While they may look simple, car start/stop buttons are actually fairly complex pieces of technology that make us our everyday lives just a little bit easier.
The Basics
Before we explain how modern start/stop buttons work, it’s important to note that they differ significantly from a traditional ignition key system or even those that use proximity keys. With those systems, inserting a metal key or tapping a key fob turns a switch that sends an electrical current directly to the vehicle’s starter solenoid. When the solenoid receives the electric current, it sends power to the starter’s electric motor, which spins the motor’s gear against a toothed ring attached to the engine’s flywheel, starting the engine.
In contrast, start/stop buttons work in conjunction with the vehicle’s electronics. When you press a start/stop button, you are initiating a request to the vehicle’s Engine Control Unit (ECU). Rather than sending a direct current to the starter like a key, the ECU must verify several critical security criteria have been met before it’s safe to start the engine.
Security
The primary reason for the ECU and start/stop buttons is security. Before the ECU can safely engage the starter, it must verify several different signals:
- The car is in park
- The parking brake is engaged
- The gearshift selector is in the correct position (for automatics)
- The clutch is fully depressed (for manuals)
- The brake pedal is depressed (for some models)
- There’s no other signal suggesting the car could suddenly jolt forward
If all these conditions are met, the ECU will signal the starter to fire. Most ECU systems also feature some type of encryption or other verification protocol that ensures the vehicle is only attempting to start with an appropriate key fob.
Conclusion
Car start/stop buttons may look simple, but they are actually sophisticated security devices. By utilizing an ECU and multiple sensors to verify certain criteria, you know for certain that your vehicle won’t roll away or be started by someone without the appropriate authorization.
