# Brake Assist Workshop Fault... with a twist



## noc (Feb 15, 2004)

Well, so much for my over a year and a half of trouble-free driving with my "new" replacement TREG. At 19,000 miles i've just gotten the dreaded "Brake Assist Workshop" fault. I know this = stepper motor problem, likely on the center diff. But here's the rub (or lack thereof)... I don't have any scrubbing or binding. So what do you think is wrong with it?


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## henna gaijin (Jun 30, 2005)

*Re: Brake Assist Workshop Fault... with a twist (noc)*


_Quote, originally posted by *noc* »_ So what do you think is wrong with it?

Sounds like it could be a spurious low voltage fault.
I'd throw a charger on it for 24 hours and see if it recurs.
HTH


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (henna gaijin)*

could be. here's my little test though: when the fault is not lit (i.e. after restarting) I put the TREG in N and shift to low, then center lock, then rear lock. The orange dot representing the center locking diff is present, same for rear lock. When the fault light IS lit, I do the same test only to find the center lock diff is NOT filled in orange but the rear is. This is what's leading me to believe there's a problem with the center lock. But, as we all know, things are not always what they appear to be when it comes to the TREG.


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## aircooled (Jul 30, 2003)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

Bad switch? Bad plug? I'd put a VAG-COM on it to see exactly what the fault code is before guessing.


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## Sweeper (Jun 5, 2006)

*Re: Brake Assist Workshop Fault... with a twist (aircooled)*

VW flash for the stepper motor may help, it has been out for about one week, you may want the dealer to that fist before you start diag your self.


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## archrenov8 (Nov 22, 2003)

*Re: Brake Assist Workshop Fault... with a twist (Sweeper)*

What models does that flash apply to? And any idea as to what it perports to fix? I have had many repair attempts and a new stepper motor, and still have the scrubbing on normal, low speed turns.


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## TREGinginCO (Jan 4, 2004)

*Re: Brake Assist Workshop Fault... with a twist (archrenov8)*

I've never heard of a "flash" for the stepper motor. If it's bad... it will be replaced.
I'm with Aircooled --- could be a bad switch.


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## Yeti35 (May 17, 2006)

I had this come up once about a week ago but it went away to never return after I shut the car off. I called the dealer on it for I was about to leave on a trip a few days after and they said not to worry about it till it came on and stayed on. I had no scrubbing issues or anything either. It in fact came on after an emergency stop in traffic, which I felt was odd. Still has not come back since it went off. I am keepin my fingers crossed it was a fluke.


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## joshieca (May 23, 2005)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

I had the same thing happen, only when my BAW lit up so did the ABS fault system, and the on board computer said that the downhill assist wasn't working and the center console where you can change from high to low diff was flashing. After turning off the treg it went away, only to return a few days later. This went away after I turned the treg off again....so I took it to the dealer. My dealer had it for 5 days, replaced some sort of computer...I hope it doesn't return.


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (joshieca)*

I had the flashing around the diff lock knob as well


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## joshieca (May 23, 2005)

*Re: Brake Assist Workshop Fault... with a twist (noc)*


_Quote, originally posted by *noc* »_I had the flashing around the diff lock knob as well









Yep...like I said when mine went off the ABS system failed also. I heard no noises, no grinding, etc., the handling did not change and the brakes still worked. My dealer said that the traction control system was off as was the ABS system when those warnings came on, but only if the warnings appeared on the screen. They replaced some sort of computer control unit







; I hope that it doesn't reappear.


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## fauvaydoc (Apr 2, 2003)

*Re: Brake Assist Workshop Fault... with a twist (TREGinginCO)*


_Quote, originally posted by *TREGinginCO* »_I've never heard of a "flash" for the stepper motor. If it's bad... it will be replaced.
I'm with Aircooled --- could be a bad switch.

