Starter solenoid
（重定向自Starter relay）
![The starter solenoid is above the starter motor. The threaded terminal at left would connect to the battery through a heavy cable. At the right end of the solenoid coil, a linkage inside the housing would engage the pinion visible in the housing at the right side of the motor.](/Images/godic/202502/13/Automobile_starter1258.JPG")
A starter solenoid (or starter relay) is the part of an automobile which switches a large electric current to the starter motor, in response to a small control current, and which in turn sets the engine in motion. Its function is thus identical to that of a transistor, but using an electromagnetic solenoid rather than semiconductor to perform the switching. In many vehicles the solenoid also engages the starter pinion with the ring gear of the engine.