Image Gallery: Car Gadgets
Image Gallery: Car Gadgets

Key fobs such as this one activate the power door lock mechanism. See more pictures of car gadgets.

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Between the keypads, keyless entry systems and conventional locks, some cars today have four or five different ways to unlock the doors. How do cars keep track of all those different methods, and what exactly happens when the doors unlock?

The mechanism that unlocks your car doors is actually quite interesting. It has to be very reliable because it is going to unlock your doors tens of thousands of times over the life of your car.

In this edition of HowStuffWorks, we'll learn just what's inside your door that ma­kes it unlock. We'll take apart the actuator that does the work, and then we'll learn how the lock can be forced open. But first, let's see how the car keeps all its signals straight. ­