Can anybody verify this article. http://answers.yahoo.com/question/in...1200636AAictFZ I will put the quote in below.


from the article
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Hi Ivone,

Your Blazer shouldn't have a vacuum switch.
In the passenger side kick panel there is a Transfer Case Control Module. (TCCM) You might have heard a clicking sound coming this area...

I've recently repaired two 2000 Chevy 4X4's with basically the same troubles (no 4 wheel drive).

This a known issue with these trucks, problems with corrosion built up on the pins (contacts).

You can clean the contacts of both the harness and the motor and apply die-electric grease to them and you should be good to go 4 wheelin... Hope this solves your problem!!

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I cannot find the TC Vac Switch. The Actuator under the battery leads right down into the Transfer case on the passenger side. It does not go to a Vaccuum Switch as described elsewhere on this forum.

The prob I have is some times the Right front end will sound kind of like a roar when getting to about 30 mph. If I stop and put in to 4wd and back to 2wd it will stop doing that. So I think the 4wd is trying to engage partially at times.

Please advise. Thanks.

 

This has been described in many other threads on this forum, but for you to ultimately find the answer, you need know what you have...

Do you have the 4 button switch (NP236 or NV236) on the dash or the 3 button switch (NP233 or NV233)?

If you have the 4 button switch on the dash with the automatic option, you will not have a mechanical vacuum switch on the transfer case, but rather, an electronic solenoid located near the center of the firewall above the engine. If this is the case, then engine vacuum will run to the solenoid, then from the solenoid down to the front axle actuator under the battery.

If you have the 3 button switch, you will have the mechanical vacuum switch on the transfer case. Engine vacuum will run down to the vacuum switch on the transfer case, then back up to the vacuum actuator under the battery.

The problem of the growling in the front axle has also been covered on this site many times. This is either a problem with the vacuum source, vacuum switch, vacuum line, actuator, cable, or the actual shift collar inside the front differential.

To diagnose further, we need to know what you have in terms of buttons on the 4wd system switch in the dash.

Try using some of the terms I have provided above to find other related threads.

 

hey guys i have a 2001 with the same growling in the front end that starts between 30 - 60 and goes away after i put it in 4x4 i have the 3 button switch on my dash if that helps... the button shows it going into 4x4 hi. but after i put it back in to 2 hi..a few seconds go by and you hear a loud clunk i feel it under the driver side. any ideas guys?? just trying to save some time and money..

 

No different than any other thread like this. You have a problem with the front axle engagement cable, collar, and/or return spring. Any one of those things, if not allowing the collar to disengage fully, will cause the noise when in 2HI. *EDIT* - check out THIS TECH ARTICLE.

 

Hey guys, this sounds like the same problem I am having. My question is how do I go about diagnosing the problems with the front axle engagement cable, collar, and/or return spring? Can someone please point me in the right direction. I have the three button system.
Thanks in advance,