Possible causes:
Poor connection between battery and controller
The battery voltage is low or the battery is faulty or disconnected
Poor connection between motor wires and controller
Motor fuse blown
DOSS physically disconnected
Faulty motor and DOSS assembly
Possible solutions:
Ensure that the battery terminals are properly connected on both the controller and battery side
Measure the battery voltage – it should be no lower than 11V DC when placed under load.
Check for corrosive build-up around the battery terminals; if there is corrosion replace both the battery and battery terminals
Measure the onboard charger’s output voltage. It should be about 14V DC
Replace blown fuse. If it blows again, replace the controller
Disconnect the motor wires and reconnect, ensuring that the screws have been sufficiently tightened
Ensure that the DOSS cable is securely connected on both the controller and motor assembly side
Replace the battery
Replace faulty controller
Replace motor assembly