Solenoid switch is the control switch on the start motor, which is one of the three parts of start motor(DC motor, transmission meshing mechanism and solenoid switch). The working principle is that the electromagnetic force is generated after the coil is energized, So that the drive meshing mechanism to move the start motor pinion forward and the engine flywheel ring gear meshing, on the other hand to push the switch contacts connected to the DC motor running, thus driving the engine to start.