How Do Cars Start With the Push of a Button?

If you were a driver in the early 1900s, hitting the road would be far easier said than done. Step one, engage the hand brake. Step two, pull the choke. Prime the engine, set back the spark, open the throttle, turn the key, and engage the crankshaft before finally heading on your way. Not only was this process laborious, but it was also somewhat dangerous (giving a very real meaning to the term “backfire”). 

Thankfully, it didn’t take long for the process to be simplified and mechanical keys to gain traction. But in the last 30-odd years, key fobs and push-button starts have replaced physical keys. So how does your car start with the simple push of a button?

The ‘Silent’ Dialogue Between Your Car and Key Fob

First, the car must receive the signal from the key fob. A typical car will constantly be broadcasting, or “polling,” at a low-frequency (around 125 to 135 kilohertz), and when the key receives this signal, it broadcasts back an encrypted, higher-frequency code at around 315 megahertz. The car’s onboard computer checks this code to confirm entry, and once matched, the car unlocks.  

When you press the push-to-start button, the car’s computer performs a series of electronic safety checks, making sure your foot is on the break (so that the car doesn’t roll away if it’s in gear), for example. If all’s well, once the push-to-start is engaged the car sends a current from the battery to the electric starter whose sole purpose is to transform electricity into mechanical energy. 

Using magnets, a rotor, and stator, the starter almost instantly rotates the pinion gear that engages the flywheel thereby starting the engine. Electric cars, on the other hand, skip this complicated last step as they don’t need initial cranking to start their motors like internal combustion engines. 

Push-to-start systems come with their fair share of headaches, such as dead batteries and some vulnerabilities to hacking (though fobs do use encrypted RFID codes to avoid unauthorized access). However, the new-and-improved ignition system is an all-around net benefit as keyless ignitions can’t be hot-wired. 

They also don’t wear out over time, and they reduce the possibility of overcranking, which can damage the starter motor and drain the battery. It’s why almost every car made today has fully embraced this push-to-start innovation some 30 years after its initial introduction.