In my many years of experience I have learned that you can never overlook the easy and obvious first step. Even if they are on the same fuse (which they're not), you never know when the factory wiring has been messed with in any way until you have some electrical issue. Pull out each fuse individually and physically look at them to make sure they are all good. If they check out then most likely, the plug came undone from the back of the lighter. It could be the ground, but the plug coming undone is more likely. BUT CHECK THE FUSES FIRST! lol