For you Prius experts out there, here is a mystery that is even stumping the Prius techs trying to fix this problem under warranty. Here are the facts. 1. The Smart Key works for the rear hatch but not driver's or passenger's door unless the button on the key fob was used to lock the car. If the black button on the handle was used to lock the car, the car does not unlock when the touch pad inside either door handle is touched. 2 If the lock button on the key fob is used to lock the car, the touch pad will unlock the car on either door and when you approach the car the little red light on the fob will blink once as it should and the dome light will come on as it should. If the black button on the handle is used to lock the car the little red light on the fob will not come on and the dome light will not come on. 3. The ignition does work properly with the smart key in the pocket. When the smart key is not working neither the driver's door nor the passenger's door will unlock and it is necessary to use the fob's unlock button. The tech has tried a new driver's door handle with its touch pad and black button but the problem was not solved.
My CX9 Work shop menual has a wiring diagram of SmartKey system similar to the one used on Prius (Denso vs Tokai-rika - same principlae, similar configuration). I read it a couple times before. My best guess to you is that the processing unit of the SmartKey system is probably bad. From what you described, I would rule out sensors and touch pads (what are the chance that both went bad?!). Your tech should be able to follow the workshop manual guidances of debugging procedures and narrow down the problem. Quite complex and lengthy, really. I will bet my money on the processing unit.
Just curiosity here.... Have you checked the battery in the Smart Key fob? I know it seems like a very simple thing, but sometimes the simplest things are the easiest to overlook....
The first thing I did was to put a new battery in the key fob. Good thought though. That could have been the problem but was not.