Thanks for reading the post

I've read many threads on my issue but I cannot get to the bottom of it.

I'm a fairly competent home mechanic, but electrical gremlins I cannot easily fix.

I have the following issues:
1) 4 hi blinks when button pressed, clicking from box, and a short mechanical sound
2) 4 lo blinks when button pressed, no clicking no mechanical sound
3) if I press 2 hi there is a click, followed by a 2 second mechanical sound, then light stops flashing a remains on.
4) there is a hole on the side of the vacuum switch on the bulkhead is this meant to be there, air comes out it when I depress the rubber diaphragm below the battery tray. The hoses aren't leaking as I sealed and blew into them with no leaks.
5) I directly joined the two hoses going into the vacuum switch with a female to female adapter and it does as above 1-3) ie not working
6) I followed the vacuum hose over to the far side and there is one hose that disappears into the wheel arch. When I blow in that pipe I can hear air escaping, is this normal?
7) my courtesy light fuse blows immediately as soon as I put a fuse in.
8) I removed the two connectors from the box behind the plastic cover on the passenger side - is this the tccm? The connectors four of them were corroded. I cleaned then and applied dewatering solution. When I reconnect the connectors the box clicks so I presume it is working.

Any suggestions please? The RHD blazer is rare in my country so no one know much about them. I'm probably on my own here.

 

It looks like the cause of the fuse blowing is corroded connectors on my TCCM. I plugged it out, and the fuse no longer blows. But the connectors are so corroded I cannot get them cleaned again. Any of the scrapyard blazers I've tried to slavage another plug from are also corroded.