Motor controller failure is a cause of the dc motor controller cannot be started. What can we do? Below small make up to tell you. Motor controller failure likely scenario: worn brush dc motor controller, jam, spring pressure is not enough, make the brush and commutator appear poor contact; The armature winding appear disconnected; Excitation winding is a disconnect, and no residual magnetism, etc. Measures taken are: to solve the problem of the use of multimeter resistance check between brush and commutator segment at the ends of the contact resistance, and the winding resistance. If the resistance value is large, then there is fault, for further check, find and repair the breakpoint.