RE: no fuse error code
Do you have a second fuse panel in the interior somewhere? Many vehicles do. Also, not being familiar with the wiring harness colors used in your vehicle, is the yellow line supposed to be switched (by ignition key) or is it supposed to be continuously hot? My guess is that you have a second panel, though I'm not familiar with PT Cruisers, (My Sebring has one) and the interior fuse is blown.
One other thing... Are you replacing a factory radio, or an aftermarket one. If the old one is aftermarket, look for an inline fuse somewhere. (Though I doubt that the blown fuse indicator in your odometer would recognize that.)
Fellow Chrysler Owner