Q: How Does a Keyless Push-Button Ignition Work?

asked by on

How does a keyless push-button ignition work?

Push-button ignition system designs are highly technical and vary between manufacturers. Here, in a nutshell, is how they work.

When you push the “engine start” button, that button sends an electrical command (voltage signal) to several control modules (computers). One control module (we’ll call it the body control module) uses antennas located inside your vehicle and sends out a radio signal to the key in your pocket. This reaction wakes up the RFID chip inside the key, and asks it to identify itself. The RFID chip in the key responds to the ID request with a radio message of its own where it sends its ID code back to the body control module.

The other control module that received the “engine start” command is the engine computer. We’ll call it the powertrain control module (PCM). The PCM is ready to start the engine, but it needs information from the BCM first, since the BCM controls the keyless entry system of the vehicle.

If the BCM accepts the RFID code from the key, it communicates this to the PCM, and the engine start is enabled. If an unprogrammed key is used, the BCM rejects the key code. The reject notice is communicated from the BCM to the PCM and the engine start is disabled. All of this communication occurs in less than 1/2 second!

This same process occurs to automatically unlock the doors of your vehicle whenever you grab a door handle.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. How Does a Keyless Push-Button Ignition Work?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Keyless entry and remote programming

Hello. Reprogramming the immobilizer system of your vehicle is very pattern sensitive process. All the steps have to be completed in a near perfect sequence or else the reprogramming may not register. It usually takes someone, possibly even some technicians...

Q: Broke key triggers anti theft system on 2011 camaro.

The broken key set may no longer be giving off the signal saved in the vehicles anti-theft system. If the vehicle cannot verify the signal for the key, it will not start as if someone was trying to steal the...

Q: Engine will not stay started. I have replaced idle control valve map sensor spark plugs spark plug wires no check engine light is

You have a problem with the distributor assembly. I recommend replacing the distributor assembly. This will replace all the possible sensors and coil for the ignition and fix the problem you have.

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.