Car Keypad

Thanks!

So the 1N diode keeps the current from flowing backwards, the zener diode would cut out voltages above 15v, and the choke would clean up the power a bit. What exactly do the two different caps do? Decoupling to clean up the power? Something else?

I assume that everything to the right of C3 I should ignore, as I don't want to reduce the voltage to 5v?