My mother has a 99 chevy blazer. 4.3 w/the auto/electronic 4wd, i think something like 55-60k on it. She doesnt abuse it, just drives it. LOF, and general insepction every 3-4k..
Um til now whenever shes used it, its gone in no prob. Went to use it today(as we got 18-20" of snow and still snowing:ro) ) pushed 4hi and all it does it just blink. Vechile still moves and everything, just never seems to engage. I tried auto 4wd and did same thing. Didnt even bother w/4lo. I let it sit fer almost a min blinking but never went. Tried goin F &R no difference.
Any ideas? No service 4wd light or anything either...
Thanks-Adam

I had a 98 S10 after 4 years of trouble free winters it dropped below freezing one nite, went for the FWD and nothing? Next day above freezing FWD worked fine although slow to enguage. Found water in vacuum lines to selector switch on transfer case. The FWD always quits when you need it the most. Anyway I found the best way to keep it clear IIRC was to start the truck slide under the left side reach up and unplug vacuum switch to clear the water. For some reason the water always seemed to be on the vacuum supply side. Never did find any vacuum leaks that could have pulled the water in. Good luck.

Blazer 4x4 problems are a can of worms, it could seriously be anything. I have seen bad encoders, switches, solenoids, and modules. You would be better off having it diagnosed by a good shop, as I have seen many people get screwed my misdiagnosis on T-Blazers...