well here's my 2 cents...does it happen all the time? if you hit the 4wd then the 2wd button...does that make it stop? my suggestion is the transmission....there's a gear....after a while...there's no more grip..and no more transmission...it's personal experience...(sorry I can't explain it in technical terms)

 

no, it does not happen all the time. it only happens under very specific conditions.

the 4wd will not disengage unless the engine is shut off, so i cannot answer your second question.

 

well the reason I asked..I have a 200o blazer...and for about a year...when ever the cruize had been on for a while..and I'd step on the brakes..or slow down..to exit.or what ever...I would hear this horrible..I thought more of a grinding sound..but it was kind of wailing too...well no one could figure out what was wrong..and it would only happen in senarios similar...soooooo.....I used to be able to hit the 4wd button..and then 2wd and fixed the issue...sometimes I would have to pull off and put it in reverse....long story short...one day I went to step on the accelerator and there was no acceleration...and then I lost reverse....ended up needing a new transmission....it was a gear in the blazer transmission...I guess you can replace the gear before the whole thing blows....I got a used one for not too much money......

 

anymore input on this problem before i dig into the transfer case?

 

I found this thread during a search, so am bumping it up. I am having the exact same issues. Anyone add anything new? A significant grinding/howling sound on decelleration, only occurs occasionally, and goes away if you hit the 4 wd button. I am theroizing that maybe the solenoid that engaged either the axle or transfer case is partially engaging on its own for some reason, but its pure speculation.

Thanks!

 

i know exactly what it is, i think, haha anyway i had this very same problem, it was the vacume switch that engaged the front differental
could be two things
1) the actuall switch here is a link to that vacuume switch -that is one online, i needed one right then and paid $40 from a dealer
how to get to it--- under the car on the transfer case this screws into the top( its on the drivers side) this is what it looks like with the tube on to pic
and that can be found HERE
u may need a new one of those or :
2) or may need this:actuator That is found underneather the batterie and the box it sits in. The bolts for that are acseeable from the wheel well

3) or both or the cable that ataches to the actuator,but i doubt that sence this only happens sometimes

hope that helps you , sorry for the errors in the typing its my first real right up of a fix for a problem

 

What quantosh said.

I had the same problem with mine, and it wound up just being the vacuum switch on the transfer case.

 

by the way if you don't fix it...you will need a new transmission.....it will wear your little gear down until it's gone....

 

still haven't determined what the problem is. i thought i fixed it by reconnecting a vacuum line in the dash, but the problem is still there - it just doesn't happen as often (could be the fact that the weather is warmer now). it has been kind of rainy lately, so i haven't had a chance to check things out.

 

Thanks guys, I am fairly certain its the vaccuum switch on the t-case. I will pick one up today and give it a whirl. Problem is, the syptoms are so random I'm not going to be comfortable that it is or isn't fixed for quite some time. I will try to remember to report back.

Thanks again for all your input.