94, MB. Dash light ASR.

Tyre wear is related to the load you put on your tyres and the pressures you run them at, many tyre suppliers have charts to show you visually why your tyres are wearing and what you should do. Low pressure and high pressure both stress the tyres more than the correct pressure. There is a guide to what pressure your tyres should run at for light and heavy loading, adjusting the pressure for a trip can also save fuel and improve handling. VW recommend 28 Psi all round for your 2003 Passat on standard Tyres.
The ASR light indicates that your stability control system is working, if it is just cutting in as you hit adverse conditions then it is working how it should, if it is staying on go talk to your VW Mechanic , there may be a fault, try turning the ASR button on and off on the dash.

Not without clearing codes. And if the check engine light is on due to an actual problem, it can turn the other warning light on too so you know those systems are disabled. Usually a problem with ABS or traction control will not turn on the check engine light.
Your owners manual would talk more about what the lights mean.
I would have the engine computer scanned for trouble codes first.

Anti lock brake system light comes up when there is issue with car brake systems.It can be low brake fluid or faulty ABS fuse or its issue with brake system or assembly.Your vehicles brake system needs inspection.

To troubleshoot these issue,i suggest you to refer the help links provided below.There are direct links with accurate solution,for these specif issue.

Click the link below and follow the procedure:------

All types of ABS LIGHT / brake problems and repairs

http://howtobyme.blogspot.com/2011/11/abs-and-service-light-comes-on.html

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ABS light stays on but brakes work fine?

http://howtobyme.blogspot.com/2011/11/abs-light-stays-on-but-brakes-work-fine.html

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VCS and ABS lights go on and off intermittently on Lexus? http://howtobyme.blogspot.com/2011/11/vcs-and-abs-lights-go-on-and-off.html
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The ABS and Traction Control Lights stays ON dash of car? http://schematicsdiagram.blogspot.com/2011/06/abs-and-traction-control-lights-stays.html

------------- ABS & Brake lights warning indicator steady on dash and speedometer not working for Dodge Ram?

http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html

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Battery Light and ABS Light on Dash http://whoisbyme.blogspot.in/2012/07/battery-light-and-abs-light-on-dash.html

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Sometimes ABS light comes on while Driving? http://howtobyme.blogspot.com/2011/12/sometimes-abs-light-comes-on-while.html
----------- How Anti-Lock Brakes Work?

http://technoanswers.blogspot.com/2011/11/how-anti-lock-brakes-work.html

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Brake System Troubleshooting? http://technoanswers.blogspot.com/2011/11/brake-system-troubleshooting.html

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Anti-lock brake light stays on all the time?

http://technoanswers.blogspot.com/2012/01/anti-lock-brake-light-stays-on-all-time.html

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ABS light comes on and Car makes Grinding noise?

http://repairhelpcenter.blogspot.com/2012/01/abs-light-comes-on-and-car-makes.html

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ABS trouble codes for all models?

http://repairhelpcenter.blogspot.com/2011/11/abs-trouble-codes-for-all-1994-00-acura.html
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2008 Toyota Highlander: ABS warning light Blinking and OBD Error codes Coming?

http://technoanswers.blogspot.in/2012/05/2008-toyota-highlander-abs-warning.html

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2003 Lexus ES: VSC, TRAC OFF, ABS lights ON?

http://technoanswers.blogspot.in/2012/04/2003-lexus-es-vsc-trac-off-abs-lights.html

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2008 Toyota Highlander Hybrid: Warning Lights Abs, Vsc & Brake Are On?

http://technoanswers.blogspot.in/2012/04/2008-toyota-highlander-hybrid-warning.html

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ABS & Brake warning lights remains steady on dash? http://schematicsdiagram.blogspot.com/2011/12/abs-brake-warning-lights-remains-steady.html



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Can I drive the car without ABS fuse connected? http://schematicsdiagram.blogspot.in/2012/02/can-i-drive-car-without-abs-fuse.html

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Where is ABS/TCS module located on 2005 Cadillac Deville

http://schematicsdiagram.blogspot.com/2011/12/where-is-abstcs-module-located-on-2005.html