Just to let you guys know, there is a new flash for the center diff stepper motor control module (like Sweeper says). It is supposed to eliminate the scrubbing/binding issues without replacing the motor by altering the locking strategy in corners . It may be unrelated to noc's problem though.

_Modified by fauvaydoc at 11:05 PM 7-8-2006_


_Modified by fauvaydoc at 11:06 PM 7-8-2006_


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## awadw (Jul 11, 2006)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

I have an 06 V6 Treg and I had that light come on once. It went away after restarting. I don't have the scrubbing noise but the car feels it is going to die after coming to a full stop. The RPM goes down 3-4 times tp around 3 and bounces up. It seems that it is doing the shifting down in the last minute. It does not do it when I put it in neutral. 
Do you think it is a step motor problem? The dealer says there is nothing wrong eventhough they see what happens when I come to a full stop.


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## henna gaijin (Jun 30, 2005)

*Re: Brake Assist Workshop Fault... with a twist (henna gaijin)*


_Quote, originally posted by *henna gaijin* »_
Sounds like it could be a spurious low voltage fault.
I'd throw a charger on it for 24 hours and see if it recurs.
HTH


So, did you charge it up?
What happened?


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## cybulman (Dec 18, 2003)

*Re: Brake Assist Workshop Fault... with a twist (fauvaydoc)*

Is that TSB "OD"?
I recently took mine in for a (non-compulsory) change of oil at 15,000 and check up as I was driving 2000 mile roundtrip and they did a TSB named OD.
Cy


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## awadw (Jul 11, 2006)

*Re: Brake Assist Workshop Fault... with a twist (cybulman)*

I checked it out way back and The OD TSB is for 04 and 05 and My VIN is not included in that for my 06. I alraady did the TCM (Transmision Concrtol Module) flash.
When in Idle it is fine no problem and When I put it in Neutral as I am coming to a stop. only when I come to a stop not in neutral and the car is shifting down. I also sometime here a Knock in the tranny when stepping on the gas and I am in 2nd or 3rd Gear and going at 20-25 MPH. Not sure if they are related.
It is weird.


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (awadw)*

I don't have a charger so didn't charge the battery. But, even stranger now, after gettting the fault like 4 times in a row, i haven't gotten it since. Oy vey.


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## mary m (Jul 23, 2006)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

I've also had this issue where brake assist/abs/rear differential warnings were coming on almost anytime I drove for more than 30 miles at a time. Had it to the dealership and they acted as if they had never encountered such a thing and finally ran the diagnostic machine on it (sorry I'm not technical). Said it was software glitch in rear differential ecm, ordered part and replaced it. The day after the thing was replaced, the problem started again. Will be at the dealership again this week to have them look at it again. Dealership told me there was not a negative implication if the error lights come on --- that no system has failed and everything still works so I should not be concerned with driving it while the problem is active. 
Would people here agree?


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (mary m)*

going in for 20K service on Friday. So we'll see what fault codes, if any, pop up...


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

OK... here's the update. took it in last friday for 20K service. i told them of the fault warnings i'd been getting, although they've completely disappeared over the last few weeks. I also told them that my keyless entry was starting to weaken, meaning key in pocket, touch handle, doesn't open, etc. so $400 (!) later, the 20K service is done and they tell me, "no fault codes found at all, for anything." so therefore, no answers for the brake assist or the weak keyless entry. i leave in somewhat disbelief. 
Sunday, I'm with my daughter at a softball tournament all day. We go to leave and guess what? battery is dead as a door knob. nothing works. i get a jump, it starts. i go home. all fault codes go away, it starts up again normally as if nothing happened. I bring it back to dealer on monday morning. explain everything. they bring it in, check everything out. tell me i have a dead battery - won't hold a charge. nothing else found wrong. replaced battery, went home. i guess we'll see what happens next, if anything. 
here's the topper... SM said maybe when they load tested the battery during 20K service, it pushed it over the edge and killed it!


