How Does a Car Starter Work?by Cayden Conor
Without a starter, a car will not be able to start. A car starter is found near the transmission, as it must extend the starter gear into the flywheel (flex plate for automatic transmissions). The flywheel or flex plate is a toothed gear that is attached to the back of the engine, between the engine and transmission.
The starter is composed of the starter itself and the starter solenoid. The solenoid is generally on the starter, but on some older cars, particularly Fords, the solenoid may be on the fender wall. The red power wire that is attached to the starter solenoid runs directly between the battery and the starter solenoid, and is protected by a starter relay.
When the key is turned to the start position, an electrical signal is sent through the microchipped key (if applicable). The signal is then sent to the body ride control module or the computer (depending on the year, make and model of the car). The signal must then go through the burglar alarm, then through neutral safety switch, (if the car is a manual, through the clutch switch) to the solenoid, which pushes the bendix out, engaging the starter gear with the flywheel or flex plate and turning the gear. The starter gear turns the flywheel or flex plate, which in turn turns the engine over.
If the microchipped key does not give the proper signal, the car will not start. If there is a problem with the neutral safety switch (this switch does not allow the car to start unless it is in neutral or park), it will not allow the power to finish the circuit, and you have a no-start situation. If the burglar alarm is malfunctioning, or if the car was stolen without a key (hot wired), the power will not complete the circuit through to the starter and the car will not start.
A starter is not engaged all of the time. It only engages when the key is turned to the start position. When the key is let out of the start position, the bendex releases the starter gear from the flywheel/flex plate. If the key is turned to the start position when the car is already running, the bendix activates, pushing the starter gear into the already turning flywheel or flex plate, which makes a loud grinding noise as the moving gears try to mesh. Done often enough, this can break the teeth on the starter gear or the flywheel or flex plate.