With A Test Light or Digital Multimeter (DMM)

1. Remove the blown fuse and disconnect the load.
2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered).
3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DMM.
4. when the test light glows, or the DMM registers, there is a short to ground in the wiring near that point.