New owner, key issue...

[unadilla66]

Just bought an '07 Yaris. Seller only had one key- black with 4 remote buttons. I got a 'regular' copy of the key, only to find that the keys (including the black remote one) won't open any of the locks- though they do start the car (including the new copy), and the remote unlocks it. I'm guessing this means the car doesn't have the 'immobilizer,' since the copy starts it. But seems weird that the ignition key doesn't open the doors- I assume originally the ignition and doors were keyed the same. I don't like the idea of not being able to open the car if the battery in either the key or the car dies.... Wondering how hard it is to get the cylinders out of the doors, then maybe I could take them to a locksmith and have it set for the key(s) I have to work...? And in the meantime I'm ordering another remote key and hoping the tutorial here will get me through programming the remote to work with the doors.