Simple, FREE solution to AWD "crow hopping"

[jhenry999]

My wife's full-time AWD '05 Buick Rainier,(Trailblazer's cousin) , 94,000 miles, started skidding wheels and grabbing/hopping on slow, tight turns as if it was a 4-WD with the selector switch stuck in 4WD Low.(AWDs don't have selector switches- they are "on" all the time but only engage with a clutch in the transfer case when needed.)
I did all the usual things: changed transfer case fluid
(50,000 miles overdue) changed fluid on both front and rear diff's, all new set of tires (which it needed) checked out actuator motor/encoder on transfer case and TCCModule in dash. Sometimes the AWD "unstuck" but the next day it would get grabby again. AAMCO said new transfer case: $2.500. CHEVY dealer said rebuild transfer case $2,000 - ?. The funny thing is...it wasn't throwing ANY codes. The CHEVY SERVICE MANAGER said perhaps the bands/gears were sticking because they were damaged during the overdue fluid change period and the material was worn off and they were sticking together instead of sliding, and only getting inside it would tell. After explaining that I didn't have thou$and$ to spend on a fishing expedition to see what we could find, he said, "why don't you just remove the encoder motor and make it a 2-wheel drive? The rear wheels would basically just go along for the ride."" Long story short - IT WORKED! Unplugged the encoder motor, removed 4 bolts and pulled the motor off, pulled the #8 fuse and that's it! Took 15 minutes. No cost! These cars came in a rear-wheel drive and an AWD version. Mine is now a FRONT-WHEEL DRIVE Buick Rainier....perhaps the ONLY one in existence!

 

[Mounce]

Wonder how long the front driveline will last doing all of the work like that. Neat fix but I fear that you're dancing with the devil. I am subject to being wrong though so maybe it'll work just fine.

 

[Tiggerr]

I believe you are now a rwd rainier..the awd is rear biased and only engaged the front as needed I'm pretty sure. You could actually remove the whole front driveline if you were so inclined. Axles, diff, all of it.

I know some of the folks over at TBSSowners do exactly that and get rid of awd all together

 

[Mounce]

I was thinking that also... The encoder motor either engages or disengages the front driveline, I don't see how removing it deactivates the rearend.

 

[Tiggerr]

I was thinking that also... The encoder motor either engages or disengages the front driveline, I don't see how removing it deactivates the rearend.

It wouldn't.

To the OP... You can get a Reman transfer case for about $1k at Rockauto.com Swap it yourself.
IF that's the problem. Haven't heard of too many going bad. Usually I see ppl have disconnect and encoder problems more. I wonder if the disconnect isn't disconnecting.

 

[Mooseman]

There is no front disconnect. The one that is there is a "dummy" one, always engaged. Front wheels are always turning the front differential and driveshaft.

Everybody's assumptions of the truck now being a 2 wheel rear drive without the encoder motor is correct. Rears are always engaged. Fronts only engage by the transfer case encoder motor when slippage on the rear wheels is detected and then disengages again shortly after.

From the description of the symptoms, sounds like you have a defective encoder motor and not letting the front wheels disengage. The proof is that as soon as you removed the motor, it disengaged. You can leave it like that if you want, no ill effects except the fronts won't engage.

When my rear differential self destructed, I tried to get the front wheels to stay engaged by engaging the AWD and pulling the fuse. Didn't work and it would eventually disengage on its own. The AWD encoder motor, compared to the 4x4 one, doesn't have a brake to hold it in whatever position its in (confirmed by electrical schematics). This is by design so that it slowly disengages after its no longer needed. Not a fan of this system, would prefer a real 4x4 system. This is just a half assed AWD.

