I blew the "main" fuse on my 87 TII. I've got it replaced after putting in a new fuse block (old one crumbled when I removed bolts), but have no power to anything that passes through the ignition switch. Have 12.4v to switch on white/red wire (switch side) at off position. When switched to ACC/ON/START, I get ground to all soldered points on side of switch. I know the switch is bad. My question is if I need to troubleshoot further before popping it a new one in & possibly destroying it? Could the failure of the switch to all ground causing the fuse to blow be the only thing going on here? I'm sure the switch shorting to ground would cause it to blow, just not sure of the cause/effect situation here.

 

Replace the switch. the fuse will blow before the switch. The switch most likely caused the fuse to blow (if it is shorted to ground).