• The Problem Is Most Likely The Speed Controller

In our shop around 99% of the time when the motor runs constantly it is due to a defective speed controller. However, on occasion, it may also be caused by a defective throttle or a short circuit in the throttle cable or connector.

  • Test The Throttle And Speed Controller

To test whether the problem is the throttle or the speed controller disconnect the throttle from the speed controller. If the motor stops running then the throttle is defective. If the motor still runs constantly then the speed controller is defective.

  • The Reason Why Motors Run Constantly

Electric scooter speed controllers use MOSFET transistors to control the motor's speed. When these type of transistors burn out they lock the power into the on position causing the motor to run at full speed continuously.

  • Speed Controller Replacement

Direct fitting "plug-and-play" speed controllers are often not available for older model and off-brand Chinese-made electric scooters and bicycles. Substituting a new speed controller with the same Voltage rating and an equal or slightly higher Wattage rating than the old speed controller that it is replacing or motor that it is being used with is the only way to repair a scooter that does not have a plug-and-play speed controller available for it. For more information and tips about speed controller replacement visit our Speed Controller Replacement Help area.