AWD question and diagnosis

[j-bone]

Hello again , i'm having a but of and issue with my mother 06rainier v8 AWD .
at low speed turns the front end jumps and there is under steer ( front axle engaged )
I have it in the garage with the front end off the ground if i spin one wheel the opposite side spins the opposite direction typical of an engaged axle and the drive shaft is engaged to the transfer case.
should the front diff be disengaged normally ?
want to confirm that there is a problem here before proceeding further , there are no warning lights on the dash but I haven't done a complete scan of all system yet.
if it worth mentioning i need to replace the steering angle sensor for an intermittent code .
also there was a dash message something about the drive train cant recall the exact message but it was separate from the steering angle sensor.

 

[j-bone]

After looking at this more turns out I was thinking it was the same set up as the 4wd front axle with a disconnect in the front turns out there isn't.
is there any way for us home gamers to test the transftercase shift motor?
Ill change the fluid and see if anything changes.

 

[Mooseman]

The front axles are always engaged on the AWD trucks. The disconnect is basically a fake and always connected. So it's normal for your front driveshaft to always be turning.

It sounds like the transfer case is always engaged. The way it's supposed to work is that when it senses rear wheel slip, it will engage the front wheels and then slowly disengage again. Could be the encoder motor is stuck. Remove it and see if the transfer case disengages. If it doesn't, then something is up with the transfer case.

Also check the condition and level of the fluid. Should be changed every 50k miles.

Edit: you replied while I was typing this

 

[j-bone]

will do im trying to get the snap on computer and see if i can actuate the motor with out getting the dealer involved .
the awd takes the Auto-Trak II fluid correct ?

 

[freddyboy61]

Yes, AutoTrak II for transfer case fluid.

 

[j-bone]

I scanned and read the t-case vales and the encoder motor supply voltage is 5.09v
but the encoder return voltage is 3.69v
I'm guessing these should have the same values ?
I didn't make it to napa to get the fluid so she will stay parked till monday .

 

[Mooseman]

Don't have a clue for the voltages. I thoight it ran on 12v. It could also be the module.

 

[j-bone]

https://drive.google.com/file/d/0B1veA5xlnfoFVUw0NVhqV3h6X2M/view?usp=sharing
here is the screen shot.
I plan on pulling the motor tomorrow , can i manually " shift " the transfer case with it out to make sure no hard parts are damaged ?
thinking back a few months I got a call from my mother saying the car was very jerky and wouldn't move easily she pulled back in the driveway and when I took it out later that day every thing was fine but shortly after that she complained about jerking on sharp turns . Hope nothing in the t-case was damaged ...

 

[C-ya]

If it is the encoder motor, you should feel the release when you pull it out. Hang it up with a zip tie or the like. You'll know just by pulling forward with the steering wheel turned. If it is not the encoder motor, changing the fluid (may take a time or two) should help it if it hasn't been neglected long.

 

[j-bone]

just drained the fluid and there is some metallic shimmer to it no big flakes or chunks of friction materiel and its more purple then blue my understanding is its a blue fluid ? I did spill some on the floor and it pretty clear still and the level was correct.
looked the the service history and it was changed about 30k miles ago but before that there is no record of it, the transmission was replaced don't know if a fluid change for the t-case is normal when removing it or not .
120k on the car now .

 

[Mooseman]

The fluid should be blue. Change it and see if it helps. Try without the encoder motor to see if the TC unlocks without it.

 

[j-bone]

Ill get the fluid tomorrow and try.
pulled the motor trying to find bench test information but cant find any?
the shift shaft moves about an 1/8 of a turn freely havent tried to move it any further yet with a pair of pliers. not sure whats normal for the t-case .
the manuals for download here have no information on the transmission or t-case...?

 

[j-bone]

https://drive.google.com/file/d/0B1veA5xlnfoFdWcxYWdXR2xjMWc/view?usp=sharing
with the motor on the shaft i have to rotate it clockwise to get the holes to line up .
the front drive shaft now spins free from the transfer case. so looks like a failed motor ?
any change its a bad speed sensor or would that throw a code?

 

[C-ya]

I would imagine a bad speed sensor could cause the encoder motor (via the TCCM logic) to engage drive to the front end. But, I would think a bad speed sensor would cause a code to set. Not sure what the parameters are for it but I would think that if engaging the front end to correct a speed imbalance that never does correct it, a code should be set.

That's my uneducated $0.02, not adjusted for inflation and worth exactly what you paid for it.

 

[j-bone]

I would imagine a bad speed sensor could cause the encoder motor (via the TCCM logic) to engage drive to the front end. But, I would think a bad speed sensor would cause a code to set. Not sure what the parameters are for it but I would think that if engaging the front end to correct a speed imbalance that never does correct it, a code should be set.

That's my uneducated $0.02, not adjusted for inflation and worth exactly what you paid for it.

That's the way i see it as well...
well I ordered a new motor and decided to tear the old one apart to have a look see and found the issue,
a few of the planetary gears a missing teeth.
https://drive.google.com/file/d/0B1veA5xlnfoFRDRydVlPczhaRGc/view?usp=sharing
https://drive.google.com/file/d/0B1veA5xlnfoFXzh1T1ZBT3NNX28/view?usp=sharing

 

[Mooseman]

Please don't tell me you got Dorman?

 

[C-ya]

Yep, looks like those gears need to see the dentist! Or the round file.

Like @Mooseman says, if you got a Dorman and it fixes it, go ahead and get an OEM one so when the Dorman fails, you are ready.

 

[j-bone]

Please don't tell me you got Dorman?

no sir , I ordered the acdelco one .
I learned my lesson with dorman parts too many times.
I'm guessing most failures of these units are in the planetary not the motor, all the parts are made from powered metal , I plan on greasing the heck out of the new one before installation.

 

[j-bone]

Just wanted to follow up , I left the old motor off the car until the new one came in and besides having a dash light on it drove fine .
The new one arrived yesterday and when I went to put grease in it there wasn't any assembly grease which was weird maybe there is a reason for it or it's just engineered to fail ?
for those of you who care to grease your's the unit comes with a plastic piece that times the gear to the encoder (the motor isn't encoded the final drive gear is) keep it in place until you go to install it . remove the motor and thrust washer , them the first planetary gear ( four small outer gears and the plate ) take a grease gun with a needed attachment and stick it down the side of the gears and grease all 4 planetary s, you can remove the plastic piece and turn the gear an 1/8 of a turn each way to get the grease spread around then reinstall it then the final planetary thrust washer and motor. I added grease anyways and installed it tested it out and it locks and unlocks fine.
Another problem was the new unit didn't come with the dowels installed so you need to remove them from your old unit.

 

[Mooseman]

So you saying that there was no grease inside the encorder motor's gear case? How would you be able to see this without opening it? Last time I looked at one, it's sealed.

 

[j-bone]

The motor has two torx screws (t25 i believe ) take thoes out and pull the motor straight out do not twist there are two electrical connections . Now your in to the gear case, i'f you pull the motor out of the metal housing by teisting the plastic flange and pulling you can check the amateur and replace the brushes if needed .

https://drive.google.com/file/d/0B1veA5xlnfoFRVhjXy1EanVxVmM/view?usp=sharing

https://drive.google.com/file/d/0B1veA5xlnfoFUWFZTE9QRl9IMDA/view?usp=sharing

https://drive.google.com/file/d/0B1veA5xlnfoFOVcwQmhCMGIyQkE/view?usp=sharing

 

[Mooseman]

Ah, but did you take the new motor apart?

 

[j-bone]

Ah, but did you take the new motor apart?

yes i did , still have the old one supplier didn't tell me where to send the core ....