I have a 1994 Chevy S-10 Blazer with the Push Button 4WD 4.3 V6 "w" VIN. I was having problems with it engaging into 4WD, so I replaced the Transfer Case Shift Motor that is bolted up to the transfer case. Now the Blazer shifts into 4WD with no problem, but will not shift back out of 4WD into 2WD. With it in neutral it will shift in 4WD LOW and back up the 4WD HI with out a problem like is it suppose to. The problem that I hear was this. I would push the button to go from 4WD to 2WD and I can here the Transfer Case Shift Motor turn (2wd), pause and turn (4WD), and turn (2WD), then another pause and turn back to 4WD. As the Transfer Case Shift Motor pauses the first time, I can pull the fuse and it is in 2wd. I put the fuse back in and it will stay in 2WD. Press the 4WD again, it goes right in to 4WD, then try back to 2WD and it goes through the same steps as described above. So I thought that it was the Transfer Case Control Module (TCCM) (GM Part # 15673674). I just gone one in installed it and the exact same thing happens. So I am at a complete loss. BTW I HATE push button 4WD[:@].

I did the ALDL Check, the computer connector under the dash and I grounded the A & B Terminals and the only code that came up was the 12 Code. So that did not tell me anything. So right now I have the engine computer and the TCCM just hanging under the dash trying to determine the best option to fix this. Could it be the Switch on the Dash. Or could it be something with the Mickey Mouse vacuum hub lock system under the battery? I heard where the vacuum hub lock systemcan cause it not to shift in to 4WD but I have not seen where it would not let you shift out of it. So I am open to suggestions!!! HELP!!!!


I have attached two pictures of the TCCM for the 1992 - 1994 Blazer so some of you will know what one looks like.

 

When you replaced the encoder motor, did you replace it with a new one?

Have you tried seeing if the front axle was still engaged?

 

The answer is yes on both accounts. The front Axle is still engaged and the TCCM was replaced with a new one.....

 

From your first message, I read that you had replaced the TCCM with a new one, but it was not clear if you had replaced the encoder motor (on the transmission) with a new unit.

Also, is the front axle still engaged when you are in 2wd (after removing and reinstalling the fuse)?

 

I also replaced the Encoder Motor with a new rebuilt one. As for the front axle sill beingengaged, I did not go and check to see if I could spin either of the knuckles of the axle. I will have to give that a shot just to make sure that hubs are either in or out after I pull the fuse.... What are youthinking it could be?

 

I have done some more diagonis work here. I wanted to see if there were problems with the TCCM that I just replaced, soon the ALDL plugI jumpered terminals A and J.


NOTE: The ALDL is the same plug that you would use to plug in a scan tool. When you find it and you’re looking strait at the 12 terminals “A “would be on the top row to the far right, ”J” would be third from the left on the bottom row. Take a jumper wire, paper clip anything and connect A and J, turn the ignition to the run position. There will be about 3 second delay and then the 4X4 light may flash if there is a code present. There are only four codes available, numbering 1 to 4.

So when I did this, I have a one flash code. Now what does that mean?