i have a 98 s10 blazer and 4 low works and i cant figure why 4 high won't work. does anyone have any ideas why??

 

Could be a number of things... Faulty encoder motor. Bad switch. Failing TCCM. There is a LOT of information available.

 

where can i find the troubleshooting info i need

 

The Tech Article (DIY) section is a good place to start, but a few searches should get you some reading material. Check out the search guidelines link in my signature for some tips on searching. Try to refine your search after reading a bit. As I said, there is A LOT of information on 4wd problems out there.

 

the tccm has been replaced as well as the switch.