What Are the Functions of a Car Starter Relay?

A car starter relay, also known as a starter solenoid, essentially starts the motor. Without this component, the car cannot run. It works with the car's battery and the ignition to start the vehicle.

Definition

As its name implies, the starter relay starts the engine using a primary electric charge from the car's battery and a smaller current produced by the ignition switch. Car starter relays are typically built into the starter motor.

Function

Car starter relays are comprised of a wire coil that is wrapped around a piston. Electric currents pass through the wire and create a magnetic field. The car starter relay sends the electric current to the starter motor. The starter motor then activates the car engine. The car starter relay also engages the starter pinion with the engine ring gear in many vehicles.

Problems

A car starter relay can fail to activate the starter motor due to insufficient power from the car battery. This can occur due to a damaged positive battery cable, a low or dead battery or loose battery cable connections.

References

• Driver Side: Starter Solenoid
• "How Cars Work;" Tom Newton; 1999

Resources

• "Auto Upkeep;" Michael E. Gray; 2007