Pedal position sensor problem?

I went to Auto Zone and they hooked up a scanner that came up with the "pedal position sensor" code. They cleared the code with the scanner and the car drove like it was fixed. But it came back the next day.
So I'm guessing the sensor is bad. Or are there any other options? Like faulty wiring maybe?
1st of all, can anyone explain where this sensor is or provide a pic?
2nd, is there any way for me to test the sensor, wiring, etc to make sure exactly what the problem is?
3rd, where can I get this sensor if I need it? I haven't found any place local that has it, but I haven't been back to the Toyota dealership to see if they can get the part.
Thanks for the help!




