’t respond. Try checking if it’s lined up properly (just a few millimeters apart), give it a quick clean, and unplug/replug the cable to make sure everything’s connected tight. If your bike has a throttle and that still works, then it’s almost definitely the PAS.