# TREG w/Rear Diff: one stepper motor or two? Need definitive answer please



## noc (Feb 15, 2004)

Just back from dealer's latest attempt at fixing both scrubbing/binding and hill descent brake shop fault warning. I read on other posts that there may be two stepper motors in models with rear diff (one for the center diff lock and the other for the rear diff lock?). The suggestion was that to fix the hill descent brakeshop fault warning, replace the rear stepper. To fix the binding/scrubbing problem, replace the other stepper AND the transfer case control module. 
Here's what they did to mine: replace stepper motor and seal (SM says it was "the rear") Who the heck knows. The VW tech rep refused to authorize replacing the control module in spite of my printing out about 100 pages of posts telling him both must be replaced. Anyway, the binding seems better, but not 100% gone. I have no idea about the hill descent brakeshop fault as it was only intermittent to begin with. 
But my question is this: does anyone know definitively if a TREG with rear diff has one or two steppers? I don't want to sound like an idiot when I go back in again and tell them to replace "the other" stepper (and module) if there isn't another stepper to replace.


_Modified by noc at 12:04 AM 12-31-2004_


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## igster (Oct 6, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

I don't have the rear Diff lock... VW has replaced 4 stepper motors for me.. without a problem.. the last one was last week I have 35k....I thought I was free and clear of this... I ran for about 15k without any binding or grinding... good luck....you should hear no binding or grinding at all


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## TREGinginCO (Jan 4, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (igster)*

From everything I've read and been told - there is only ONE stepper motor on the TOUAREG and it's designed to move the gearing from HIGH to LOW.
The differential locks are electronic and there are one or two of them, depending on whether you have center and rear lockable differential.
That help?


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## irbrenda (Oct 9, 2000)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

Like you, I printed everything out for them. They read everything but said they are guided by the advice of the higher ups.
So, don't feel bad about them not replacing the transfer case control module. They absolutely refused to replace mine and Mark's. ( I think he had 2 steppers done so far) and no, it's not 100% perfect. For me it's 95% and I can still feel slight binding when turning slowly to the right. The left seems fine. I do think it is not as good as when it was first done and it could be a sign of impending doom! Other than the minor binding, my Egg runs well so far. 


_Modified by irbrenda at 7:43 PM 12-30-2004_


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## archrenov8 (Nov 22, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (irbrenda)*

There are definitely two motors when you have the rear diff lock. Here is a quote from previous post of mine (http://forums.vwvortex.com/zerothread?id=1673090&page=2):
"Actually, as it turns out, they had replaced the center differential stepper motor twice, to no avail. So this last time when I brought it back to VW with the Brakeshop Warning fault the same morning I had picked it up (after the second center stepper motor replacement), they were totally frustrated. VW Tech line told them to also replace the rear stepper motor. I had them keep it for the weekend, to make sure that it was really fixed, and it went the whole weekend without faults.
So, at least for me, maybe, it was the rear stepper motor all along, and not the center, or maybe it was both. I guess the fault codes/diagnosis do not distinguish between stepper motors for this warning."


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (archrenov8)*

I know, this was the exact post I was referring to above. I'm just trying to get some other confirmation that this is actually true since the above post was the first I'd heard of their being two.


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## mdjak (Aug 13, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

Noc, I feel for you. That beautiful white with teak Egg, binding and scrubbing. That plain sucks. And what's even worse is that you have to fight with them to get it fixed and go back again and again. That's what is actually souring me. I understand cars, all cars have problems of one sort or another. But when the service department just thinks you can keep coming and coming, like the Eveready Bunny, that you have nothing better to do, it is infuriating. And my dealer doesn't even care. They just continue to lie. That's the thing I can't take. I wouldn't even have bothered to show them pages from this forum. My dealer would use it for toilet paper, instead of posting it on the walls for the so-called mechanics to look at and learn from.
It seems as if there really is no such thing as a car mechanic at VW any more. They are like robots who follow drawings on very poor computer screens. Point: When my horn went out, instead of looking and doing a minimum amount of work to change it, such as Spock suggested and did himself, they removed both headlights and the front bumper. As a result, they didn't lock in one of the headlight assemblies and I did it and would up breaking the locking mechanism.
They just don't care.


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## chickdr (Nov 28, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

For ours BOTH the stepper motor and TCM had to be replaced to stop the binding. The stepper helped but until they did the TCM(on a second visit) the binding continued. Ours actually changed from when turning to the left to turning to when turning to the right after the stepper motor.


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## TREGinginCO (Jan 4, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (chickdr)*

Okay.... I talked with a VW tech yesterday and specifically asked about Stepper Motors vs. Differential Locks --- this is what I was told.

The TOUAREG ONLY has one (1) stepper motor regardless of the optional rear locking differential.
The TOUAREG has ONE or TWO differential locks depending on whether the vehicle is equipped with the locking rear differential or not.
If you only have the Center Locking Differential: You have ONE stepper motor and ONE locking differential
If you have the optional Rear Locking Differential: You have ONE stepper montor and TWO locking differentials (center and rear)
The stepper motor and differential locks are completely separate items.
The stepper motor involves the "gearing" of the drivetrain... the differential locks are for controlling traction on the 4WD system.

