As the ProKit 902 is a geared minimotor, I'm surprised it works at all if the hall sensors have failed. The minimotors don't usually work in sensorless mode, because the freewheel device
(unidirectional clutch) inside the hub prevents the motor from being turned by the wheel.
In sensorless mode, the motor has to be turning before the controller can detect the position of the poles to start assisting, but this is not a problem for the direct drive ProKit 901 or Magic Pies.
I would suggest a close inspection of the terminals on the battery plug and battery to check for a decent connection, it may just be that the vibration of the bikes movement is enabling the poor contacts to make a reasonable connection.
Check to see if the battery indicator lights on the throttle go out when the fault is there.
If it's not that, check the voltage reading between the
Z/0V connection and the
T2 connection on the controller, this should vary between ~0.8V and ~4.5V when the throttle is operated.
If however, it's a ProKit 901
(not a minimotor), I would say it's most likely to be a hall sensor problem too.
Take a look at
this post and
this video for more details on testing the operation of the hall sensors.
Please note that the minimotors need to be turned
very slowly in a
reverse direction when checking for variation of the hall sensors' signal voltage.
There's also some more useful information
here.
Let us know what you find.
Alan