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## henna gaijin (Jun 30, 2005)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

noc,
Buy one of these:
http://www.autosportcatalog.co...=3480
It is a battery charger/maintainer made by CTEK.
Use it frequesntly and say goodbye to battery issues.


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## spockcat (Jun 5, 2003)

*Re: Brake Assist Workshop Fault... with a twist (henna gaijin)*

There really is no reason why he should need a battery charger if he uses the car on a weekly basis. Maybe the battery went bad, or maybe he has an electrical problem. Either way, a battery charger won't fix the problem.


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## henna gaijin (Jun 30, 2005)

*Re: Brake Assist Workshop Fault... with a twist (spockcat)*


_Quote, originally posted by *spockcat* »_There really is no reason why he should need a battery charger if he uses the car on a weekly basis. Maybe the battery went bad, or maybe he has an electrical problem. Either way, a battery charger won't fix the problem.

Could be, but it has been my contention (and experience) for awhile now that the charging system (alternator/cables/battery) in the V8 is marginal.
Maybe this is because the system was originally designed to have two batteries - I don't know.
What I do know, however, is that without periodic charges the battery in my V8 falls below the minimum recommended 12.5V.
Combine a lack of periodic charging with several short trips only and I start to see what I call spurious low voltage faults.
The first of these faults, interestingly enough, is that the red light around the keyless start button does not light upon entry.
Further faults are the various "workshop" faults with driveline schematic warning lights, flashing console knobs, etc.
All this goes away (and stays away) with periodic use of a battery charger.
Am I simply fixing a symptom and not addressing the root cause of this problem? Maybe, but my battery tests fully up to spec. The truck performs perfectly for weeks at a stretch without supplemental charging. My voltmeter is pegged at 14V even when under heavy load.
My suspicion is that many of the problems we see on this board are due to chronic undercharging of the single battery in the V8's.
Call me crazy







but periodic supplemental battery charging is an elixer for my V8. After a complete recharge I even think the transmission shifts smoother. My imagination? Could be, but the Touareg has a lot of electronic "stuff" going on which I am sure works best with a fully charged battery in the loop.


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## DenverBill (Apr 18, 2003)

*Re: Brake Assist Workshop Fault... with a twist (henna gaijin)*

I also occasionally use my Porsche battery maintainer if the Treg is going to sit for more than a few days, particularly when the temperatures are at extremes. So the ranks of asylum grow


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (DenverBill)*

well, i certainly hear the logic, but i think i'm with spock on this one. why the heck should you have to charge a battery on a $50K vehicle? it should "just work." also, my voltmeter NEVER dropped below 14V ever, not once. i'm still suspicious that something is awry in the electrical system. i think i'll keep those jumper cables handy


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## Sweeper (Jun 5, 2006)

*Re: Brake Assist Workshop Fault... with a twist (archrenov8)*

The Flash is the replacment for the TSB regarding any steper motor or transfer case replacmnets, it applies to all Touareg years and Vins to Date. And I have it and seems to work very well, Ask your dealer about it they should have it.


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (Sweeper)*

another update... well, it appears that "something" likely caused the battery to die after all. today, on my way to work, just as I was passing my VW dealer on comes the fault warning again! so i turned right in, left it running and they took it in while the fault was lit. they called the VW Tech Line and were advised to do the flash - probably the one talked about in this thread. Tech Line said see if this solves the problem. if the fault reoccurs, then bring it back and they'll try something else. oy vey.


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## henna gaijin (Jun 30, 2005)

*Re: Brake Assist Workshop Fault... with a twist (noc)*


_Quote, originally posted by *noc* »_another update... well, it appears that "something" likely caused the battery to die after all.

Whatever you do, do NOT charge the battery


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (henna gaijin)*

latest... flash did nothing. here's how i got the fault to come back: put TREG in neutral, rotate the diff lock knob first to low, then center lock, then rear lock. FAULT immediately comes on. Little orange dot that shows the diff lock engaged (center) disappears. but rear lock dot stays on. so, appears to be an issue with the center locking diff. any ideas on what it could be?


