Do you have a wiring diagram? If not, get the model and serial numbers from your machine and go to the Scag website, click on manuals, find your model and serial number group and download the operators/parts manual.
The complexity of the electrical systems on ZTRs makes a quick diagnosis in a post here very difficult. However you can inspect the wiring looking for a chaffed wire or another irregularity that may be visable.
Several steps to check out:
While sitting in the seat, key in on position but engine not running, does the fuse blow?
Cranking the engine, does the fuse blow?
Only after engine start, does the fuse blow?
Is the fuse in the yellow wire OK? This fuse is in the output of the charging system before the key switch.
