Yamaha PW-ST Motor Jerky

[E-bobby]

Thanks for the further info. There's a good chance this issue is caused by an actual physical issue on the PCB. I suspect it could also be some kind of software limp mode that the motor is configured to go into if it reads the wrong speed. The reason I think that is because I've seen a load of reports of this exact issue from people who've tried to derestrict the motor by moving the magnet etc. If this is the case then replacing the PCB would fix the problem, as would replacing the whole motor, which seems to be the fix of choice for Haibike and the most common fix I've seen from Haibike dealers when still under warranty.

The most interesting post I've found is this one here:

https://www.emtbforums.com/threads/yamaha-pw-st-has-no-speed-or-power-flashing-function-display.33130/

It's the only post I've seen where replacing the speed sensor has fixed this exact issue. The extra step they took is to cycle the bike in limp mode for half an hour. I replaced my speed sensor the other day and only found this post today. I'm not long back in from a half an hour cycle on it in limp mode. No joy. Mine is still in limp mode...

I also found this video which explains exactly how to use the diagnostics menu on the Yamaha Sideswitch Display. So I've confirmed that my speed sensor is working and detecting revolutions of the magnet. I've also worked out that my bike has recently had an error 71, which "indicates a battery communication error, most often caused by a loose battery". I did have some issues like this the day before my bike went into this limp mode, though I never noticed the exact error at the time. Not sure if it's connected or not. Seems quite likely. I've had the occasional battery error issue in the past and just tightened up the appropriate bolts.

Hopefully some of that info is a help for you. I'll update you if I get any more.

Thanks mate that helps, how did you get to see the error code as I can’t seem to find any on mine? Is there some button configuration you need to do? Maybe my bike is in limp mode as in some earlier posts I posted my magnet from the sensor and it was miles off, it’s still off now as it rubs against the brake line but I might put it back to normal and pedal it a lot, I figured it wasn’t the magnet as I took the brake off and put an extended one on but I didn’t really pedal it to be honest. Let me know how u found the error code please! Thanks

 

[E-bobby]

Thanks for the further info. There's a good chance this issue is caused by an actual physical issue on the PCB. I suspect it could also be some kind of software limp mode that the motor is configured to go into if it reads the wrong speed. The reason I think that is because I've seen a load of reports of this exact issue from people who've tried to derestrict the motor by moving the magnet etc. If this is the case then replacing the PCB would fix the problem, as would replacing the whole motor, which seems to be the fix of choice for Haibike and the most common fix I've seen from Haibike dealers when still under warranty.

The most interesting post I've found is this one here:

https://www.emtbforums.com/threads/yamaha-pw-st-has-no-speed-or-power-flashing-function-display.33130/

It's the only post I've seen where replacing the speed sensor has fixed this exact issue. The extra step they took is to cycle the bike in limp mode for half an hour. I replaced my speed sensor the other day and only found this post today. I'm not long back in from a half an hour cycle on it in limp mode. No joy. Mine is still in limp mode...

I also found this video which explains exactly how to use the diagnostics menu on the Yamaha Sideswitch Display. So I've confirmed that my speed sensor is working and detecting revolutions of the magnet. I've also worked out that my bike has recently had an error 71, which "indicates a battery communication error, most often caused by a loose battery". I did have some issues like this the day before my bike went into this limp mode, though I never noticed the exact error at the time. Not sure if it's connected or not. Seems quite likely. I've had the occasional battery error issue in the past and just tightened up the appropriate bolts.

Hopefully some of that info is a help for you. I'll update you if I get any more.

Hmm so I’ve just did that diagnostics and everything is normal in it, no error codes, all voltage is fine mines 0.5 and the sensor is reading the revolutions? I do not know what to do now as it seems the pcb is ok? Or it would show in the codes wouldn’t it? I’ll email haibike and ask if it would show. Thanks

 

[soundwave]

haibike only make the frame but sometimes these things go wrong and show no error codes and even if it does it could be meaningless as a 500 error on my bike can be 83 different problems.

best to send it to ebike motor centre for a quote to fix it as dealers cant do much and will end up sending it to him anyway.

 

[E-bobby]

haibike only make the frame but sometimes these things go wrong and show no error codes and even if it does it could be meaningless as a 500 error on my bike can be 83 different problems.

best to send it to ebike motor centre for a quote to fix it as dealers cant do much and will end up sending it to him anyway.

Yeah fair enough I don’t wanna spend too much though if I could take it to a dealer and he tell me certainly what’s wrong with it that would be good, I did phone a local shop near me and he said pcb board but I don’t know if it’s actually that. Plus I can’t find any for sale only one is a straight one whereas mine is rounded/curves. All the bike shops I phoned is “we don’t do Yamaha”, “we need the new software box” or “too many bikes in we can’t take it in for now”. hopefully I find a shop that will be able to diagnose it. Cheers

 

[soundwave]

if you take it to a dealer they will charge you for a diagnostic report 30-50 quid and wont fit any parts anyway inside the motor.

if you send it in worst it will cost is postage to send it back but will tell you what needs replacing.

