You know what I do believe the previous owner put some sort of aftermarket speaker in up there because a speaker clips onto my sun visor and the wire is coming from under the plastic panel over my head.This area is usually where the wiring damage happens.. either at the joint between kick panel plastic and the door sill plastic, where the debris makes its way down there and eventually gets compacted into the wiring channel, or from previous work in the channel (people running aftermarket speaker wiring, etc.) and they don't get the wiring back in the channel correctly, and nick/pierce it with the sill screws.
Richard