Here is a strange one. Have an 02 GT conv, automatic with all the bells and whistles including the Mach1000 stereo. The radio turns on while the shifter is in park and neutral, but when you put it in either R or any of the D 1,2...it turns completely off with the LCD display completely blank. It does this whether the engine is running or not. The shifter only has to partially leave the P or the N, but does not have to engage the gear. It does it reliably, not intermittently. I don't think it is a ground issue, as when the radio does come back on, it still has all of it's memory and is on the same radio station and time is correct. It did this once before about a yr ago. I took the dash and radio wiring all apart and never found anything obvious, but when I put it back together, the problem disappeared...not sure if it was one of the connectors or just coincidence that it fixed itself. I was just glad I had tunes again.
BUT, what the heck does the shifter have to do with anything? the only thing I can think of is maybe the reverse lighting circuit, or the convertible top switch circuit (car has to be in neutral with pk brake on to work the top). No wiring is close to the shifter, so I am at a loss as to why this is happening....Help me Mr Wizard!