ABS warning light

[shamtec25]

Hi, I am new here and wanted to ask you guys for some advice.

I have had my S4 for about 4-5 months. I love it but am becoming frustrated with its "quirks"

I have got an ABS warning light and Airbag light continually on.

I have taken it to an Audi Garage and they plugged their diagnostics in and could not get any data from the car. They didn’t have time to look at it and would need it for 1 or 2 days?!! Don’t fancy paying 2 days labour at 70 quid an hour for them to tell me what the problem is.

I have since taken it to a Audi Specialist in Manchester who can also can not get a reading. He has chased the wiring and finds no faults. He thinks it may be the ABS control unit. But i can’t understand how that would cause the car's communications to pack up.

Does anyone have any ideas what may be wrong with my car? Or where I can get a cheap ABS control unit. I have been quoted over 1 grand for one from Audi. I have no Warranty [img]images/graemlins/frown.gif[/img]
Another quirk is that my car feels slow. But without getting any data from my cars communications i cannot get an idea what the problem is.

I have some more quirks but feel I have bored you enough already. My main worry is that this may be expensive and I dont have the luxury of a warranty.

HELP [img]images/graemlins/s4anogaro.gif[/img]

[Andiroo]

What you need first is one of our guys close to you who has Vag-com to see if they can get any data for you. Anyone close?

Failing that, IMHO I would go to either Revo or AmD and get the ECU checked for error codes. This could also explain the loss of power. You will probably find you will get everything fixed, along with an extra power remap, for a lot less than Audi would charge to fix just the ABS.

And something to check, if your brake pads are well worn this can affect the ABS sensor as well.

Good luck and keep us posted [img]images/graemlins/wink.gif[/img]

Andiroo

[SimonS4MTM]

Your Audi dealer should take the car and be able to investigat eit further, even if it takes up to 2 days, i dont think they will charge you because the are only doing daignostic work to find what needs to be repaired.

I have an abs light on a while ago and it turned out to be the ecu. I dont think you will find a cheap one, Audi charge about £230, you could get one from VAG parts cheaper, but its not a cheap fix

Good luck

[Dippy]

He thinks it may be the ABS control unit. But i can’t understand how that would cause the car's communications to pack up.

The S4's diagnostic system is based on a serial bus which connects all the control units. It is possible that a fault could occur which might knock-out the bus, because that's what seems to have happened.

Whilst it would be sensible to suggest that the ABS control unit has packed up, you also have an airbag light on so maybe it's that system. I'm afraid that since no-one can access any control unit to get the diagnostic information, further investigation is going to be more difficult.

The process should be to disconnect control units from the bus (starting with the ABS) until it starts to communicate again. In all likelihood, replacing the control unit which does this would probably solve the problem. I'd have thought that finding the fault should only take a couple or three hours.

On thing that seems to be true is that any inobvious fault like yours is going to cost a lot from an Audi dealer. I recommend that you go to a specialist as (a) they'll probably find the fault quicker and (b) will only charge you for the time they actually spend on it.

As mentioned, AmD are very reputable and would be worth the drive from Manchester.

[shamtec25]

Thanks for your reply’s lads.

My car is at the Audi Garage now who are doing a service and replacing the cam belt. The guy there seems reasonable and said they have had a look at it for a couple of hours for free and can’t find the fault.

He is keeping it for another couple of days to diagnose the prob and will give me a discount if it runs for into big money to diagnose.

Keeping my fingers crossed! (Why didn’t I take mechanics at school)

While it was there he asked when I had had it chipped and lowered. I had no idea it had been lowered or chipped and a fancy exhaust put on it. Wondered why I kept scrapping on the smallest speed bump.

So it should be faster than I expected not slower. The funny thing is when I bought it; it has a A4 1.8 badge on the back. I wonder who the last owner was trying to Kid.

I will give this garage a go but if they don’t come up trumps then it looks like a trip to one of the specialist that you have recommended.

Thanks

[Golich]

Shamsa,

I just finished reading this post on Audisport.net. Your problem appears to be quite well known.

Follow this US link. If like me you know bugger all about eletronics most of this won't mean a thing but it sounds like you ABS unit maybe the culprit and interestingly the VW unit is identical but cheaper. How much does that piss you off [img]images/graemlins/24430-audibash.gif[/img]

http://tech.bentleypublishers.com/threa ... 9&tstart=0

Dippy this link will make more sence to you [img]images/graemlins/thumb.gif[/img]

For the Audisport.net link see here

http://www.audi-sport.net/ubbthreads/showflat.php?Cat=1,10,15,105,200,900,1000&Board=a4forum&Number=38335&page=0&view=collapsed&sb=5&o=&fpart=1

Hhmm That looks a bit long in case it doesn't work look under the S4 b5 chassis under the post heading of 'ABS warning on 2.6 quattro'

I recommend AMD. [img]images/graemlins/thumbs.gif[/img] way better than any dealership [img]images/graemlins/nodder.gif[/img]

[Dippy]

That thread started off about possible wiring faults and how to find them using the Bentley manual instructions. But it ended with the conclusion that the original poster's ABS unit was dead. Then a few people implied that this was a common problem.

