ABS warning Light

2000 Jetta tdi std. Warning light came on when my wife was driving yesterday. Fluid level was down a bit in canister so I added a bit even though it was well within the marks. Drove about a mile and tried the brake on ice. Heard them work. Shut car off for 30 seconds and restarted. Light went out. All ok until I made about 100 miles today and it came back on! Tried on ice and no ABS sound. Saw my neighbour in the yard. He has a 2001 tdi auto and guess what. His light came on yesterday too about the same time. The weather was near freezing with rain and snow all day. Could this cause it?? His did not go out and is still on. Any help would be appreciated.

Rain and snow. You answered it. They get crap on the sensor and ring and qite working. A VERY common issue. Nothing you can do about it.

Light still on today and not working. If I park inside a warm garage overnight will it correct itself? Neighbour is taking his to a garage (non dealer) today so I'll see how he makes out.

You should get someone with a vag-com to read the fault codes in the ABS comptuer. That will tell you what it thinks is wrong...

-J

I am many many miles away from Vag Com. Will an ordinary OBD2 read the ABS? Waiting for my neighbour to come home this evening to see how he made out at the local garage.

Dump question, but how is the wear of the front pads. You have a sensor that will pop an ABS warning light if the sensor in the front pads wear.

Wrong sensor, edited out

Dump question, but how is the wear of the front pads. You have a sensor that will pop an ABS warning light if the sensor in the front pads wear.

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MD, is the worn brake pad light and the ABS warning light one in the same? I think they are two different lamps.

They are totally seperate. The worn pad light is just a dumb circut, when it opens the light comes on.

I'm pritty shure you'd need a VW spicfic scan tool to look at the ABS controller. Maby pick up a vag-com? Even one of the cheap ebay units and the freeware version would be helpful...

-Jason

What probably happened if it has not gone out is it got loose and rubbed on the rotor causing the wire casing to wear through. That grounds out the sensor and it won't work. they are a real PITA it change too. VERY TIGHT. expensive little bugger as well.

original quote by: dieseldorf

MD, is the worn brake pad light and the ABS warning light one in the same? I think they are two different lamps.

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Below post.

The brakes look good redone about 20k ago and all highway driving. The other brake light was on when the sensor wire wore through, not the ABS.

Mileage dude. They DO NOT go on at that point. you are confusing lights. Only come on if there is another problem. Totaly different sensor.

Ya, the ABS light says ABS in the US and in canada has a circle with ABS in it. The brake wear light is a circle with these 1/4 circles around it. That light is in the very middle of the cluster, the ABS light is in the speedo, at least on my car.

-J

original quote by: jasonTDI
Mileage dude. They DO NOT go on at that point. you are confusing lights. Only come on if there is another problem. Totaly different sensor.

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You're correct. I am wrong. The ABS light did come on and not the brake warning icon. The front brakes needed replacing but it was not the problem which triggered the ABS light, matter of fact, I do not believe the brake wear icon ever triggered.

I should delete or edit out those other posts above. I do remember that when the rotors were removed, especially the rear rotors the gear cog on the axles seemed mighty rusted. Before we placed the rotors on it was a real clean-up dust job getting these gear cogs on all four corners of the car. In this situation there may have been an ABS sensor due to the poor state of the rusted surfaces on the ABS gear cog.

Sorry for the confusion.

M.D.

MD,

Yeah the metalic brake dust gets on the gears for the ABS as they are slightly magnatized. If the stuff is dry and you are outside compressed air will blast it off effectivly or inside brake cleaner will do it. This can trigger the light often as well. Just too much crud on the sensor.

Well I haven't been able to get it inside yet but I stuck my air hose in behind the wheels and blew off the brake ass'y. I can see/feel the wire hookup to the right front wear sensor light and the electric hookup at the back brakes. Is this the ABS sensors? Anyway the light went out after that but came back on again for about 20 minutes on the highway yesterday so maybe if I get it inside and take the wheels off I can see what I'm doing and clean it up properly. Thanks.

