transfer case problems

i have read all the other threads about the auto 4 wheel drive lites blinking and some of them sound close , when i try to engage to 4 wheel drive 4hi or 4lo the lights blink and sometimes it will engage in 4lo , by reading it sounds like the transfer case shift control switch , can i do this work , where is the switch located ,or is it something a local shop should do ,i am an ok mech and know my way around the tool box any help would be appreciated .