Hello from Germany.....i hope for help....
 

Hey I am Chester from Germany,

Having with you in the forum announced because I am found no real help here with myself. I drive the 97th blazer (model 98). Actually, I always go with rear-wheel drive, however, 4x4 I would like to use him also with pleasure. but if I on 4hi or 4lo press it does only once click and the lamp flashes once briefly. Then 2hi lamp shines again. Do you know this problem, or do you know where I after a mistake should look? This would be really nice from you!!

I am soory for my bad english!!

thanks

Here are some threads to get you started:
4x4 No Worky.... Maybe this will help....

You can also check all of the connections at the switch (dash), TCCM (I believe this is located under the dash near the passenger side of center on the 95-97 models), and the encoder motor (on the transfer case) for corrosion, cleaning as required.