 

[saneagle]

If I were you, I'd send it in and ask them to do a full repair and bearing replacement. It'll probably cost around £400, but you'll get back a motor that's as good as new if not better. When you have these sort of motors, you have to expect to have to do repairs like that. Yours has probably had water in it, and once it starts to get in, the damage escalates until it's fixed.

 

[Vodsel]

Hmm so I’ve just did that diagnostics and everything is normal in it, no error codes, all voltage is fine mines 0.5 and the sensor is reading the revolutions? I do not know what to do now as it seems the pcb is ok? Or it would show in the codes wouldn’t it? I’ll email haibike and ask if it would show. Thanks

Interesting. I've had some battery issues with my Haibike for a while. In fact, I had some the day before mine went into limp mode. So I had reseated the battery. That might well be where the Error 71 came from. The display would turn off and I would lose assist. It's possible that I had an "error 71" again and that losing power somehow kicked my bike into limp mode. The display was off, and when I turned it back on again, I saw the flashing odometer, and I only had limp mode levels of assist.

The software that dealers use to run diagnostics on Yamaha motors has been uploaded online. I'm not sure if it would break any forum rules to link to any site with it on here. It's on EMTB forums though. I've not tried it as yet.

 

[E-bobby]

Interesting. I've had some battery issues with my Haibike for a while. In fact, I had some the day before mine went into limp mode. So I had reseated the battery. That might well be where the Error 71 came from. The display would turn off and I would lose assist. It's possible that I had an "error 71" again and that losing power somehow kicked my bike into limp mode. The display was off, and when I turned it back on again, I saw the flashing odometer, and I only had limp mode levels of assist.

The software that dealers use to run diagnostics on Yamaha motors has been uploaded online. I'm not sure if it would break any forum rules to link to any site with it on here. It's on EMTB forums though. I've not tried it as yet.

Is it like an app or like a physical thing you can buy? Like you can diagnose it yourself? Also I got an email back from Haibike. Basically telling me that a new motor is probably required (see pic). Hope this helps

 

[Vodsel]

Is it like an app or like a physical thing you can buy? Like you can diagnose it yourself? Also I got an email back from Haibike. Basically telling me that a new motor is probably required (see pic). Hope this helps

Yeah that's pretty much the same response I got from Haibike about the same problem. Which is fine if the bike is still in warranty but as ours aren't and the problem could possibly be fixed by riding the bike for 30 minutes it seems a bit like "when your only tool is a hammer, everything looks like a nail".

Sure a new ebike motor will fix pretty much all ebike motor related problems but in some cases so will other things that don't cost £795...

 

[E-bobby]

Yeah that's pretty much the same response I got from Haibike about the same problem. Which is fine if the bike is still in warranty but as ours aren't and the problem could possibly be fixed by riding the bike for 30 minutes it seems a bit like "when your only tool is a hammer, everything looks like a nail".

Sure a new ebike motor will fix pretty much all ebike motor related problems but in some cases so will other things that don't cost £795...

Yea I don’t really want to pedal a 25kg bike for 30 mins with the chance of nothing happening, I’m sure a hard reset or something would do the same as that and it’s done nothing. Do you know if it’s a regular old usb cable I need or a special one to connect?

 

[Vodsel]

Yea I don’t really want to pedal a 25kg bike for 30 mins with the chance of nothing happening, I’m sure a hard reset or something would do the same as that and it’s done nothing. Do you know if it’s a regular old usb cable I need or a special one to connect?

I'm going to give the 30+ minute cycle thing another go soon when the wind calms down a bit. Probably over the weekend. I'll let you know if it fixes it or not.

It should just be a normal USB cable. USB micro I think.

 

[E-bobby]

I'm going to give the 30+ minute cycle thing another go soon when the wind calms down a bit. Probably over the weekend. I'll let you know if it fixes it or not.

It should just be a normal USB cable. USB micro I think.

Ok mate let me know how it goes! I’ll try that diagnostic on Sunday and I’ll let you know how that goes. Hopefully we can find a fix

 

[E-bobby]

Hi all! I did the diagnostic test today and managed to extract some information. Basically there is a code 36. Abnormal voltage. The battery is at 9 volts when it happened which I’m not sure is correct. I think it’s supposed to be 36-42 and my torque sensor was 0.1 at the time. Currently on the test it was 0.5. Everything passed the tests I did except the sensor. It wouldn’t move from 0.5v. I tried putting pressure on the pedals but that only made the motor load go up. I tried pedalling, nothing. So it points me in 2 directions, battery connections or torque sensor. Anyone advise anything on this?

 

[Nealh]

9v ?
BMS fault ?