How does a key fob work?
On a fob, there are multiple buttons, one of those buttons
unlocks the car. Another one of them locks the car. One of the
buttons pops the trunk and the last button turns on or off the
alarm. On more advanced models the radio frequency fob can also be
used to open the trunk or even remotely start the vehicle. My
current one allows me to lock, unlock, remote start, open back
hatch, open back window and alarm.