PAS Intermittent. Need Help

[j950]

I have a foldable e-bike, and I had to replace the PAS (Pedal Assist Sensor) disk as my old one broke. I bought a new unit of the same size from Amazon, which had 12 magnets. I removed 6 magnets to match my old unit. I had it installed at a bike repair shop. Now it works very intermittently. Before, I would see 2 bars of power assist on the screen at the controls level, but now I only see 1 bar, and most of the time, it comes and goes. What do I need to do to get it back to the way my bike used to work in power assist mode? I'm looking forward to any suggestions.

 

[EVELO]

Check the gap between the magnet disc and the sensor - if its intermittent it may be wobbly. Also double check the polarity of the magnets.

 

[j950]

Thank you Evelo for your suggestion. The gap between magnet and sensor is about 5mm and the disk is not wobbly. I am not sure on how to check the polarity of the magnets. I will watch videos on how to check polarity on youtube and see if it helps.

 

[Slaphappygamer]

To check the polarity, you should be able to use the old PAS magnet ring. Face the 2 rings toward each other. The rings should repel each other. If they attract, then the polarity is reversed.

I haven’t done this, but previous magnet experience tells me this would be a good way to verify poles.

 

[harryS]

5mm seems too much. I'd have to go look, but I think mine ar almost touching between sensor and disk.

 

[j950]

it was nearly touching when the bike repair shop installed it and was doing the same. I moved it 5 mm to see if it made any difference and it did not. Thanks for your suggestions.

 

[j950]

To check the polarity, you should be able to use the old PAS magnet ring. Face the 2 rings toward each other. The rings should repel each other. If they attract, then the polarity is reversed.

I haven’t done this, but previous magnet experience tells me this would be a good way to verify poles.

To check the polarity, you should be able to use the old PAS magnet ring. Face the 2 rings toward each other. The rings should repel each other. If they attract, then the polarity is reversed.

I haven’t done this, but previous magnet experience tells me this would be a good way to verify poles.

Thanks for your suggestion regarding polarity check.

 

[harryS]

Does it work if better you pedal backwards? That's one way of testing polarity, except they usually don't work at all when polarity is wrong.

I forgot one oddity that I've seen. Is the disk tight on the axle? I was having trouble with intermittent PAS on a bike and I even replaced the sensor, but kept the same disk. Turned out it was loose on the axle and would actually slip and not turn, because it was wobbling and would catch on the sensor. When I went to put some glue on the axle to hold it, the disk broke into pieces .
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[EVELO]

Sometimes these PAS sensors are just finicky out of the box - is it possible to get another one and swap it out? Unfortunately it's possible you got a dud.