If the metal wire is touching the manifold, you have a short (improper ground), and that's most likely what caused the fusible link to blow. Wrap that wire in something to insulate it (preferably electrical tape) and then you can try Jeremy5848's test above.

From other posts, I understand the fusible link is cheap to replace. That should be your next step before dropping $100+ on a new relay.

But if the insulation has gone bad at one spot on your GP harness, you need to inspect the whole thing for other trouble spots, and for continuity.

A word of caution: You can use a typical multimeter to test GP resistance, cable continuity, and in/out voltage, but not current draw. Most multimeters can't handle more than a couple of amps, and these GPs can draw a lot more than that.