Well if its the fuse, the dash lights is on the same circuit as the parkers... So if you blow one, normally the other goes out.
someonestolecc : nah, i've seen people blow up the speaker channels, and why the problem above occurs is generally if you dont run an earth through the chassis, but insted use the one in the plug. The one in the plug is sometimes used as a "dimmer" wire, so that when you turn your parkers on it changes its polarity
Cheers
Sumo