Look at the diagram I posted at post #4 above, that RD (red) is the circuit that's shorted to ground. The 'ALT' that is on different circuit and the wire color is NOT red anymore. Refer to that diagram # 4 again, you can see the wire color is YE (yellow) from the relay going to the fusible links, you don't need to look this far.
I mentioned about aux battery, you will need to check if the battery is present, not only that you also need to check its wiring as well. Your previous owner might have aux battery installed previously but if the wiring is still intact it can also short to ground. Remember the RED wire that's the entire circuit to check. If something is short to ground on the YE circuit the fusible links should have blown already, you can verify that as well, pop the black cover you can see them.

 

Your reply, should be "post # 12" doesn't show up. yours becomes post # 13 now. Contact the admin to fix that.
In fact your other replies didn't show up until the admin fixed those this morning.