New prius - Fobs don't work well?

rolling codes are an interesting thing

codes dont actually 'roll' in a rolling code system. i think it works more like this: Fob sends a 'hello, i want to open the car' signal. then the car sends a 'challenge such as (what is you name? what is your favorite colour? and what is the air speed of an unlaiden swallow) just kidding on this part '. if the fob then responds with the correct answer, the car unlocks. the 'rolling' is from the change in the challenge the car sends. since it never asks the same question twice (most likely random), you cant replicate the signal the fob sends out to open the car.
so there is no 'sync' involved in a rolling code mechanism

 

This site has an explanation of the "rolling code"
http://electronics.howstuffworks.com/remote-entry2.htm

 

Challenge/response may (repeat, *may*) be more secure/reliable than rolling-code, but it's more difficult (read: expensive) to implement, as it requires two-way communication between the car and the fob.

I suspect that the immobiliser function may be challenge-response, as this is close-range, and the fob is then powered from the slot. But I'm not sure of this.

I guess SS/SE has to be challenge-response in order to work at all, since the car is the initiator, not the fob, in this case. But it's possible that the challenge is non-unique and all it does is trigger the fob to send the next rolling code.

 

Re: Signal could be blocked

I think I read in the owner's manual that you should keep it away from cell phones and PDAs. Not that they gave specifics as to how far was far enough or what would happen if you didn't

 

Yes, in June at Logan airport. The airline called to tell me my neice was waiting. The plane had landed 40 minutes early and there was no indication on the monitors so I was just hanging by the security doors. I was puzzled that I got a message but the phone hadn't rung. Oddly enough, I was able to call in and retrieve the message without moving.