9-7X AWD not working, Tech 2 says "multiple motor control attempted"

[dkvasnicka]

OK, I'm creating a topic for my AWD problems first decribed here.

When I bought the truck in June AWD worked. Or at least I saw it working at the end of July when I had the car up in the air and saw front wheels engage. I considered AWD story closed and then at the end of august I changed the TC fluid for the peace of mind, only to find out there wasn't Auto-Trak II in there. But I had seen my AWD work before that so I wasn't afraid and just put a fresh fill of ATII in.

Now that winter came I've been in a few situations that I thought would not have been possible with only rear wheels (and an empty car and cargo area), the car is stable, predictable, handles much better than my previous front-engined FWD cars, fights for traction only momentarilly... So I thought that it was AWD and took it that it simply works. But then I went to a snowy parking lot and did a few test, introducing intensive slippage of the wheels etc... And I found out that AWD doesn't work. I even saw the SERVICE AWD light once, however how it doesn't work without any lights or messages.

So today I took it to a shop that does american cars here to hook it up to the all-seeing Tech 2. The mechanic tried to run the Automatic Transfer Case tests but every time he ran it the display just said "multiple motor control attempted" (and I believe it was presented as an error). If I understand it correctly that means that Tech 2 tried to move the encoder motor multiple times and failed. We then took it for a spin around their lot and to a small snowy road and watched the data from the TCCM as I was flooring it and loosing traction. The TCCM gets all the data, front+rear shaft RPM, slippage RPM, so the sensors work and TCCM does as well. There was also a value called "Clutch Pedal", which was always "Off" (or "No"?) - since there is no pedal it sounds a bit misleading. Does this relate to the clutch pack that is supposed to be actuated by the encoder motor?

My main question is of course whether I should first try to change the motor or whether the error message points to a problem inside the TC. As I mentioned in my post about the transfer case fluid, there was a different fluid and it also has a gasket sealant on it, i.e. was being worked on. But then again: I saw AWD kick in on at least one occasion and since then I haven't heard any bad sounds.

The problem is that the shop has Tech 2 and is able to work on GM cars but it was evident that they are more focused on Chrysler and Jeep cars (though they had an old Ford Explorer and a 6.0 Avalanche parked in their lot - what a beast!) and the mechanic wasn't very sure about what to deduce from all this...

 

[Mooseman]

Unfortunately, I didn't do anything with my Tech 2 and the AWD system so I can't advise and my 9-7x is sleeping for the winter.

Here's what I suggest. Remove the encoder motor, gently put on some locking pliers on the shifter stem, turn it to see if it moves, keep it in the locked position with a bungee cord. Take it for a drive. Even on dry asphalt, it should crow hop on sharp turns. On snow, it should spin the front tires. Basically, it should behave like a 4x4 in 4hi. If the TC works, then it's the encoder motor.

 

[dkvasnicka]

I've read it gazillion times that people verified that the motor is dead by doing this test, proving the motor is not able to turn into states it needs to. However what I don't know is whether this was it. Or whether this outcome is something wrong happening before the actual test actually began.
I could also take it off and just do battery test, trying to rotate the motor. It that fails I know I first need to replace it anyway before worrying about the TC. And trying to move the stem is a good idea as well (should move to the right to engage the clutch plates, right?)

Do we have some wiring diagram for the encoder motor? (haven't found it in the manuals section) Or is it a deprecated technique to try and play with it with 12V?

Weather sucks No garage, not going to take the motor off in sub-zero temps. And not going to pay ridiculous amounts of money to people for taking a few screws off...

 

[Mooseman]

Ask and ye shall receive

Yeah, with the AWD system, you can't command the motor to shift except with a Tech 2 or on a lift with 4 wheels off the ground. I have no idea which way it turns.

I don't know why, I thought you already replaced the encoder motor. Anyway, the schematic should help but if it looks bad, it probably is. Oh, and if you buy a new one, stay away from Dorman brand. Known to fail early.

 

[dkvasnicka]

Yeah, I've read about people buying a new EM after 6 months with Dorman... So are both Cardone and ACDelco better, even if remanufactured?

 

[Mooseman]

Cardone isn't any better in my opinion but because it's a rebuilt, it might be OK. ACDelco is the best but usually pricey.

 

[dkvasnicka]

BTW, if it ends up being a transfer case being FUBAR and not the enc. motor, is TC from a 2002 TB compatible? Were there any backwards-incompatible changes over the years?
I know 2002 is an old car but here in Europe I don't have much choice...

 

[Mooseman]

In one word, no. 9-7x is an AWD, TB is a 4x4. Totally different animals.

