Like most powerful motor and electrical devices in your car, the starter does not draw its power directly from the switch used to activate it. Instead, the switch triggers a sort of secondary switch, known as a relay or – in the case of a starter – the solenoid.
Starting System Fundamentals
When the ignition key is turned on your car, the key is a gap between the positive battery cable and the positive terminal of the starter solenoid is closed, the circuit is closed when the solenoid, a switch inside the solenoid closes and closes another circuit connecting the battery and the electric motor in your starter. Hypothetically, you could run a cable directly from the battery to the ignition switch and then to the engine, but that would require a lot of very heavy gauge wire and a heavy duty switch.
Solenoid how it works
When electrical current from the switch enters the solenoid is energized a small magnet inside the solenoid. This solenoid pulls a metal arm attached to the positive terminal of the battery against a metal plate on the starter terminal. Thus, the starter solenoid mimics the behavior of the switch, you can think about the starter solenoid as a second power switch is located on the dividing line between the battery and the starter.
Divorced vs. integrated
Typically use a modern start starter solenoid integrated into the body of the owner himself, while older cars often use a divorced solenoid mounted on the wheel or firewall. The integrated solenoid and starter pack is cheaper to produce and install, reducing the number of connections in the electrical system and the processes required to install a solenoid mechanism separately in the engine compartment of the machine. To locate the starter solenoid – either divorced or integrated – just follow the thick wire, red connected to the positive terminal of the battery.
Failure and troubleshooting
Click starter solenoid usually indicates low battery. The main closure starting circuit draws a lot of battery power, which temporarily deprives the power switch on the intensity of current needed to activate the solenoid. When the primary circuit is opened, the energy returns to the electromagnet, the circuit is closed with a thud and the cycle begins again. In this scenario, divorced solenoids have a slight advantage over integrated solenoids, and a driver can simply skip the exposed battery terminals and starter solenoid with a screwdriver. This prevents the set of on-off-on cycle, possibly allowing a driver to start the car when it otherwise might end up stranded. This may be technically possible with some integrated solenoid, but the solenoid is formed by nature hard to find.