The starter is an electric motor that sets your engine in motion. When you turn the key or push the start button, the battery sends electrical energy to the solenoid that activates the starter motor and turns the flywheel to begin the engine.
When you get your car stuck in traffic and the starter won't start, there are a few things you can try. Rocking your vehicle back and forth or tapping the starter with a hammer should help you start it again, but these methods can be temporary.
When the starter motor won't start, you can try connecting a jumper cable to your positive terminal on the battery. If your starter doesn't start, this usually indicates a problem with the battery or the solenoid.
If you have a bad starter, it may have accumulated dust, rust, and acid deposits in the area of the starter motor, the solenoid, and the ground wire. Tapping the faulty starter gently with a hammer can remove these dead spots and make your car's starter work again.
The short-term fix of applying this technique to a faulty starter is only effective if there's enough electric contact between the carbon brushes in the starter and the commutator. These brushes can become rusted, so they won't make any electrical contact with the commutator when the starter motor rotates.