 

[dkvasnicka]

I know, but I somehow thought the TCs are the same/compatible and that AWD GMT360s can use the 4x4 and just not exploit it's full potential... nevermind. I guess the biggest incompatibility is the LO gears in 4x4 TC.
Thanks.

 

[dkvasnicka]

So when eBay sellers say a TC from TB or Envoy is compatible with the 9-7X they are wrong? Basically every TB TC ad on eBay says that...

 

[Mooseman]

I would definitely not rely on eBay listings for compatibility of parts. Most mechanical parts are compatible but certainly this one isn't. Sad part is I have a spare from a 9-7x. Problem would be shipping this beast over the Atlantic.

If your TC is borked, another option may be to order the parts and rebuild it yourself if you have the tools and skills. But before you get ahead of yourself, you need to confirm that it's not the encoder motor.

 

[dkvasnicka]

Yeah, I'm definitely waiting for the encoder motor, should arrive next week.
As far as rebuilding... well, I have no idea what would it take. It would also mean renting another car for some time because I don't have another.
If I had a really good writeup on how to tackle the specific problem (let's say, clutch plates need replacing?) then I think I could handle it. The problem is that I would find out the actual problem only after opening the TC and then I'd have to order parts & stuff... I don't know, seems like a PITA without a second car.

 

[dkvasnicka]

OK, so it's not the encoder motor

I raised all 4 corners today, put it in D, started spinning the back wheels and when I stepped on the gas a bit the fronts engaged... When I lifted my leg from the gas and let it just spin the back wheels, the front left stopped spinning but the front right kept spinning together with the rears - but it was possible to stop it by hand. I tried to "help" the left front a bit and it was apparent that it has some kind of torque going into it. I thought the front locks when AWD kicks in...? So is my front diff bad? Or the specific "disconnect" that the AWDs have?
Also, the SERVICE AWD light came on, basically as soon as I stepped on the gas to engage all 4 wheels. I tried to read the TCCM codes using information from this thread but it doesn't work for my car. When I had all 4 corners in the air at the end of July to test it I don't remember any light and I also remember to see all 4 wheels turn consistently.

I was doing both diff fluids and the TC fluid at the end of August. As you may remember the TC had a bad fluid in it, looked a bit like Dexron. Is it possible that the AutoTrakII I put in it somehow mixed with the remains of the old fluid and makes the TC not work? Should I try another fluid change?

Today I didn't have any weird sounds, I have no leaks.
Should I just disconnect the front shaft and call it a RWD?

 

[Mooseman]

That sucks the big one.

You have to read the codes while the light is on so that may be the reason you didn't get them. If you have a Bluetooth interface (ELM327), you could use Car Gauge Pro on Android to read all codes. Likely the codes won't help out much here anyway.

If it was the differential, you would know. When my rear diff grenaded, it made an awful grinding noise, had occasional snapping and popping and completely freewheeled. The oil would also have bit of metal in it.

I have a feeling that the wrong fluid burned up the internal clutches. As a hail Mary, you could try to go back to tranny fluid. Maybe the different friction modifiers in the fluid conditioned the clutches. Can't make it any worse.

Too bad it would cost so much to ship over there as I have a spare one here. Keep an eye open for one that's getting scrapped on your side of the pond.

 

[dkvasnicka]

That sucks the big one.

You have to read the codes while the light is on so that may be the reason you didn't get them. If you have a Bluetooth interface (ELM327), you could use Car Gauge Pro on Android to read all codes. Likely the codes won't help out much here anyway.

I did try to read them with the light still on. My son has an Android tablet as a fairy tales player so I may try to steal it for a while

If it was the differential, you would know. When my rear diff grenaded, it made an awful grinding noise, had occasional snapping and popping and completely freewheeled. The oil would also have bit of metal in it.

But what about the wheels not being locked together? What are the symptoms when the "permanently connected disconnect" fails on an AWD model? Would it cause some distinct noise? Undriveable?

I have a feeling that the wrong fluid burned up the internal clutches. As a hail Mary, you could try to go back to tranny fluid. Maybe the different friction modifiers in the fluid conditioned the clutches. Can't make it any worse.

That has't crossed my mind... will think about that. No idea what the previous fluid exactly was, though.

Too bad it would cost so much to ship over there as I have a spare one here. Keep an eye open for one that's getting scrapped on your side of the pond.

Actually, there is a delicious rarity for sale in CZ right now: a 2008 4.2 9-7X that basically hasn't been driven.... the dealer says it has like 100 km. Some unsold piece. I don't have money for it right now but wish I had

 

[Mooseman]

If you can lock the front driveshaft some way, lift the front end and then turn one wheel, the other should turn exactly the same amount in the opposite direction. If not, then the disconnect may be broken or the splines inside are stripped. It shouldn't but anything is possible. Anything is possible and I would investigate that first before condemning anything else.

