Article: A couple of things might happen when you do this. If the car makes a noise like it’s going to start, but the headlights dim, then the starter pinion is probably jammed. If the car makes a clicking noise but never sounds like it's trying to start, and the lights dim, then the problem is likely the battery. Skip to checking the electrical system. The starter is a large electrical motor in a cylindrical housing, and it's usually bolted to one side of the engine block. If you see a small, square stub (the pinion stub) sticking out of the end of the cylinder, turn it with your wrench until it moves freely in place. Try starting the car again once the pinion can move freely.  In modern cars, you'll find the solenoid (which is a smaller cylinder) attached to the starter cylinder, "piggyback" style. They'll be separated and connected by a thick wire in older cars. Refer to your owner's manual for help finding these components. Turn the car off and put it in second gear. Release the emergency brake and rock the car back and forth. This can loosen the pinion. If you don’t see a pinion stub and you have an automatic transmission, you will have to take the starter motor off and bench test it.
What is a summary of what this article is about?
Turn on the headlights and try to start the car. Turn the pinion stub with an adjustable wrench (spanner). Rock the car if you see no stub and have a manual transmission.