I am trying to replace my TCM on my 98 Jimmy 4x4. I have everything apart.. the old one out, the front driveshaft cleared enough, but I cannot get the new one in. I have moved the transfer case with a crescent wrench and have found several detents where it seems to go, and I have it at the closest to the TCM as possible.

In the attached picture you can see the new (LEFT) and old TCM (RIGHT). The angles of the connection can be seen quite clearly. I put pencil marks on the new to help me align while I was under the vehicle.

I am really at the point where I am ready to take my chances and just move the new one to match the old. The old was left in the 2WD position. (default?)

any ideas why they are so different? I cannot move the transfer case any more.. its at the end of its stroke.

 

Any chance you could hook it up without installing it, then shift to 4Hi or 4Lo to get the right alignment?
Haven't replaced one yet to know exactly how to handle aligning one.

 

I seem to have read here or somewhere that you don't want to do that because the motor is expecting the resistance of the Transfer Case and the motor might slap or go too fast without it.

edit:
I gingerly tried to move the new TCM, but it does not want to budge. I briefly put the old one on and it goes on easy. I am putting the old back on and hooking everything but the axle back up, so see if I can get it to switch positions for the helluvit.

 

You couldn't move it because theres a lock solenoid that engages when the TCM shifts to a position.

I believe you can hook it up without it on the truck as long as you are connecting to the TCCM. I believe that what you read about was connecting it directly to 12 volts (Performing a bench test). But its only designed to move 120* so without the TCCM to stop it it will just keep turning and break.

I could be wrong though, I'm no 4x4 expert so I would wait for a conformation on that before I attempted it.

 

Well, I put the old TCM back on after disconnecting the battery for plenty of time.. and its working fine. There has to be an intermittent problem since i had fuses blowing from time to time and there was the transfer case error code stored.

If I can get more info on how to get the transfer case into postion I may try again. I am just proud that I was able to dig in that far.. and get the front axle all back on and the vehicle still works! although I am frozen through and trough now..

I could do it all again alot quicker.

Is there any way to get this transfer case into Neutral? (ie. towing , etc) I have a 3 button switch.. but nowhere does it mention Neutral.

I found this link on BlazerForum somewhere today. wish I had found it earlier.. would have helped me in getting the driveshaft off. very informative.. but didn't help with getting the case aligned to the new TCM.
http://www.zr2usa.com/mboard/index.p...rt=#entry97434

 

Did you try this step from the link....
Now you can remove the shift motor and test the Transfer case use a small crescent wrench on the shaft coming out of the T-case make sure ur Z is in neutral. You should be able to pull down on the wrench and make it shift; if it is in 2 wheel drive then the first click will be 4H and all the way down will be 4L
(IMG:http://i75.photobucket.com/albums/i3...2/DSC01275.jpg)

 

Yep, I found 3 locations when moving it with a wrench. I tried with the vehicle in Neutral. Never found a fourth location. Not sure what he means about all the way down.. 2 wheel drive seemed to be the location with the wrench mostly down on mine. (I could spin the front shaft freely).. the other 2 locations I could not.


Some other GM trucks must have a neutral for towing.. I don't believe this model does though.. I can find no documentation of it. I am wondering if the TCMs are generic and they are in the NEUTRAL location which this truck doesn't have. anyone have a clue about that crazy theory? now wondering if I had hooked it up to the cable left it hanging and shifted between the modes if the TCM would have ended up in the 2WD location where the other was.

I could find no useful information about the various detent locations on this transfer case on Google.

 

Idk about the 3 button cases but the 4 button (Auto4WD) you hold 2hi and 4hi together for like 5 seconds and it drops into neutral.

 

I tried that this afternoon, but nothing happened when I held those 2.

 

For the NV233 transfer case, I believe neutral is achieved by holding the 4HI and 4LO buttons.

As far as your encoder motor (not TCM) alignment problems, the proper way to handle it is to energize the brake circuit and then rotate the drive by hand. Some have plugged the encoder motor in and selected a desired position on the dash switch and had luck that way, but the motor can possibly overrun and destroy the encoder.

For more information on wiring, etc, have a look at the Tech Article (DIY) section for a post by error_401 or search for "NV233" or "NP233".