I have a 500BT, it worked fine in all the functions until one day it failsed in two function. 1. the unit did not sense the phone. 2. the unit did not sense the SD(the SD icon did not light up). Before I was about to send for warranty repair, I call pioneer service department. The technician advised me: 1. delete the phone from menu, let the unit sense the phone again. 2. you probably have some video in the SD causing problem, so format the SD, put some music file into it, see what happen, call us back if you have more problem.
So first, I tried to delete the phone, however, no way, because all the phone setup menu icon did not light up. Then I did the step two, my SD had some video that I download from the computer. I format it, and put some music files only. The unit sense the SD card OK and plays music fine. And incidentally, I noticed the phone was connected to the unit. From these, I know the video file is the evil.
Other time, the unit sense the SD OK, but the unit did not sense the phone, I played around the unit, found one trick. Go the system setup, kick language, kick English, then choice of language comes up, pick Spanish or French, then the system would go through reboot. Then the unit would sense the phone. After that, change the language to English, the phone remain working with the unit.