2002 Oldmobile Bravada Smart Trac Help!!!

[tmenna]

I bought a used Oldmobile Bravada on Friday and have noticed a tightness when I turn. I really am having a hard time describing it. It feels like it is in 4 low. I have changed the transfer case fluid. The AWD is working I am just not sure if it is disengaging. I am in the process of trouble shooting this issue. I have owned many four wheel drive suv's just not ones with the Smart Trac system. I have read all of the forums posted and was wondering if anyone has new imput with this topic. It is an awesome car!! Just very confused!!

[old_master]

GM has a new fluid for the Smart Trac system, it's blue in color and is supposed to take care of the issue you're experiencing. Sometimes requires changing the fluid again after 100 miles.

[tmenna]

Thanks I was told by a Trans shop that the clutches inside the transfer case may be binded together.. Is this possible? Also is there a way I could trouble shoot this and see if maybe it could be the ATC or something a little more affordable..I bought this SUV on a snowy day so I was unable to feel this binding on the test drive.

[83cutlass]

On the new body style 2002 Bravadas it almost always the encoder motor that has failed. There is a bulletin out:
#02-04-21-008A: Shudder, Rocking Motion, Binding, Feels Like Vehicle is Stuck in 4WD (Crow Hop) When Turning at Low Speeds (Replace Transfer Case Encoder sensor and Reprogram TCCM)
It describes changing the t-case fluid, replacing the sensor, and reprogramming the T-case module. My experience has shown its better to replace the whole encoder motor and not just the sensor.

[foreveryellow7]

Originally Posted by 83cutlass

On the new body style 2002 Bravadas it almost always the encoder motor that has failed. There is a bulletin out:
#02-04-21-008A: Shudder, Rocking Motion, Binding, Feels Like Vehicle is Stuck in 4WD (Crow Hop) When Turning at Low Speeds (Replace Transfer Case Encoder sensor and Reprogram TCCM)
It describes changing the t-case fluid, replacing the sensor, and reprogramming the T-case module. My experience has shown its better to replace the whole encoder motor and not just the sensor.

I have a 2001 Bravada that I purchased about 6 months ago. Pretty sure this is the same thing I have experienced. Actually, I thought at times like when pulling into a parking space, that I had lost the power steering. Mechanics have blown me off as a female driver who doesn't know what I'm talking about. Do you think this is the same as what you are talking about here?

[Chris Stewart]

Yes, sounds like the same thing.

[tmenna]

I took the Bravada back to the dealer I bought it from and he returned my check and took the car back. I took in an estimate to fix the Bravada and it was in the thousands. The clutches in the transfer case were completely welded together. The mechanic said it was so bad that it was impossible that the dealer was unaware of the problem. I loved the SUV but was fearful that it was going to be a cronic problem. When I test drove the car it was snowing outside and I was under the impression that the AWD was activated because of that. Should have thought differently. I was told by the trans man that most of the time the TCCM goes bad and people neglect to fix it, in result the damage to the transfer case is great and will be very costly.
Great SUV bad AWD design...proceed with caution when purchasing a GM with the Smart Trac system!!!

[83cutlass]

Originally Posted by tmenna

The mechanic said it was so bad that it was impossible that the dealer was unaware of the problem....
I was told by the trans man that most of the time the TCCM goes bad and people neglect to fix it, in result the damage to the transfer case is great and will be very costly.
Great SUV bad AWD design...proceed with caution when purchasing a GM with the Smart Trac system!!!

Believe what you want to believe but honestly the clutches welding together isn't really possible.
I've never seen a TCCM fail and I work in a large (former) Olds dealership.
Although I personally don't care for the Bravada AWD, I don't believe its a bad design.

[83cutlass]

Originally Posted by foreveryellow7

I have a 2001 Bravada that I purchased about 6 months ago. Pretty sure this is the same thing I have experienced. Actually, I thought at times like when pulling into a parking space, that I had lost the power steering. Mechanics have blown me off as a female driver who doesn't know what I'm talking about. Do you think this is the same as what you are talking about here?