Yesterday both the girlfriend and I had ABS warnings. Mine sounds almost exactly like Northman's. We've had high winds for the last 5 days and recently rain, snow and now freezing temps. I came to the forum today just to confirm it's weather related. Our accounts are as follows:

The TDI sleeps in the driveway. Immediately after moving it, the ABS light came on solid and the red brake light began blinking. After about 10 minutes I had a chance to shut the motor off and restart. problem ceased and has not returned.

Girlfriend's Passat started acting up while driving home last night. Problem would come and go -- mostly after right turns. She got the ABS light, long beeps and her MFA warned her to stop driving the car. In lieu of my similar experience I told her to ignore it and ensured her the car would be fine after a night in the garage. Today all is well.

Just finished replacing my ABS sensor, and after I got it out, realized that it probably could have been cleaned in place. The sensor contains 2 magnetic bars about 1/8th of an inch apart, ebedded in plastic and suspended about 1/32 of an inch above a ring of cast indentations on the back of each front wheel rotor hub. Bits of iron and rust that flaked off the rotor had shorted the two magnets. If you take the wheel off, you should be able to snake a piece of cloth between the sensor and the rotor to clean it.

I haven't tried this but it should work to clean the sensor in place:
- use a VAG-COM to find out which side is complaining, otherwise you'll need to clean both sides.
- turn the steering so that the rear of the wheel, on that side of the car with the bad sensor, sticks out from the car.
- jack up and remove the wheel from that side, and look over the top of the rotor at the inside of the rotor hub, to find the ring of indentations. An electrical connector links the sensor to a wire comming down from the top.
- Try cutting a 1/2 in strip of shop rag, and then attach a "snake" by doubling up a thin strip of duct tape and attaching to both sides of the shop rag. Use the duct tape to "snake" the rag strip between the sensor and the rotor.

If that doesn't work, a replacement sensor is about $70, and you'll need to know which side is bad when ordering. Removal is tricky, and folks often destroy the old sensor taking it out. Mine did come out undamaged using the following procedure:
- remove the brass allan cap screw that secures the plastic arm coming off the sensor.
- wedge a screwdriver between the rotor and the gap under this plastic arm and apply steady pressure (but don't break the plastic arm off). Nothing will budge at this stage.
- while applying pressure with a screwdriver, use a socket extension to tap and rotate the plastic arm you just removed the screw from. The entire sensor will rotate gradually, and as it does, it will start to come out, because of the pressure from the screwdriver.
- once the arm is rotated until it hits the wheel casting, wedge something between it and the casting to rotate it back, then repeat the steps above.
- If you need to disconnect the wire from the sensor, the plastic clip on the inside of the sensor needs to be released first. Its delicate, so be carefull not to break it off.

Thanks for all this info. My earlier atemts at blowing it clean with air didn't seem to work as the light still is coming on, So will try to get it in the garage and do a better cleaning. Thanks again.

Well finally got it inside and pulled the front wheels. Tried the shop rag trick to cleaned the sensor and ring and blew out well. Didn't use any brake cleaner or anything. But I still have the light. It goes out occasionally but seem to be on more and more. What about the back wheels? I see the parts list one speed sensor there and one rotor? Maybe I'll pull the back wheels tommorrow. By the way, the instructions you posted worked well for the front.

Well I never got around to the back wheels but my cleaning of the front using pogos instructions may have finally paid off as the light has been out for a couple of days now. The neighbours 2001 went to a shop(non dealer) and the bill was $125 but the light was back on the same day. He is taking it to a dealer this week. Hopefully I'm OK now. Thanks again.

It sure is a small world. I have a 2002 NB with 64K miles and the ABS has been acting up just like Northman's since about 45K miles. Pulsing under light braking, happens at random. ABS light came on and went out the next day just recently; dealer replaced the left front sensor, didn't fix the problem. Dealer and VW of America don't have a clue on how to find, or fix this safety problem since it was first observed; what is worse is that it appears that they really do not care! How can such a critical safety function (brakes) on a car be ignored by VW?

I just started having this problem a few days back (among a few other problems). I feel intermittent vibration from my accelerator, brake, and clutch (most the brake), as well as steering wheel when I'm slowing down. ABS finally come on yesterday and I had my Vag-Com handy. Scan picked up front right wheel speed sensor. I really don't remember seeing the sensor on the right side. The driver's side was as clear as day when I did my coilover installation. I'll have to study my Bentley manual and try some brake cleaner.

