A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.
The bulb will limit current to one amp, a safe value that will protect the wires, but that is not enough for those circuits to work. Once the short is repaired the circuits will work again when a new fuse is installed.
Given your description of the symptoms, it suggests the intermittent short is before a switch since you didn't have to activate one to blow the fuse. With the circuits affected there's going to be two likely places to find the cause of the problem. One is broken or frayed wires between the door hinges, and the other is under the seat.
Friday, June 28th, 2013 AT 10:03 PM