02 Bravada Transfer case problems

[Andy17]

I have been reading up on this issue and still have questions. It started out being locked in 4wd. I did some research and drained and replaced the tc fluid (blue stuff) and encoder motor. This worked for about 3 days! It had locked up again. I took the encoderr motor out took it apart and found the gears broken on both encoder motors the new and old. I waited a couple of days driving with it out of the truck and the light came on this was expected. I was letting the fluid work it stuff and had to order a new motor. Installed new motor this time it worked about a week maybe. The same thing happened again it locked up in 4wd. I took the motor out and yes gears broken again. I have since found a post about the reprogram after install of encoder motor of the tccm.
I took the car to a chevy dealer to let them figure it out. I went thru the long version of what I had found and done at this point. Got the call it was ready to pick up they had done the other stuff I wanted done (shocks and front end alienment) and reported that the awd was working perfect. I tried to explain again I had pulled the gears out of encoder so I could drive it and he said their most experenced tech said he checked it fully and it worked! I paid and left! (no help from him!)
02 bravada
NP 126
120000 miles (still like the car and great awd when working)
So here are some of my questions.

#1 Could the lack of reprograming after encoder motor install be causing this problem?

#2 I have also read the fluid needs to be repalced after 100miles before replcacing encoder or activation of encoder (pull fuse until second change)

#3 What should I do change fluid twice then reinstall a new encoder motor? And get a reprogram before or at same time as new encoder?

#4 Should I replace entire assy transfer case (do you think its bad), encoder motor and tccm? (I really don't think so)

Thank you

Andy

[Chris Stewart]

The dealer said the AWD operated normal after you took the encoder gear out?

[Andy17]

YES they did!! I had taken the plantary gears out of the encoder motor assy explained this to him and then he said again his most experenced tech checked it out and it work "perfectly".

Does anyone have any suggestions?

[gmtech1]

There are a few bullitens out there to replace the encoder sensor and reprogram the tccm after replacement. This is a AWD transfer case, so the ft prop shaft will turn while driving. The tccm moniters the ft and rear prop shaft speed, when slippage is detected it uses the encoder motor to appliy a clutch pack in the t/case for the ft prop shaft. Then release the clutch when no slippage is detected. I'm not sure why the gears are breaking in the motor. Are all your tires the same size? all have good tread? These factors will cause major issues with the transfer case.

[Andy17]

All tires are the same and only about 25% wore now. They were almost new when the problem first occured. I also changed the fluid in the case when I did the first motor change out. I haven't or didn't change fluid again. I'm not sure why the gears are breaking either but its expensive to keep throwing motors on it to try to see why. I was hoping someone had info on the problem. Maybe the reprogram would do the trick but again really don't want to loose a couple hundred on a motor. I was thinking maybe the motor was trying to go back to netrual or not engaged and was binding because it was going too far back. Or the opposite moving to lock futher than the transfer case shaft would travel and breaking the gears. Hope I made that understandable.

[gmtech1]

I haven't heard of the condition you are having before. I'm sure it's not a fluid problem. It just about has to be something in the t/case.

[Andy17]

you think I should bit the bullet and get a rebuilt TC

[gmtech1]

Unless you can find someone around there that'll disassemble and inspect yours for a fair price, it may be more cost effective to replace it. I would want to know what is wrong inside yours first though. Call around a get some estimates, or search the net or get a manual for procedure and do it yourself.

[Andy17]

Anyone else have suggestions? Been here before?
Could the shaft coming out of the transfer case be kicking back against teh motor assy causing this motor assy gear to break? Bad clutch pack in the transfer case doesn't seem like it would do it not having this thing apart before I have no idea. One rebuilder I have spoken with said transfer case could not cause this and that is why I am searching again for answers. Any help would be greatly appreciated!

[Andy17]

Any suggestions on a good place to get a reman transfer case?

[Chris Stewart]

Here's something but going to need to ID your 2002 transfer case,

http://www.drivetrain.com/parts_cata...sfer_case.html

Ok, it's a computer controlled NP-136 transfer case.
The above site shows a GM136, you might check to see if they're the same.

[Andy17]

I know this is old but I thought a update would help someone else...
I was about to put a transfer case in but decided to take to another dealership first to give another tech a chance to find problem and just make sure that was the problem. Well it was a good choice for me. The tech came out and got all info and in about 30 min. he came back out said I needed a encoder motor and tccm flash at the same time! I let him to it and have been trouble free ever since!! Come to find out when you replace the encoder you must hook up the truck to a GM computer for a flash for it to index properly.

[Chris Stewart]

Thanks for the update Andy!
This will help others.

[ShadeTreeJack]

I have a 98 with the same, or similar issue; stuck in AWD. I have removed the encoder/motor/actuator assembly and attempted to turn the front output. It would not turn. ( rear wheels on the ground). I assumed the default would be 2WD, but from reading the posts, it appears that 4WD is default. Can anyone confirm? I have a used T-case ready for me to pick-up on the way home tonight.

[Chris Stewart]

Check this out,

http://www.automotiveforums.com/vbul...d.php?t=656997