03awd ?

[Raw]

Just bought a used 03 awd Astro, has 124k miles. One of the previous owners removed the front drive shaft. Not sure why.
If the vans rear tires are in the air, with the van in neutral , engine not running, the output shaft on the transfer case turns in unison with the rear driveshaft, even if I put vice grips on the front output shaft, it seems to be locked with the rear drive shaft. Is this normal?

[Astrophysics]

Hi,

The 2003 AWD Astro single speed T case is the NV136. Also known as np136.

It uses Special fluid called GM Autotrac. II

It is electrically activated by TCCM. T case control module when wheel slip is detected, etc.''

You could try to un plug the AWD fuse in the fuse box under the hood.'

But, it could be that t case is damaged. But that could be a good thing. You could install a np 236 replacement t case which has a 2 speed t case and allows you to select 2 hi, 4 auto, 4 hi and 4 Lo.
Or you could install a np231 or np233 2 speed (aka has low range). T case.

See other write ups on forum.

AP

[Raw]

Thanks for the reply. I did unplug the fuse , but it is still 'locked' as in awd mode all the time.
Since the van will never see off road and or snow in my area, in the name of fuel mileage, would or is it possible to dissemble the workings of the transfer case innards to free up any parasitic drag on the drive train.?

[Astrophysics]

Hi,

It would probably be best to fix the Astro. The AWD is a great feature. You can get a rebuilt nv136 t case for about $500 or $300 used or one from Pic your part for $125 and install it yourself. The front axle on AWD is always engaged and it is a good system for safety in rain or snow.
Look at prices at on line transfer case.com etc.

The mileage of AWD is a bit lower than 2WD because the extra weight of t case + front differential + axles and front drive shaft etc adds about 200 lbs to vehicle.
The AWD has torsion bar front springs which are great.
get a nv136

[Captn. Crunch]

The np136 is a single speed electronicly controlled clutch actuated transfer case. Torque is transferred thru the case via a clutch pack. This clutch pack is designed with a preload that will transfer a small amount of torque forward to keep the front prop shaft spinning while the vehicle is in motion. The reason for this is once the computer senses wheel slip thu the speed sensors, the tccm signals the encoder motor on the t case to go active. It applies pressure to the clutch pack forming a solid connection. With the preload and the front prop shaft already spinning, the front diff receives power in .065 of a second. There is no noticeable lag time.
There are a couple of reasons why the P.O. pulled the shaft. Maybe he was trying to save fuel or there was something wrong with the system. Put it back in and see what happens. Any issues will have been documented along with how to fix it

[Raw]

Thanks for the info. But evidentially the transfer case is locked, or I should be able to turn the drive shaft with out the transfer case output shaft turning also.

[Captn. Crunch]

Thanks for the info. But evidentially the transfer case is locked, or I should be able to turn the drive shaft with out the transfer case output shaft turning also.

The case is designed that way. If the rear shaft spins-the front shaft spins

[Raw]

I would think the transfer case would only spin the front output shaft when it detects slip at the rear.
As mine exhibits signs of full time awd...

[Herbie]

I would think the transfer case would only spin the front output shaft when it detects slip at the rear.
As mine exhibits signs of full time awd...

See Captain Crunch's earlier post - there's a bit of preload in the computer-controlled clutch-pack. It's normal. This is pretty tough to test in the real world because you're not introducing loads. Short of putting the van on a roller table or finding a place to put only certain wheels on ice/sand, it's tough to get a concrete grasp on what's happening because everything is so dynamic. The TCU, under normal operation is making adjustments literally dozens of times per second. (It's sampling literally hundreds of times a second, but the clutch-pack can only react so fast since the shift motor takes time to turn.)

As above, highly recommend you return everything to "as installed" condition - install front driveshaft, insert AWD fuse, check the fluid levels, and give it a test drive. You may find that all is well. If you have problems from there, diagnosis is a lot simpler than taking random guesses based on half information. Believe me - I went down a very stupidly expensive path of swapping out all sorts of components before I finally figured out that I just had a bad u-joint in the front driveshaft that was knocking. $50 ebay replacement driveshaft later, all was well.

[Snowgeek]

I will mention that have a great condition np136 t-case just sitting in my garage if you happen to be near Boise, Id.

With that said, i think Truly I would do as others have stated get everything back in and start from there.

Ryan

[Captn. Crunch]

Since the van will never see off road and or snow in my area, in the name of fuel mileage, would or is it possible to dissemble the workings of the transfer case innards to free up any parasitic drag on the drive train.?

You could maybe probably don’t know for sure never heard of it being done before but ya drop the tc and open it up. Remove the chain and put it all back together. Leave the front prop shaft out as well. That should eliminate about as many of the spinny parts as you can.
Maybe u want to look at putting a rwd tranny in it and get rid of the t case all together.