do you have a multi-meter? how 'bout a test light? if not get a multimeter and the haynes or similar manual for your car. you might be able to get the wiring diagram from autozone. according to mine the gray wire comes out of the fuse block and goes to the instrument cluster, radio, ashtray or console shift light, heater a/c switch light, defog controller, and 85/earlier the clock light, wiper switch, and illuminated trim plate. this is from a monte manual but should be close enough.
using the multi-meter on the continuity setting, with the black (-) lead connected to a good body ground and with the car power off probe the ends of the connectors. if you have continuity to gnd on the gray wire on one of the connectors, that's the bad wire. now you have to inspect it for the bad section and replace it.
one other thing you can try is to unplug all the loads and then put in a fuse and turn on the power. if the fuse doesn't blow, plug everything in one by one until it does. the component that blows the fuse is bad.