This is what I've been told - I hope this clears up any confusion.


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (TREGinginCO)*

Treging, this is great information and very helpful. Based on this, it begs the question: do the locking differentials have anything to do with the scrubbing/binding problem and/or the hill descent brakeshop fault warning?


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## TREGinginCO (Jan 4, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

Everything I've read/learned about the scrubbing problem - those have existed solely in the Stepper Motor/Transfer case of the vehicle.
As for the Hill decent workshop warning - I don't know, but this vehicle is complicated and it could all be connected in some way!!


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## sciencegeek (Oct 26, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

Regardless of the name affixed to the various motors, the binding/scrubbing problem, IMO, is due to the diff locks not being controlled properly by the differential lock motors. Gear reduction to low range, IMO, has nothing to do with binding/scrubbing.
You have one diff lock motor for each locking differential, center (on all eggs) and rear (on those with the locking rear diff option).
The term "Stepper motor" does not appear in the Bentley.
The term "Stepper motor", IMO, comes from the All Wheel drive self-study program, page 51, where the label "Stepper Motor" points to the differential lock motor. In fact, after looking carefully at both that document and at the Bentley, it seems that the same motor controls the locking force on the center differential as well as the engaging of the gears for the low range.


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## 4x4s (Dec 18, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (sciencegeek)*


_Quote, originally posted by *sciencegeek* »_Regardless of the name affixed to the various motors, the binding/scrubbing problem, IMO, is due to the diff locks not being controlled properly by the differential lock motors. Gear reduction to low range, IMO, has nothing to do with binding/scrubbing.
You have one diff lock motor for each locking differential, center (on all eggs) and rear (on those with the locking rear diff option).
The term "Stepper motor" does not appear in the Bentley.
The term "Stepper motor", IMO, comes from the All Wheel drive self-study program, page 51, where the label "Stepper Motor" points to the differential lock motor. In fact, after looking carefully at both that document and at the Bentley, it seems that the same motor controls the locking force on the center differential as well as the engaging of the gears for the low range.


Thanks for looking this up. That's what I thought I remembered too, but hadn't got around to doing the research (again) to verify my memory.


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (4x4s)*

This is great info everyone. So it seems to lead back to the original question: should I be insisting that the dealer replace both the center and rear diff lock motors (in addition to the TCM) in order to solve the scrubbing once and for all? Also, how do I get the dealer to agree to replace the TCM? So frustrating.


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## Black Touareg (May 27, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*

Hi there,
I have been reading the posts with interest. I sent our dealer an email outlining some of the technical information I had picked up from previous posts last week. We took our to the dealer this morning to have the shuddering/vibration problem sourced and fixed. They called and told me they want to keep the car overnight and drive some other Touaregs on the yard tomorrow to compare.
It sounds to me like VW Australia has not issued a TSB re this and the dealer is bumbling along. Hopefully we will get somewhere.
Again, really appreciate people sharing their knowledge, it has at least given me a place to start from. Other than that the Touareg is a terrific vehicle.

























_Modified by Black Touareg at 4:11 PM 1-11-2005_


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## jinxegg (Oct 14, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_This is great info everyone. So it seems to lead back to the original question: should I be insisting that the dealer replace both the center and rear diff lock motors (in addition to the TCM) in order to solve the scrubbing once and for all? Also, how do I get the dealer to agree to replace the TCM? So frustrating.

Don't get frustrated and try to avoid emotional reactions,as they tend to be very costly most of the times.
Tire scrubbing is caused by a locked diff irrespective of high/low gearing.
If your front tires are scrubbing, it means your central diff is locked and cannot compensate for the difference in speed between your front and rear wheels, when you make a sharp turn. 
You can even feel a play at your steering wheel coming from the front wheels jittering as they are forced to turn in the wrong speed for their angle and the radius they follow.
If your rear tires are scrubbing, it means your rear diff is locked and cannot compensate for the difference in speed between your inner and outer rear wheel, when you make a turn.
In this case the wheel jittering can be felt through the car's body and not the steering wheel.
It's ok to lock your diffs in low traction conditions(ice,snow,mud,sand)as the tires cannot bind on a slippery surface, therefore differences in wheel speeds are compensated by tire slip. 
However, even under such conditions, rear diff lock should be used for straight line driving only in speeds not exceeding 12 mph.
Operating on dry pavements with locked diffs you run the risk or seriously damaging driveline components.
Epilogue: Determine if front or rear tires are binding(most probably front ones) and you know which diff is locked.
If you have a good service dealer will be a no problem to address the issue and fix it.


