Controller Failure and Malfunction
Controllers can fail for several reasons, the most common are moisture, overload, shock and modification .
 The main reason controllers fail is moisture . Most controllers are ventilated for heat dispersion , unfortunently this ventilation is an open invitation to water through condensation or direct contact . Several scooter manufactures place the controller in the battery pan, this is an example of terribly negligent design because moisture is bound contact the controller.
 Overload occurs when to much current passes through the system resulting in heat damage. This problem is usually due to poor electrical design and or controller construction. Electrical design problems can be extremely simple to diagnose EX .use a smaller main fuse, replace bad motor or very complicated, like hunting a ghost EX. EMF distortion issues. A good controller will protect itself from overload, it may refuse user commands but the controller will survive.
 Scooters rarely use a common ground design for safety and electrical noise minimization, but even small distortions can cause controller malfunction or even damage. The only way to keep these distortions to a minimum is by bundling (keep the wires together) so the emission from one wire is absorbed by another and through controller centralization (placement of the controller in the middle of the field) although this is actually impossible due to the fact the main EMF generating systems are the motor, and the controller itself. So the perfect location for a controller would be on the motor but this would cause a heat issue so keep the motor system and battery system wires close together while keeping wires as short as possible and place the controller in a location close to the motor and away from moisture (good luck).
 Shock damage is caused by the user and occurs when the charger is plugged into the AC current before it is plugged into the scooter's charging port causing the controller to recognize the charger several times while sending arcs of static and blasts of DC current into the controller possibly causing controller syntax jumping , when this occurs anything the controller is capable of may happen and even result in SCR damage causing the system to run at full power when the charger is de-energized or removed .
 Modification, these problems actually fall in in the poor construction category . Custom modifications can cause controller failure . Never use a ground other than the battery ( no common frame grounding ), avoid emissions and overloading any controller circuit . Never supercharge , don't pull power from the lock circuit . Use proper size wires and fuse protection . Don't bypass the charging or break (not break light ) circuit . Avoid generation or reverse generation , this occurs when the motor turns at high speed without power , rolling backwards at high speed or rolling forward at high speed while not under power with freewheel malfunction , the motor acts as a generator sending current back to the controller .

Happy Scootering
Test your hall effect throttle