One way is to listen for a clicking sound when you turn the key in the ignition. If you hear a clicking sound, it means that the solenoid is working and the problem may lie elsewhere, such as with the starter motor or the battery.
Another way to test the solenoid is to use a multimeter to check for continuity between the solenoid's terminals. If there is no continuity, it means that the solenoid is faulty and needs to be replaced.
Finally, you can also try tapping the solenoid with a hammer. If this starts the car, it means that the solenoid is sticking and needs to be cleaned or replaced.
The location of the starter differs significantly by make and model, but you'll usually find it near the back of the engine or on top of the transmission: Look along the engine block: The starter sits near the end of the block of cylinders. Locate the transmission bell housing: On all cars there is usually a hump at the rear back of the block. Check near the clutch assembly: On rear-wheel-drive cars with manual transmissions (the vast majority) the starter usually bolts onto the bell housing close to the clutch assembly area at the bottom rear of the motor.
