LCD display problem

[johnebike]

My wife's Cyclotricity conversion kit front hub motor system has developed a problem in displaying the road speed/distance on the LCD display.
The data only shows when the motor is under power but the speed reading fluctuates wildly and when the motor is on power level 0 it is not displayed at all.
The system has an external magnet speed sensor and it does seem to be correctly positioned .
I hope that someone can advise what I should look at next ?

 

[Nealh]

If all other lcd functions are working correctly then suspect the sensor may be faulty, also check the wiring for damage and the connection to make sure all pins are a good fit. If you are able to open the sensor then disconnect it and try a continuity check on the wiring.

 

[johnebike]

If all other lcd functions are working correctly then suspect the sensor may be faulty, also check the wiring for damage and the connection to make sure all pins are a good fit. If you are able to open the sensor then disconnect it and try a continuity check on the wiring.

 

[johnebike]

Thanks Nealh for your suggestion
I removed the speed sensor and opened it. It all looked neat with connections embedded in a sealant.
Since looking at this I have studied the malfunction more closely and have noticed the following

When the power is off there is no speed signal
When the power is on there is only a speed signal when pedalling.
When the power is applied via the thumb throttle there is a speed signal even when not pedalling !

I hope that this info can help indicate the source of the problem
Thanks again for any help

 

[Deleted member 4366]

Your LCD/controller are using a motor hall sensor for the speed signal. You need to test whether your speed sensor is working. With it powered, check between the signal (white?) wire and ground. You should see it pulse once at 5v for each rotation of the wheel.