I like using a sealed beam to test for shorts. take a sealed beam headlamp. add some leads. put terminals on the end of the leads that will plug into fuse panel. remove fuse. plug leads into fuse panel where fuse terminals were. with a short present, the sealed beam will be bright. once the short when the short is gone, the lamp is dimmer or out. also with the sealed beam in the circuit, anything that works normally, isn't shorted so you can quickly eliminate circuits. sometimes the shorted circuit gets warm to the touch, which also helps.