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ABS motor keeps running? http://schematicsdiagram.blogspot.com/2012/01/abs-motor-keeps-running.html

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When the car stops, abs pump turns ON? http://howtobyme.blogspot.com/2011/12/when-car-stopsabs-pump-turns-on.html

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Replacing ABS unit on Buick Century? http://technoanswers.blogspot.in/2012/02/replacing-abs-unit-on-buick-century.html

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2008 Toyota Tacoma: ABS causes Brake pedal fade? http://technoanswers.blogspot.in/2012/04/2008-toyota-tacoma-abs-causes-brake.html
-------------- Toyota Camry: Premature ABS Actuation? http://technoanswers.blogspot.in/2012/04/toyota-camry-premature-abs-actuation.html

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How to replace ABS Modulator Control Unit on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-replace-abs-modulator-control.html

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How to replace ABS Pump Assembly on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-replace-abs-pump-assembly-on.html

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How to remove ABS Accumulator on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-abs-accumulator-on-acura.html

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How to remove ABS Control Unit on Acura Integra?
http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-abs-control-unit-on-acura.html

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These details will help.
Thanks.

Anti-Lock Braking System (ABS)
Purpose Anti-lock brake systems (ABS) - generally also referred to as anti-lock
systems (ALS) - are designed to prevent the vehicle wheels from locking
as a result of the service brake being applied with too much force, especially
on slippery road surfaces.
The idea is to maintain cornering forces on braked wheels to ensure that
the vehicle or vehicle combination retains its driving stability and manoeuvrability
as far as physically possible. The available power transmission
or grip between tyres and carriageway should also be utilised as
far as possible to minimise the braking distance and maximise vehicle
deceleration.
Why ABS? Although today commercial vehicle brakes are designed to a very high
technical standard, braking on slippery roads often results in potentially
dangerous situations. During full or even partial braking on a slippery
road it may no longer be possible to fully transfer the braking force onto
the road due to the low coefficient of friction (friction coefficient (k)) between
the tyres and the carriageway. The braking force is excessive and
the wheels lock up. Locked wheels no longer provide any grip on the
road and are almost incapable of transferring any cornering forces
(steering and tracking forces). This often has dangerous consequences:
- The vehicle becomes unsteerable
- The vehicle breaks away in spite of countersteering, and starts to
swerve.
- The braking distance is significantly increased
- Tractor-trailer combinations or semitrailer trains may break away or
jackknife.
Load sensing valve influence On dry roads today's load sensing valves (ALB) alone are often capable
of preventing the wheels from locking if the vehicle is unladen; they also
help the driver to effectively grade the braking process on wet road surfaces,
but they are unable to prevent locking as such (no slip monitoring).
In addition, they are unable to counteract any overreactions on the
part of the driver, or any variances in frictional or adhesion coefficients
which may apply to different sides of the vehicle, or indeed to its different
axles (?-split road surfaces).
Benefits of ABS: Only the Anti-Lock Brake System (ABS)
- guarantees stable braking characteristics on all road surfaces.
- maintains steerability and generally reduces the braking distance
- prevents vehicle combinations from jackknifing
- reduces tyre wear.
Limits of ABS Although ABS is an effective safety device, it can not suspend the limits
defined by driving physics. Even a vehicle fitted with ABS will become
uncontrollable if driven too fast around a corner.
So ABS is not a licence for a maladjusted style of driving or failure to observe
the correct safety distance.
4
ABS Training Anti-Slip Regulation (ASR)
Anti-Slip Regulation (ASR)
Why ASR? Increasing the engine output (accelerating) on a slippery road surface
can easily lead to the maximum adhesion on one or all powered wheels
being exceeded causing them to spin, especially if the vehicle is unladen
or partially laden.
Spinning wheels when driving off or accelerating represent a safety risk
just like locked wheel do when braking.
Reasons - Wheels that spin transfer just as little cornering force as locked
wheels.
- They also no longer transfer any tractive power onto the road.
Consequences - Vehicles that do not move or get stuck.
- Vehicles that can no longer be steered, jackknife on uphill uphill
gradients, or swerve in corners.
Benefits of ASR ASR prevents the powered wheel from spinning and provides the following
benefits:
- Tractive power and cornering forces are maintained.
- Stable driving behaviour is ensured when moving off, accelerating
and negotiating corners on slippery roads.
- The indicator lamp (if installed) is used to warn the driver of slippery
road conditions.
- Tyre wear is reduced to a minimum, and the motor vehicle's drive
train protected
- The risk of accidents is further reduced.
ASR and ABS: ASR represents a worthwhile addition to an ABS-controlled braking system.
All that is required to turn ABS control into full ABS/ASR control is
an ECU with the additional ASR function and a few additional components
for controlling the differential brake and the engine. This why ASR
is only available in combination with ABS.
Even a differential lock for off-road use and ASR do not exclude but complement
each other.
Limits of ASR The traction capacity of an all-wheel driven commercial vehicle can not
be achieved by a motor vehicle with only one driving axle - not even with
optimal ASR.