I can't fault this on snow, we just don't get snow in my area of California.

ABS Speed Sensor removal (frustrated version)

If the above method does not work… it’s time for more force and power.

The wheel is off from before

Remove the brakes. There are a couple of allen screws on the back side that need to be removed after which the caliper should come off. Once off, find something to prop it up on to keep from damaging the wire that attaches to the pads (wear sensor, if I remember right). I used the tire for this as it was handy.

Remove the rotor. To do the above you will need to have access to a impact screwdriver for the screws holding the rotor on. Don’t try this by hand, it doesn’t work. You’ll only bung up the screw. A friend of mine suggests drilling them out and being done with them as they are only needed during assembly to keep the rotor on going down the line. I had an impact screwdriver, it was handy.

Unplug the old ABS speed sensor, and keep the cord out of the way.
Now you have access to both sides, kinda. The ring with the spaces that the magnet counts will remain on, sorry… Not an easy piece to remove.
Using a chisel and a hammer cut off both sides of the old ABS sensor. It’s plastic, you should have no problems cutting it off. This was one of the major problems I had with the other methods. The plastic was melted such that it was over both sides of the metal. The piece was not going to be pushed through using the above method.

Once the sides are cut off, push the guts of the sensor out. You will find it consists off a coil of copper wire and some stuff. I pounded on it from both sides till it was quite destroyed before pushing most of it through from the back and out the front.

This left me with a ring of plastic that I found to be mostly melted into the metal. Great.

My large chisel fit tightly, and I pounded it in tight. I was then able to use some channel locks to lock onto the chisel and begin twisting the chisel. Once the ring of plastic was broken free from the metal I was able to pull the ring out from the back. Finally! The old sensor was removed. In many small pieces.

I coated the new sensor with never seize. I don’t know if that will help. I hope so, but promise nothing. The liquid in the never seize should evaporate leaving a dust of metal oxides which should allow the piece to be slipped out more easily (provided it doesn't melt over the sides again)

Assembly is reverse of disassembly (without all the destruction). I put the screw in the rotor back in cause I'm like that. It's up to you.

Assembly is reverse of disassembly (without all the destruction). I put the screw in the rotor back in cause I'm like that. It's up to you.

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You may need to remove the corrosion of the hole with a dremmel to be able to push the new sensor in.

Well here is an update. After several clean up tries that sometimes kept the light off for several weeks and talking to several local owners that told me they had paid a lot of money to dealerships to do repairs that did not solve the problem, I decided to ignore the light. It was on all summer this past year which was no problem as there is no ice in summer. The odd thing is that on the first day of freezing rain in October I looked down and the light is out and has stayed that way for three months. The ABS is working just fine and I am at a total loss as to what causes all this. For sure it is a design flaw.

Well, just to give an update I have to report that this summer the light started coming on again randomly. Getting close to 300 Km and hoping for 500k. When it does go out it seems I do have ABS. (Hard to tell in summer as even up here we don't have ice) BUT all the tell tale ABS noises, and pedal vibrations occur as if the wheels were encountering ice. When the light is on the brakes work normally. Has anyone else encountered this. Would a vacumn leak/ boooster problem possibly be the cause.?? Many of my TDI friends here have put tape over the light and given up. For me it has been a random problem, and I have had some luck with cleaning sensors etc. but I've also had the problem dissappear for months on end with no action taken. Friends who have taken theirs to a dealer have spent a lot of $ and really haven't had any results so this is frustrating to say the least.

Find out why the light is on. A quick scan of the ABS computer will tell you why it's grumpy.

-Jason

Bump.

i never saw this thread but being a half decent mechanic here is what i did to my car:

once i removed the rotor and abs connector, i took a #3 flat tip screwdriver and chiseled off the front of the sensor then the back. that left the ring and copper wire filling. use the same screw driver to push out all the wires and then take the screwdriver and cut a slot all the way through the plastic ring and it will buckle and push right out. take a dremel or air tool and cut enough out to slide your new sensor in. coat the tip in vasoline and put it back together.

took me about 20 min per side. better than the 2hrs i heard it would take.