 

[carshinebob]

Just some thoughts. If the T case was sticking, It would still be sticking with the encoder motor removed. I think more trouble shooting is going to be needed. ~BOB

 

[HARDTRAILZ]

My wife's full-time AWD '05 Buick Rainier,(Trailblazer's cousin) , 94,000 miles, started skidding wheels and grabbing/hopping on slow, tight turns as if it was a 4-WD with the selector switch stuck in 4WD Low.(AWDs don't have selector switches- they are "on" all the time but only engage with a clutch in the transfer case when needed.)
I did all the usual things: changed transfer case fluid
(50,000 miles overdue) changed fluid on both front and rear diff's, all new set of tires (which it needed) checked out actuator motor/encoder on transfer case and TCCModule in dash. Sometimes the AWD "unstuck" but the next day it would get grabby again. AAMCO said new transfer case: $2.500. CHEVY dealer said rebuild transfer case $2,000 - ?. The funny thing is...it wasn't throwing ANY codes. The CHEVY SERVICE MANAGER said perhaps the bands/gears were sticking because they were damaged during the overdue fluid change period and the material was worn off and they were sticking together instead of sliding, and only getting inside it would tell. After explaining that I didn't have thou$and$ to spend on a fishing expedition to see what we could find, he said, "why don't you just remove the encoder motor and make it a 2-wheel drive? The rear wheels would basically just go along for the ride."" Long story short - IT WORKED! Unplugged the encoder motor, removed 4 bolts and pulled the motor off, pulled the #8 fuse and that's it! Took 15 minutes. No cost! These cars came in a rear-wheel drive and an AWD version. Mine is now a FRONT-WHEEL DRIVE Buick Rainier....perhaps the ONLY one in existence!

Never go back to where that idiot is a manager again. Holy fail batman.

You do not have a front wheel drive, you have a rear wheel drive. Pull the rear driveshaft and the truck will not move...

 

[Tiggerr]

Never go back to where that idiot is a manager again. Holy fail batman.

You do not have a front wheel drive, you have a rear wheel drive. Pull the rear driveshaft and the truck will not move...

That's pretty bad information even from a stealership! The local trans shop I would expect them to try to sell you a t-case. But for the Chevy house not to know how these work as many of them that are out there? Wow

 

[HARDTRAILZ]

Symptom crow hop...fix = disconnect rear. WTF It does not even make sense. Then thinking the encoder would disconnect the rear. WTFx2


FYI: OP-- There is NO full time AWD in this platform. You are right in they only engage the front when needed via the transfer case. The "disco" has a sleeve instead of a fork for engagement/disengagement.

 

[TequilaWarrior]

Just saw this - the TSB for crow hop actually calls for 2x tcase fluid change.... Change it once - DRIVE it - Change it AGAIN. I got my Bravada from a Ford dealership who knew NOTHING about this platform. When I came back with crowhop under my 30 day warranty they shrugged and sent it down to a Chevy dealership. I got it back with a note tucked under the visor - "Drive for xxx miles and return for second tcase fluid change." I don't remember how many miles it said, but with my work schedule I probably put 100+ miles on it before I got it back to the dealership. After the second fluid change - I've had no problems with AWD whatsoever and it's been just shy of 4 years. In fact, it's (over)due for the 150,000 mile service....

 

[Wooluf1952]

That's good to know. And for less than $20 in fluid, worth trying.

 

[24v 4.2]

Symptom crow hop...fix = disconnect rear. WTF It does not even make sense. Then thinking the encoder would disconnect the rear. WTFx2


FYI: OP-- There is NO full time AWD in this platform. You are right in they only engage the front when needed via the transfer case. The "disco" has a sleeve instead of a fork for engagement/disengagement.

The SS/Aero is full time AWD. It is a torsen unit.

There are 3 separate awd/4wd setups.

The non Aero Saabs and non SS AWD's are part time.

 

[HARDTRAILZ]

Interesting. Could make for upgrade for some then.

 

[Pepdidmn]

Having trouble with my 2006 rainier awd cxl, pretty sure it's the encoder motor. But, where the heck is the thing? Supposed to be drivers side and easily accessible in front of floor board but I can't find it. Removed the skid plate but no dice anyone have the schematic for the v8? I pulled the fuse and it's fine with it out just no front drive, had it at dealer for recall and asked them to flash the tc, they said no need its the encoder motor and shockingly enough didn't charge me! 138k and my daily driver to the train so not a huge issue but would like to fix it which I could do if I could just find it! Thx

 

[Mooseman]

How to change Transfer Case Encoder Motor

 

[Pepdidmn]

Thanks, I'll look again this weekend!

