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.
You may run into an additional clinker in that the flasher may not operate with the added resistance of the test bulb, or it may START to work properly because there will no longer be a short circuit. Given that the problem has steadily gotten worse, look first for wires that have rubbed through the insulation. A common cause is chewed up wires for the trailer connector.
Tuesday, July 15th, 2014 AT 7:29 PM