I have ben having problems at startup on my road bike equipped with a #902 motor system. On power-up I get a two-beep error message indicating a Hall-sensor problem. On application of throttle I get a short shudder of motor power, indicating a lack of signals from the Hall circuit. Removing the Hall circuit connection to the controller yields the same shudder on startup, indicating a sensor-less start.
Initially I tested the signals from the Hall circuit and found one slightly weaker than the other two, so I took the motor apart and replaced the weak sensor. On reassembly, I got the same result, sensor-less startup.
To determine if the problem may have been with the controller, I connected the motor wheels from two other bikes (I have four bikes with 902 systems) and got normal results...no error signal and smooth startup. And I connected the road bike motor wheel to two other controllers and throttles and got the same error signals and jerky startup as before.
So I concluded that the problem must be with the Hall sensor circuit in the motor. I took the motor apart again and replaced all three Hall sensors and all the wiring of the Hall circuit (except for the wires in the main external cable to the controller), and checked everything carefully for continuity and short circuitry. When reassembled with the original controller, I still got the error beeps and jerky sensor-less start. I tried the motor wheel on the other two spare controllers, with the same results.
Just on the unlikely chance that I got the Hall sensors switched into the wrong order of positions when I installed them in the motor, I tried switching the signal leads from the sensors to the controller, with no difference in the results.
So obviously there appears to be something wrong with the motor, other that a Hall sensor problem. But what??
What else should I try, other than replace the motor?
And what are the long-term consequences of just putting up with the startup shudder, and just operate with sensor-less starting all the time??
Roy
