In this case you have to determine how the short occurs. If the fuse blows as soon as you shift into reverse, even when the engine is not running, that is different than if the engine has to rock from being shifted into reverse while it's running. Rocking suggests a wire is rubbed through and grounding out so you would look for wire harnesses that move when you shift between drive and reverse.
Either way, 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.
Friday, May 3rd, 2013 AT 7:26 PM