My 02 s-10 ls blazer is acting up on me, which it prolly should with 140k on it. The 2 wheel hi button is glowing bright but lying to me. Sorta... There isnt any power going to the front tires but the front axel is locked up in 4 wheel, makes for a crappy ride and i know its doing harm. I can shift it into 4hi and low and it works fine but it never fully disengages. Any ideas as to what it could be? I was told there are two sensors on the transfer case and one might be bad? Does anyone know which sensor it may be. The dealership wants me to but a new trnasfer case but i know that is not needed. I appreciate any help, this site is great, too bad i had to find it under these circumstances. Rob

 

you could be having troubles with the encoder motor. This is the one that shifts the transfer case into 4hi/4lo. There is also a vacuum switch and cable under the battery box that controls 2hi/4hi, if the problem is that the front axle is not disengaging then it could be the vacuum switch, the cable to the front diff. or the actuator inside the front diff. Sometimes the cable will become rusted and hard to move you should remove the cable and spray cable lube down the sheath and see if that helps. After that you could move to the encoder motor and then maybe the TCCM (TransferCaseControlModule). Those items can be checked with a DVM to see if they are electrically functioning. Then if you find that one of them is bad you can replace that part... I don't think that your transfer case is bad unless you just beat it to death...

 

I appreciate the quick reply. Im going to look at it today after work, hopefully it is a quick fix. Thanks a lot.

 

This is definitely a stuck vacuum switch (the one that screws into the top of the transfercase..on the driver's side just above the encoder motor)!! When your t-case is shifted into 4wd (via the encoder motor) it pushes this switch up and applies vacuum to the front axle actuator (under the battery tray). When the t-case is shifted back into 2wd the switch returns to the open position and vacuum is vented out. Your switch is stuck closed and constantly routing vacuum to the front axle actuator....hence the front driveshaft is not turning and the 2wd button is lit..but the front axle is staying engauged. This switch is about $35.00 at the dealer, but I will sell you a new G.M. one shipped for $22.00 if you're interested let me know. Even if you don't want mine...this will DEFINITELY fix your problem! Keep us posted please!

 

Wow,
Coupe, that was a great answer, feels like you drew me a diagram, i will pass on the switch, the fleet mechanic at work will just charge it to the company. I will slap it in on the lift friday and be all set. Thanks a ton. Im getting to love this sight.

 

No problem man...that's why I'm here...Please let me know if that fixes it, but I'm pretty sure it will from what you describe.

 

I wanted to reply to this thread as I have a similar problem and after searching this is the closeet to it I could find. I have a 97 blazer with the 2hi/4hi/4lo on the switch and when I press the buttons it goes into 4wd just fine. It's when I'm not stopped and moving 30+ mph and I hit the2wd button, The axle dosen't disengage unless I totally stop the truck. after stopping, It disengages just fine. It did disengage the other day when I was moving after I went back to 2wd but it had a pretty big clunk. I was only going 25. Everytime I go back to 2wd and don't stop totally, The axle feels like it wants to go back to 2wd but it just never does. I do have a new transfer case switch. Thanks for the hlep. [sm=dontgetit.gif]