4wd

My 1997 Blazer won't shift into 4WD (hubs won't lock). I followed a vacuum hose up to what appears to be a vacuum switch located underneath the battery seat. This vacuum has a light rubber boot over it which is ripped. Could this be my problem? If not, any other ideas?

Yours truly,
Stuck in the sand!

That defiently is a problem. Its torn and needs to be replaced. Also check and make sure in you vaccuum lines you have no transmission fluid in them. Look at the actuator(inside the ripped spot) and see if its oily.