That circuit usually leads to the generator's output terminal. Measure for voltage there. If it's missing, disconnect that wire, then measure for continuity to ground from the wire and from the output terminal. If you read continuity to ground on the output terminal, replace the generator. If you read it on the wire, look for a place it's rubbed through and grounding out.
October, 6, 2012 AT 9:26 PM
The 100 A fuse is the main fuse for many components but since othere smaller fuses are not blowing, the one that mainly feeds off it would be the charging system, meaning the alternator. Disconnect the alternator main wore and tape it up and test if it shorts.