Chevrolet Repair: 2000 Blazer ZR2 Question, blazer zr2, vacuum switch

Question
Mark, I noticed that the last time I have the vehicle serviced the 4 wheel low button was activated. I shifted it back to 2 wheel high and didn't think anything of it until a couple of miles down the road when the noise started. Now sometimes when I take off slow or when I carry a turn at speed a growling noise in the front passenger wheel area starts. As I slow down the noise sometimes gets louder and sounds like a gear is rubbing then finally catches and will go away for awhile. Any thought on what is wrong?  

Answer
Hello Mike, This is a bad transfer case vacuum switch. You need to either replace it NOW or run the truck in 4 Hi. This will keep the gears in the front differenial from grinding. If they grind long enough it won't lock into 4X4. Then you will have to replace them too. The vacuum switch is leaking vacuum by and only slightly applying the front end grinding the gears..

Hope this helps

Mark