Well not exactly, the 2001 is slightly different. The usual fix for crow hop in those is double t/case drain and refill (with the blue Autotrak GM fluid) with a 5 mile road test in between. Sometimes other things fail like the encoder motor or the clutches. But usually 90% are fixed with the double drain and refill. Ask the GM dealer to do a bulletin search and follow the service bulletin.

[NoBrake]

I have a 2000 bravada and I also is stuck in 4X4 mode -- I am not sure on a encoder motor / sensor on this year -- Is there one and How do I test it? I have changed my transfercase fluid out twice and it did help for a few days but I gave up on it since it does not last. I was just at Advanced Auto parts store today and they now sell the GM Fluid -- It is some Pennzoil brand. FYI

[83cutlass]

If the fluid change helps then you most likely don't have a problem with the encoder motor. Most like the clutches don't have enough clearance, either because of dirt/grime build-up or I also seen chunks of silcone sealer (used to seal the halves of the case together) in between the clutches. If that the case then its best to dissassemble the t/case, clean or replace the clutches and re-shim the clutch clearance. The factory set them up tighter then we do now.

[NoBrake]

Thanks for the info 83 !!!--- I am thinking about doing a triple gear oil change in like a 3 week period and if that dont work then I will drop the transfercase. And go with your idea. I have been searching for ideas for this problem for over a year. If I do a transfer case overhaul then I will post a new thread for spec's on what are the clutch clearance's -- My haynes manual does not go that far in depth. Hopefully you or someone will be able to help me then. Again thanks for the info

[tmenna]

That fluid change helped for a couple days. The former owner of the Olds let this problem persist for such a long time that it damaged the clutches in the transfer case. The dealer changed all the equipment that was listed. They reprogramed the computer and still the problem persisted. I even went as far as to check the tire size and pressure. Quite honestly I am limited in knowledge with trans equipment. Thanks for all your advice I hope that all is well. I ended up picking of a mint conditon 98 dodge ram.

Originally Posted by NoBrake

Thanks for the info 83 !!!--- I am thinking about doing a triple gear oil change in like a 3 week period and if that dont work then I will drop the transfercase. And go with your idea. I have been searching for ideas for this problem for over a year. If I do a transfer case overhaul then I will post a new thread for spec's on what are the clutch clearance's -- My haynes manual does not go that far in depth. Hopefully you or someone will be able to help me then. Again thanks for the info

[NoBrake]

thanks for your response Tmenna -- This is making me think that your vehicle problem was something other then the transfercase. Possibly mine could be the same thing. I changed the right front wheel bearing a month ago becouse of a loud noise coming from that area. After I changed the bearing the noise was gone and I was hoping at the time that wheel sensor was bad and was causing my transfer case problems. But it did not change anything other then the noise went away. Could my left side wheel bearing be bad and sensor not working and me not even notice it -- and if that is a yes -- would that have something to do with my transfercase being in 4x4?

[matt_o_70]

83Cutlass - Finally someone who has seen the inside of one of these things and dealership experience! I like what I am hearing!

I have got to say this has been my suspicion for some time.. That there is excessive drag common in this clutch pack setup..

I have a 2000 and the previous owner was given the run around by repair shops who really did not know what to do. so that it hopped and clicked like mad in a tight full stop when I test drove it.

I did fluid changes and that helped but there is still noticable drag anytime that the wheel are turned tightly. I suspect that my MPG is suffering somewhat as you really never feel that it is in 2WD. I do not know what the smart trac felt like new? should it feel like any other 2WD system when not engaged?

Before I do anything to the transfer case.. I would like to test the transfer case motor to see if it is part of the problem. Can I just test this off the vehicle with 12V? There is a warning about doing this - What is the concern?

Also I assume that the motor applies pressure to the clutch pack? to engage the transferr case? Can i manually check that the motor is retracting all the way? If so what is the disengaged position? Is there a measurement or a clock position?

Thanks,
Matt