 

[dkvasnicka]

Well, both Germany and Poland are "full" of TB/Envoy transfer cases... and of course all the ads say "9-7X" too. I found a few totalled 9-7Xs in Germany but TCs were not listed as available. Will have to setup some kind of eBay watchdog.
I just hope it's not much of a PITA to replace a TC. On first sight it seems to be relatively well accessible.

 

[dkvasnicka]

Actually, there are 2 9-7X transfer cases in Poland! Both go for almost $900! (and one of them isn't even willing to ship to CZ and is 7 hrs of drive away)

 

[Mooseman]

Maybe a family trip with a slight detour?

Is that $900US? Wow. I paid like $650CAD for an engine. Crazy!

 

[dkvasnicka]

Yep, 900 USD. Trailblazer-compatible TCs go lower, like 500 - 600 USD. These sellers probably know that the AWD TCs are unique and rare in Europe and price them accordingly...

I did a quick search for 4.2 TB engines in Poland... three, all of them > $1600

 

[Mooseman]

I see 2WD in your future

 

[dkvasnicka]

One more thing. They say some torque is always transmitted to the front, like 5 % or so. Isn't it possible that what I saw (wheels spinning with all 4 corners in the air) was that and that it's indeed the encoder motor, not being able to engage fully? Is the "residual" torque being sent to the front capable of doing this?
I already have a replacement encoder motor... so I'm thinking, maybe I could just try it, out of desperation After the front axle+shaft test you mentioned.

 

[Mooseman]

I don't think so. I'm thinking it's more slipping clutches when trying to engage but I could be wrong. Did you install the new motor yet?

 

[dkvasnicka]

Nope, that's why I'm thinking it's still an option. Should've probably made that clear earlier, sorry.

 

[Mooseman]

Well, get to it man!

 

[dkvasnicka]

Btw, the app profile for Car Gauge Pro in Google Play Store only mentions bluetooth ELM327 adapters. Do you have any idea whether it's really constrained to BT or whether it can work with WiFi adapters as well?

 

[Mooseman]

Sorry,don't have a clue. If that's what you have, I think there is a free version or you have 10 minutes to get a refund.

 

[dkvasnicka]

I still haven't gotten around to changing the transfer case motor... (weather, health, no need for AWD). However I just found out I could have a new 9-7X transfer case for $850 shipped. It's a lot of money (more than twice as much compared to used ones) but it has never been used and is from a Saab dealership here in Europe. Do you think it's worth the money (compared to, say, 2004 - 2005 used transfer cases for half the money)?
I mean, in case I find out it really is the TC.

 

[Mooseman]

Well, before spending any more money, change the TC motor. Then look at your options if needed.

 

[swede]

I raised all 4 corners today, put it in D, started spinning the back wheels and when I stepped on the gas a bit the fronts engaged... When I lifted my leg from the gas and let it just spin the back wheels, the front left stopped spinning but the front right kept spinning together with the rears - but it was possible to stop it by hand.

With no resistance on all 4 wheel it's normal for just one one of the front wheels to spin, there is NOT a limited slip or locking differential in your front axle. So only one front wheel is suppose to spin even if you are in the snow or ice, it's a 3 wheel drive not 4 haha. Also when you stopped the right front wheel did you see if the left started spinning? No guessing need 100% correct answer.

I tried to "help" the left front a bit and it was apparent that it has some kind of torque going into it. I thought the front locks when AWD kicks in...? So is my front diff bad? Or the specific "disconnect" that the AWDs have?

When you tried to help the left front did you see if the right was totally still or did the right wheel begun spinning again? Same here no guessing need 100% correct answer.

Also, the SERVICE AWD light came on, basically as soon as I stepped on the gas to engage all 4 wheels. I tried to read the TCCM codes using information from this thread but it doesn't work for my car.

Not unusual that the AWD light comes up when all 4 wheels are off the ground and you hit the throttle, has to do with no resistance on the wheels and readings from ABS sensors that all wheels not turning with the same speed. Didn't you say you had an Tech 2 or did I read it wrong? If you do have access to an Tech 2 you should be able to read the codes with it.

 

[dkvasnicka]

With no resistance on all 4 wheel it's normal for just one of the front wheels to spin, there is NOT a limited slip or locking differential in your front axle. So only one front wheel is suppose to spin even if you are in the snow or ice, it's a 3 wheel drive not 4 haha.

