Starter Motor Diagram: Beginner’s Guide With Pictures

Starter Motor Diagram

The starter motor is a critical component of a car’s electrical system and is responsible for starting the engine. It is an electric motor that is used to turn the engine over and start the car. It is turned by a key or a button, which activates a solenoid that turns the starter motor. The starter motor is powered by a battery and turns the engine over until it starts.

It works by converting electrical energy into mechanical energy, which then turns the engine over. The starter motor is typically located at the front of the engine and is connected to the battery. When the starter button is pressed, a small amount of current from the battery flows through the starter solenoid, which activates the starter motor. This article will provide a diagram of a typical starter motor, as well as an explanation of it.

Starter Motor Diagram

Starter Solenoid Terminals
Starter Solenoid Terminals

A starter solenoid has three terminals, one small pin-type terminal, and two thicker bolt-type terminals. The small pin-shaped terminal is called the S terminal. The “S” terminal links with the ignition switch circuit. The starter solenoid has one thicker terminal as the input terminal, where the battery positive power source enters the solenoid, and the second thicker terminal is the output terminal, which goes straight to the starter motor assembly.

Car Starting System Circuit
The Starter Motor Wiring Diagram

Remember, the starting motor uses two wiring circuits to complete its operation. The first one is the control circuit, and the second one is a heavy electric circuit. The control circuit turns ON and OFF the solenoid and is controlled by the ignition switch. It consumes less current, and these cables are thin compared to the second circuit.

Car Starter Motor Control Circuit Diagram
Car Starter Motor Control Circuit Diagram

The control circuit starts from the ignition switch and goes to the starter fuse then to the neutral safety or clutch pedal safety switch to the starter relay in the fusebox and finally to the starter solenoid “S” terminal. The second circuit is a heavy-current drawn circuit. This circuit goes directly from the battery through a heavy cable to the solenoid and then to the starter motor assembly. When activated, the starter motor armature turns.

When the driver turns the key to the start position or presses the start button in the keyless car, the current flows from the ignition switch or ECU to the starter fuse to relay in the fuse box. This fuse box starter relay provides a bigger current to the solenoid.

You may be wondering at this point by knowing that the solenoid itself acts as a bigger relay and gives an even larger current to the starter motor. In general, a relay is needed to control a larger current by using a smaller current.

The starter motor is a huge energy sucker. It consumes a lot of power, you cannot control it from the ignition switch it can damage the ignition switch. So a starter solenoid is introduced to control the heavy current by using a low current.


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