Weird issue with rear hub motor

[Swell6]

I have a 36v system built around a KT-LCD5 display, KT36SVPR-LCD controller and rear hub motor which doesn't seem to have any model number visible.
I recently had an issue with an intermittent Hall sensor fault (03 error code) which I diagnosed as a bad trace on the PCB inside the motor to one of the sensors, fixed by fitting a jumper lead.
Its been working fine since that repair, until today. The motor started to stutter and made a sound which at first I thought was the disc brake rubbing, but then realised it was the motor. It cut out but was intermittently cutting back in with that strange sound. This was the case using both thumb throttle and pedal assist.

• I've removed the motor from the casing and am testing it with the axles mounted in the dropouts and the Julet connector connected
• visual check of all the connections and all look fine, no evidence of water ingress at all
• there's good continuity for all wires between the PCB and the 6 way plug on the controller
• all Hall sensor voltages are switching between about 5v and 0v
• the voltage on the white speed sensor connector is a constant voltage of about 5v
• when plugged in and powered up, the thumb throttle doesn't start the motor
• when I spin the motor by hand while activating the thumb throttle the motor starts and runs and I can vary the speed
• when I take my thumb off the throttle the motor stops but won't restart - unless I repeat the spinning by hand
• I notice that there is no speed registering on the display which I imagine there should be

So I really don't know what's going on here. I have searched but can't find any such issue reported elsewhere.
Any ideas?

 

[vfr400]

You can blow the mosfets in the controller if you try to run the motor like that. on'y use very low power settings until it's sorted.

The first place to check is all the motor connectors. Bullet connectors can look OK, but are not actually tight or properly engages. The 9-pin cinnector has to be all the way to the line, not just in tight.

The next place to check is the motor cable where it comes out of the axle.

After that, you need to measure the resistance of the mosfets between the red battery wire and each phase wire, then the black and each phase wire. Each group of three should be the same as each other and around 7K to 14K.

 

[Swell6]

You can blow the mosfets in the controller if you try to run the motor like that. on'y use very low power settings until it's sorted.

The first place to check is all the motor connectors. Bullet connectors can look OK, but are not actually tight or properly engages. The 9-pin cinnector has to be all the way to the line, not just in tight.

The next place to check is the motor cable where it comes out of the axle.

After that, you need to measure the resistance of the mosfets between the red battery wire and each phase wire, then the black and each phase wire. Each group of three should be the same as each other and around 7K to 14K.

I'm embarrassed...
I was just focused on the hall sensor wires and didn't even check the phase wires. One was disconnected and the motor works fine now its reconnected. I'm lucky not to have blown one of the mosfets...
Thanks for the reply!

 

[vfr400]

I'm embarrassed...
I was just focused on the hall sensor wires and didn't even check the phase wires. One was disconnected and the motor works fine now its reconnected. I'm lucky not to have blown one of the mosfets...
Thanks for the reply!

Another happy ending. I'll sleep better tonight.