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## henna gaijin (Jun 30, 2005)

*Re: Brake Assist Workshop Fault... with a twist (noc)*


_Quote, originally posted by *noc* »_ ... any ideas on what it could be?

With your ignition OFF, measure your battery voltage at the battery posts under the hood.
This voltage should be a minimum 12.5V.
If it is not, as you engage electrical consumers (e.g. diff locks) battery voltage will eventually reach a point where low voltage faults will start to be thrown.
One thing you could try is inducing the fault the same way you described, but with a second battery hooked up with jumper cables. See if it still throws a fault.
Couldn't hurt to try, right?


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## aircooled (Jul 30, 2003)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

Bad differential controller. This is exactly what I had, but I never received a message in the MFI. Also, my vehicle wouldn't easily shift into High range from Low.


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## Slimjimmn (Apr 8, 2006)

*Re: Brake Assist Workshop Fault... with a twist (aircooled)*

bad stepper motor.
doing a reflash on a vehicle that already hasa bad stepper motor wont do anything. If the motor is bad, its bad, no reflash can fix an internally faulty motor. (brushes worn)


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (Slimjimmn)*

here's the latest. TREG back in today to address the faults I described earlier (center diff lock engagement setting off the fault). They decided it was a bad stepper motor and replaced it. No flash or replacement to the control module. I guess I'll find out when I pick it up in a little while. I'm just hoping they didn't put an older stepper motor in that causes scrubbing/binding where I had none previously!


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

one day later... the fault warnings from the center diff are gone. no binding or scrubbing as of yet. don't know if this had anything to do with the dead battery issue? anyway, here is the part # of the stepper motor they put in: 1 OAD-341-601-C
That seem like the right one?


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## Sweeper (Jun 5, 2006)

*Re: Brake Assist Workshop Fault... with a twist (noc)*

You have to have a load intervention concern with car that is causing the fault when that system is shut down, parasitic draw test is needed and a alternator running test is needed.


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## noc (Feb 15, 2004)

*Re: Brake Assist Workshop Fault... with a twist (Sweeper)*

can you explain that in plain english for me?


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## highlander99 (Sep 2, 2006)

I live in Rio de Janeiro, Brazil and my my 2004 V8 Trg with 25 thousand Kilometers has been wonderful. I travel from home to work and back everyday without problems. the distance is approximately 20 miles round trip. The message Brake assist Workshop warning light has been coming on an off together with the ESD and ABS. After shutting the car off and turnig it back on immediately the warning lights dissapear. Two days ago, I was driving home at night with my lights on, stereo on and was playing with the on board computer settings. The next morning the car was dead as a door nail! So, I was worried about doing a jump start and called my dealer. They indicated that I probably had a bad battery and should change it. My next step was to go to the local battery dealer and have someone go to my home and change the battery. To my surprise, the battery is located under the driver's seat. I called the VW dealer again and was told to do a jump start and take the truck in to have the seat removed by the dealer in orderto change the battery! This reminded my of my Porsche 928 which needs to have the engine removed to change the spark plugs! Anyway, the battery guys put a special tool in my car and I started the car without problems. I have been driving the Trg since and it starts up perfectly, the V meter is pegged at 14 volts but the damm Brake Assist Workshop Fault light is still coming on and off. The Trg is somewhat special in my country and there are not too many around (it costs $140 K for a new V8!!) so the VW SM are not too experienced with this vehicle, therefore, I would like to get some ideas from you fellows so, when I go in to the VW dealer on Monday, I am prepared to argue and give them ideas on what could be wrong. Funny thing is that the Trg had a brake pad change at the same dealer and a computer check which showed no faults!!!
Thaks in advance for the help!


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## totokindom (Apr 4, 2006)

*Re: (highlander99)*

Mine died too would not start key stuck in ignition and battery was good. It turned out to be the Start Arthorziation Module you might want ot start there.


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