 

[Pepdidmn]

Well crap, new motor is on, same symptoms, time to change the transfer case oil. If that doesn't work I'm back to pulling the fuse and have a rear wheel drive Buick. not worth investing in a rebuilt transfer case and I don't have the time to put it in...……. Oh well good enough to get me back and forth to the train just need to take my time on snowy days or put the fuse back in for the 3 mile drive

 

[Mooseman]

What are your symptoms?

 

[Pepdidmn]

between 20-40 I get intermittent engage/disengage of the front wheels with a whine. Over 40-45 tends to go away and be fine, when I slow back down to a stop no issues as it comes back down through the gears but when I start back up same thing happens. Won't do it as bad on hard acceleration. Had it into the dealer for a recall last week and I had asked them to reflash the TC. When I went to pick it up they hadn't done it since they had the tech look at it quickly and said that wasn't the problem, it was TC encoder motor. Surprisingly enough they didn't charge me for the 'diagnostic'. If I pull the fuse on the TC no symptoms. There are no codes, nothing else is wrong. It all started when I had new front tires put on a month or so ago. At the same time I started getting ignition noise in the rear speakers which lead me to think it was the encoder motor going bad. Transmission shop couldn't figure it out and suggested new TC but the car isn't worth it and besides I enjoy the fun of trying to troubleshoot it

 

[Mooseman]

You do have the same size tires front and rear? Or the size difference is enough to make it think it's slipping the rear wheels.

 

[Pepdidmn]

Yep checked that as soon as it started doing it. Wonder if I inflate the rears a bit if if will stop, something to try in am.

 

[Pepdidmn]

So here's the morning update
Inflated rear (older tires) to 38 psi and left the front at 32 - maybe it got a little better
deflated rear tires to 28 and inflated front to 38 - much much worse
reinflated rear to 39 and deflated front to 29 - TBD will drive again this afternoon, have a real job to do for a while!

And also picked up two quarters of transfer fluid to change just for fun since to my knowledge it's never been done. Starting to wonder if there's a speed sensor that went bad or the TCCM is messed up. I've already taken off the battery lead to reset the computer and since I've pulled the TC fuse a few times I'd think that would 'jolt' the TCCM a bit. Now this is turning into a bit of a quest!

 

[C-ya]

I would get two new back tires before the fronts wear too much. The system is doing what it is supposed to do. Most AWD systems advise against any more than 2/32" of difference in tread depth to avoid AWD issues due to diameter/circumference issues as that changes the "speed" of each tire. The system is monitoring that speed and determining what is slipping when and that is used to engage the transfer case as required.

 

[Pepdidmn]

Yeah understand all of that and the intellectual side of my brain says "if the problem started when you put new fronts on, that's likely the issue". was trying to avoid that since the rears are not all that worn and different manufacturer. I just hate trying to keep throwing parts at it and nothing gets better. I keep saying 'this is the last thing I'll do and then I'll pull the fuse'. I pull the fuse, the 4wd light thingy lights up, I look at it and it gets on my nerves and then I say "ok I'll try one more thing". guess I'm a little OCD. New rears here I come I suppose!

 

[C-ya]

I hear ya. That is one thing I really considered when getting an AWD or 4WD vehicle - 4 tires at once. But, I have never not bought 4 new tires at once, so I think it won't ever be a problem. Keep 'em rotated and hope you don't destroy one in between changes. That would suck - get 20K miles into a set of tires and damage one beyond repair and then be stuck buying 4 new tires.

 

[Mooseman]

This part-time AWD, and the A4WD setting on the 4x4 trucks, is totally lame as opposed to a full time AWD. Only engages the front wheels when rear slip (or speed difference) is detected and bangs in the front wheels. One member actually changed his to a 4x4 transfer case that is fully switchable and functional.

 

[Pepdidmn]

Success, two new rears and all is good, what a wild goose chase. Thanks for the help/advice, up next this weekend new tie rods and may as well change tc fluid.

 

[Mooseman]

Incredible that something as stupid as a slight tire diameter difference would do that but like I said, lame system. Glad you got it sorted out.