Dc motor controller in use may encounter the light did not turn, once appear, the light did not turn will lead to efficiency is affected by a certain motor controller, we need to take corresponding processing in a timely manner. Dc motor controller light do not turn the reasons are: 1. The armature dc motor controller circuit appear offline; 2. Motor controller of the armature coils in short circuit; 3. A vertical plate or commutator and head sealing off; 4. Motor controller of excitation circuit disconnection. Above points are the cause of dc motor controller is not empty, we need according to the reason to find out the corresponding treatment measures.