For the past several weeks, my aftermarket stereo would re-set itself when I was driving over especially bumpy roads. Oddly, when I hit the sides of the radio housing console while stopped, it would never re-set, only when I was driving. The radio acted like the power was cut for a fraction of a second - all the station memory and clock settings were retained, but the stereo would go through the normal power-on sequence and the power antenna would go back up.

Last night, I accidentally brushed my hand past the cigarette lighter **** and the same thing happened. When I moved it with my finger, there was a spark and the Radio fuse was blown. I replaced the fuse and unscrewed the heating element from the rest of the cigarette lighter housing so I could re-install it and not leave a hole in my dash. The heating element was really loose and wobbling in the housing, and I knew I had found the source of the very brief short circuit.

The problem was that hitting a bump would jar the lighter insides so that it touched the ground just for a fraction of a second. Note long enough to draw enough current to blow the Radio fuse, but the quick voltage drop caused the electronics within the stereo to re-set. I wanted to put this story here in case it might help someone searching for a weird, bump-related problem with their radio cutting out. If I hadn't hit the lighter with my hand by accident, I'd still be looking for the source of the problem!