This goes contrary to all the information I've ever read about this type of AWD. AFAIK the front axle locks when engaged. That's why people crow-hop on dry pavement when their encoder motor fails and gets stuck in engaged position.
Every time I played with it with all corners in the air ALL the wheels were spinning. Last time the only difference was that I could stop a wheel with my hand, which IMHO means:

a) the TC motor is dead and what I saw was a residual power going to the front wheels even with the clutches disconnected
b) the motor is OK and the clutches are FUBAR

Not unusual that the AWD light comes up when all 4 wheels are off the ground and you hit the throttle, has to do with no resistance on the wheels and readings from ABS sensors that all wheels not turning with the same speed.

I don't remember seeing the AWD light when I first tried it with all 4 corners in the air (that was way back before I even changed the TC fluid, somewhen last summer). AFAIK the AWD light goes on when the TCCM engages the TC and both driveshafts still have different RPM -- which is not what is happening when all 4 corners in the air and when the AWD system is OK.

I'm really eager to finally change the motor so we can move forward with this, I hope weather and my free time finally come into alignment very soon...

 

[coolasice]

This goes contrary to all the information I've ever read about this type of AWD. AFAIK the front axle locks when engaged. That's why people crow-hop on dry pavement when their encoder motor fails and gets stuck in engaged position.

The front differential is still an open differential, not locked, if you stop one wheel from spinning all the power is transferred to the other. The reason you get crow hop when the encoder is stuck engaged is that the system is trying to turn all 4 tires at the same speed (being on pavement there is no slip).. when you turn the wheel the inner tires turn at a slower speed then the outer tires, but the engaged transfercase won't allow them to change speeds so they "hop" or slip on the dry pavement.

 

[dkvasnicka]

The reason you get crow hop when the encoder is stuck engaged is that the system is trying to turn all 4 tires at the same speed (being on pavement there is no slip).. when you turn the wheel the inner tires turn at a slower speed then the outer tires, but the engaged transfercase won't allow them to change speeds so they "hop" or slip on the dry pavement.

I admit I have problems seeing the difference between what you are saying and a plain simple open rear diff - which doesn't crow hop, obviously.
To me the fact that the TC still powers the front wheels does not imply crow-hopping if it's indeed still open as you say. If it's open then based on the core principle of a differential it should not hop. Where's the difference? You could as well say that an engaged transmission on a RWD causes crow hopping with a simple open diff, but that's obviously untrue.

What am I missing?

 

[swede]

What am I missing?

Knowledge is what you're missing!

Both drive shaft from TC turns with the same speed (front and rear) but front and rear differentials pinion gear do NOT turn the same speed due to that front and rear wheels don't turn with the same speed because they travel different distance when traveling in a turn (see video).

The small differential gears allows the left and right wheel to turn with different speeds inside the axle, but the drive shaft always turns with the same speed from gearbox or TC. So when you make a sharp turn the front difference gear revolution is to small or big to be able to maintain the same speed as the drive shaft from TC.
Result in craw hopping, you can make small turns and only feel some resistance but as soon as you turn the wheels to far it will come to a halt or start hopping.

 

[dkvasnicka]

Aaah, so it's kinda like a "center locker", right?

 

[coolasice]

Aaah, so it's kinda like a "center locker", right?

A fully engaged transfercase is a center locked transfercase.

 

[dkvasnicka]

Just changed the damn motor!

All 4 corners up, fronts engage, NO AWD light (only abs light and stabilitrak lights went on during our messing with the front wheels), when I stop one front tire with my hand the other one spins fast and cannot be stopped by hand. I think we have a winner!

Just one weird thing: during the test there was a periodic electric "vzzzzt!" sound coming from the transfer case every few seconds (dont remember ever hearing it before). I assume it's the motor but why is it doing this again and again? Is it because it engages, wheels spin roughly the same speed so it thinks it's OK, disengages and then finds out slippage is still here (i am in the air) and the cycle continues?

 

[dkvasnicka]

ok, so the abs and stabilitrak light are now on all the time! grrrr

OBD scanner shows no codes.

 

[dkvasnicka]

Havent driven it anywhere too far, just a few meters forward and back in my driveway to see if they come out when the car starts moving.
The ABS light only comes on when the car starts, the stabilitrak one doesn't even come off after system initialization.

My SWPS is slowly dying, but this is different. When it comes on due to the SWPS it's only when its cold and I havent seen it in months now.

could engaging the car in the air have damaged a wheel speed sensor? and do I need a Tech2 to read that?

 

[swede]

could engaging the car in the air have damaged a wheel speed sensor? and do I need a Tech2 to read that?

No ABS wheel speed sensor damage from running in the air, I would hook up Tech 2 to check and remove all DTC first before spending time online guessing anything.

The ABS light could come off if you drive it for more then a couple of meters, try go around the block first.