I've got an 03 GT 5 speed with the same flicker problems. No rhyme or reason to this problem. The flickering comes and goes, I can be driving down a country road at night and suddenly the exterior and interior lights will flicker for anywhere from 5 to 15 seconds. Could happen again in one minute, 20 minutes, as I said, no rhyme or reason to it all.
Decided to install the Sun Hyperground system last week. Info about my install is here:
http://www.ptcruiserlinks.com/forum/...round%2CSystem
Hyperground install proved to be no help to the flickering light issues. This GT has been an excellent car but the flickering issue is really unacceptable. I am contemplating getting the local dealer to look at it but trying to get someone to see this issue during the middle of the day might be a worthless cause. If anyone else has any opinions or help I'd sure love to hear them.