99 blazer 4x4 issues
 

So yesterday afternoon I noticed my 4hi was on and it won' go into 2hi or 4lo. It doesn't have the auto 4wd just 2hi 4hi and 4lo. When I push 4lo in neutral it will flash normally but won't switch over. Then when I push 2hi it will either only blink once or not at all. I hear a click under the dash but that's it. I fixed a vacuum leak on the driver side engine bay. Then there is another line that was burning on the exhaust on the passenger side that y's together too 2 other lines and can' find where it connects too.