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## Black Touareg (May 27, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (jinxegg)*

I just got the car back after 3 days. The dealer has replaced the stepper motor, upgraded the software in the transmission (no idea why) and apparently reflashed the computer. 
Anyway, the car at the moment is running/ turning smoothly. Just a question on the tyre wear. I know the tyre wear has been discussed at length, but is it related to the stepper motor problem? or am I way off.








thanks


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## Curjo (Nov 21, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (Black Touareg)*


_Quote, originally posted by *Black Touareg* »_
Anyway, the car at the moment is running/ turning smoothly. Just a question on the tyre wear. I know the tyre wear has been discussed at length, but is it related to the stepper motor problem? or am I way off.








thanks

Glad your problem was fixed -- Doesn't it make the car a joy to drive again? There is a relationship to the drive train binding and tire wear. VWoA has issued a TSB allowing the dealers to align the front wheels or reimburse the customer for front wheel alignment. I think a search will pull up the actual TSB number for you. Providing that information to your dealer may help in getting something similar down under.
Cheers!


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (Curjo)*

I hate to be pessimistic, but mine seemed fine after the flash (1st time) but then it came back after 2 weeks. Then after they replaced the stepper, it was fine for 2 days and then it came back worse. I'd be interested to see how you fare after about 2 weeks.


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## jinxegg (Oct 14, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_I hate to be pessimistic, but mine seemed fine after the flash (1st time) but then it came back after 2 weeks. Then after they replaced the stepper, it was fine for 2 days and then it came back worse. I'd be interested to see how you fare after about 2 weeks. 

Obviously they kept changing the wrong part....


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (jinxegg)*

the point is others on the forum have well documented that both the center stepper AND the TCM have to be replaced in order to fix the problem. the hill descent fault is fixed by replacing the rear stepper (if you have rear diff lock). Unfortunately, since "its not in the TSB" to replace the TCM, guess what? they won't replace it.


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## jinxegg (Oct 14, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_the point is others on the forum have well documented that both the center stepper AND the TCM have to be replaced in order to fix the problem. the hill descent fault is fixed by replacing the rear stepper (if you have rear diff lock). Unfortunately, since "its not in the TSB" to replace the TCM, guess what? they won't replace it.

Maybe your problem is not a TSB but a thorough inspection from your service dealer to the transfer case.
It is possible that prolonged use of the car with the central diff locked before your stepper motor was replaced has caused distortion to some mechanical parts inside your transfer case and changed tolerances between moving parts.
So a new stepper motor may perform ok but the mechanical operation inside the transfer case is zip.....


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (jinxegg)*

ive never actually used or driven it with either the center or rear diff locked.


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## jinxegg (Oct 14, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_ive never actually used or driven it with either the center or rear diff locked.

A faulty stepper motor locks the diff without you having selected the operation and without even knowing it till you experience the tire scrubbing, then you know it's there......


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (jinxegg)*

yes, understand. one question though, if the stepper is replaced though and the problem reappears in 2 days, what's the solution?


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## jinxegg (Oct 14, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_yes, understand. one question though, if the stepper is replaced though and the problem reappears in 2 days, what's the solution? 

If stepper motor and transfer case ECM ok, then check for distorted mechanical parts inside transfer case.......


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## meatster (Mar 9, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_yes, understand. one question though, if the stepper is replaced though and the problem reappears in 2 days, what's the solution? 

Unfortunately if you've escalated it up to the area service rep and they are denying the claim, they really aren't gonna do anything more until you twist their arm or embarrass them. That's how VWoA has always operated. If you really want to keep the car, pay for a TCM replacement and then sue them for not replacing it under warranty to fix the problem. 
Or call Arnold Diaz from CBS's Shame On You and tell him your story. After the whole towing fiasco I'm sure they would be licking their chops to run another story on the t-reg. Especially after a VW exec promised everyone a letter explaining the towing issue and true towing capabilities of the t-reg on Shame on You and never sent it. 
Better yet, get a bunch of people together that are having the same problem and threaten VWoA with a class action law suit. That's the only way VW was forced to fix the faulty window regulators issue a couple of years ago








Meat


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (meatster)*

or, just do as I've done and send them a lemon law buy back claim if they don't fix it. which, by the way, was received by them on the 10th and have not even contacted me yet. they have 10 days from receipt of the letter to fix it or they get a summary judgement against them for the refund. isn't that incredible?


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## meatster (Mar 9, 2003)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (noc)*


_Quote, originally posted by *noc* »_isn't that incredible?

I'm not surprised. People keep forgetting this is VWoA. Except for isolated instances, they've NEVER been known for their customer service. When was the last time you saw VWoA in the top ten any of the JD Power rankings?? We all got a great truck at a cheap price from a company that isn't doing well financially of late. There is not much room in there for customer service beyond the bare minimum...
Meat


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## noc (Feb 15, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (meatster)*

I suppose. Doesn't sound like a winning formula though does it? (rhetorical, no need to answer







)


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## Black Touareg (May 27, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (Curjo)*

G'day,
The car is a pleasure to drive again (fingers crossed) and so far no binding. Lets see how we go.
I will follow up that TSB on tyres though. We replaced the first set after 14k because the fronts were badly worn on the outside edge.
Thanks


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## Dodgie (Apr 1, 2004)

*Re: TREG w/Rear Diff: one stepper motor or two? Need definitive answer please (Black Touareg)*

G'day Sydney (Black Touareg) - presume that was the Dunflops that went at 14000km? What did you put on? I had one (left front) start to scrub out but they were all worn out by 20000 km anway


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