Mostly this problem appends on winter time. I f you take your car to the dealership you could throw your money away like many people did and the problem still not solve. I fixed mine definitely by myself and you could do it too. 1- Open the hood, Jack the vehicle. On both front tires you will see a cable that looks like a Rca jack that connect to the brakes but it's bigger than RCA jack. 2- Follow that RCA cable to the hood and on the other end you will see 2 small white wires that bring power to ASR and ABS system cut those 2 wires and you automatically disable the ASR and you solve the problem. As you know the ASR system is good for snow, it's like a 4 by 4 and you will need it later to drive safely in bad weather when there is snow. What to do next. After cutting the 2 small wires, I put 2 swiches in case I need the ASR in bad weather.One swich for ASR and the other one for ABS. when you cut one wire you connect both ends to the swich and you do the same for the second wire that you cut. The only one thing you will see is the ASR and ABS light will turn on on the dash. When driving in bad weather, open the hood and turn on the swich to enjoy the feature of the ASR.. ASR=4 by 4

you will need to replace the ASR actuator assembly is this happens again, very expensive fix and all to common a problem

To make sure the problem will be solved, you have to replace left and right ETA's and engine wiring harnes.I had the same problem with my 1994 S600. expensive.Mercedes had wiring problems on all models from 1992- 1996 (insulation on wires would crack,and wires would short circut).

The ASR (acceleration slip regulation) light is for the ETA (electronic throttle actuator) it is a mysterious beast that controls throttle placement. I would say that you have one of two problems. Either the interior insulation of the wiring of the ETA is is crumbling or the wiring harness is disintegrating. Either fix isn't cheap although if I had to pick one I'd pick the wiring harness. It's about a third of an ETA. In short check he wiring to the ETA, look for damage or water intrusion, if nothing is found you will have to replace the ETA control.
READ THIS POST FROM A M-BENZ FORUM MEMBER ON ASR ISSUE
For two years I lived with the the ASR light coming on shortly after starting the car and had to either continue driving it in the limp home mode, or stop the car to restart it to regain normal engine operation with the ASR light out. Finally, it got so bad I simply took a chance, after discussing the problem with a reputable local indie, and bought a rebuilt ETA from Potomac German Auto and put it in. The part had a one year warranty with it and was about half the cost of a new unit from MB. There are other companies out there that rebuild these units as well. At any rate the ASR problem went away. To give you a reference point, my car had about 156,000 miles on it when I did this repair. That may or may not be significant to your situation, and I probably should have corrected this problem well before I did, but I didn't.

I also had the ASR light on and no power. It was the throttle actuator not working properly. I did a tune-up and the problem went away.

MB has ASR,  VW now has ESP.  You posted in Jetta TDI, but say you have a SL600.   Both are slip/traction control programs and both can be manually overridden by dashboard button.  When the ASR or ESP is locked out, the light will be on all the time, maybe you can just push the button?   When driving, if this light flashes on, then ASR/ESP is trying to help get the wheel that is spinning not to.  

If the light came on after replacing parts, or a repair job,  something may be wrong with the parts (non OEM), the service or a sensor may have been damaged.  

Check with dealer for a recall for your vehicle on brake switch ... vw had a recall on these around 2002-2005.