#3 fuse keeps blowing ---I'm lost here-HELP!!!

The #3 fuse on my 300e keeps blowing. It seems to control the passengers side corner light, the passenger side taillight and the dashboard light. The car is equipped with new aftermarket tailights but the connections seem to be fine and the housing on them is ABS so there can't be any short across the housing.
Short of going to a dealership, is there a way to isolate the problem here. It is my understanding that this is not an uncommon problem with the 300e
Any helpwould be greatly appreciated. Thanks

search for chaffed or broken wire rubbing near light connections