It's been years since I did any professional electronics work, but when I was a repair tech there were two schools of approach:
1) Use all your diagnostic skills to indentify the problem
2) Just replace all components one by one until it works again

No. 2 was often frowned upon by 'enthusiasts'. However in a 'un-plug/re-plug' system which I suspect exists on the S4, it is probably the fastest way. So really the garage needs to simply try a new ABS unit and see if it starts working. Of course that requires that they have a spare unit in stock.

[Dippy]

shamsa,

I just noticed that you think the car feels slow, and the garage told you it's been modded. There's no question in my mind now then that you should take it to a specialist. A company like AmD will charge about £120 for a full rolling-road run and that will confirm if it's OK or not. If not, only a company like AmD will be able to effectively diagnose the problem and fix it. There are enough stories about Audi dealers to suggest that it would be pot luck for them to solve the problem.

I don't want to worry you, but you should be aware of the potential problems. The typical problems which can result in low power are faults in the air-intake system. Of these the most common are air leaks (external or internal by DV failure) or MAF (mass air flow) sensor problems.

Now because of the way the ECU controls the engine, the turbos may work extra hard to try to give the performance that your right foot is demanding. Or for a MAF fault you might be running hot and that also stresses the turbos. In the long run these problems can result in turbo failure which is expensive to repair (in general the engine comes out and both turbos are replaced).

My car is always serviced by AmD, and I always pay for a RR run. That way I have peace of mind that the performance is right and that the engine is healthy.

[shamtec25]

Thanks again for the replys guys.

The more I hear about this AMD place the more it looks like I will taking a trip down there.

The article on the US website was very intresting and think I will ask the Audi garage to swop over the ABS control unit to test if that is causing the problem.

I will let you know how I get on, but may be a trip to AMD to solve the problem and have a Rolling road test done to see what BHP my car is running at.

[img]images/graemlins/tongue.gif[/img]

[Golich]

If your considering asking an Audi garage to swap out your ABS unit you'll find that won't be cheap. - get an estimate and hold them to it.

Personally I would have thought the one stop option of AMD for everything is both cheaper and less frustrating in the long run.

Plus I would look into how much cheaper a VW ABS unit is over an Audi one as it won't matter to AMD what they fit.

While you'll have to talk to the Audi dealership to get them to fit a VW one. Having said that it seems crazy to me as anyone that has bought Audi/VW/Seat/Skoda parts will know that it says all 4 names on the packaging. Of course this is assuming the US post was correct?

[shamtec25]

Well since my last post a lot has happened.

I went to pick my car up from Audi for a service and a cam belt change (£800+ [img]images/graemlins/062802beat_prv.gif[/img])

Got in the car and drove down the road with it stalling every time I pressed the clutch. So took it back to tell them I am now not able to drive it.

They have had it for another day only to tell me that it will cost around £3500 [img]images/graemlins/rocketwhore.gif[/img]

They reckon a new ABS control unit + a new ECU + a Airbag ECU and a couple of other parts. They say that this is due to someone at some time jumping it incorrectly and thus causing all this damage.

When I took the car to them I could drive it. Now it doesn't drive at all.

I have asked them to put the car in the same position it was when I left it with them. They reply that they can not without fixing the communication problem as this is how they would rectify the problem.

They will give me 10% off the bill for my inconvenience. What a joke.

I take my car there for a service then a cam belt change and to diagnose a warning light.

I walk away without a car and a 3 grand bill if I want then to fix it as it was when I dropped it off there.

I am absolutely livid. [img]images/graemlins/033102bad_1_prv.gif[/img]

My next point of call is to escalate this to their customer services team. Not sure what will happen then. But I am not giving up.

Any suggestions would be appreciated.

Cheers Lads

[jeffw]

I can't believe an Audi main dealer let you take a car away in that condition....did they not test drive it after they changed the belts ????

The first thing I would do is take the car away from the dealer and give it to someone who specialises in S4s as its obvious that your dealer is next to useless. AmD, Kim Collins at QST or Star Performance seem to be the popular ones....

[robscim]

Time to find a good lawyer!!

If the car was worse when you collected it than when you left it, they must have done something to it themselves. Maybe they jump started it incorrectly and caused the damage - it doesn't seem to be the problem you took it in with.

Firstly, get a good lawyer
Secondly, get onto Audi UK (they're based in Milton Keynes - let me know if you want some leads)
Thirdly, tell them you're going to go to Autoexpress (they used to do a great line in such disputed cases) [img]images/graemlins/24430-audibash.gif[/img] [img]images/graemlins/rocketwhore.gif[/img]
Forthly, but maybe should be first, don't go to Audi dealerships!!

How can such good cars have such [email]cr@p[/email] dealers? (And I used to work for the largest Japanese car maker - no wonder they do so well).

Rob

[img]images/graemlins/24430-audibash.gif[/img] [img]images/graemlins/rocketwhore.gif[/img]

[img]images/graemlins/yellows4.gif[/img]

[robscim]

Forgot to say, don't forget to remind them that they endangered your life by letting you take your car in an unsafe condition without warning you not to do so. [img]images/graemlins/rocketwhore.gif[/img]

[shamtec25]

Thanks for the reply Rob

I have now spoke to Audi customer service who belive it or not having spoke to the engineer at the Audi garage decided that they cant help me out and the matter is closed.

Have you got any names at Milton Keynes I could speak to ?

I have took my car away from the garage now and am looking for some cheap parts as I have found a Audi specialist near where I live who will do the work a lot cheaper than Audi.

Anyone know where I could source some cheapish Audi parts whether they be new or used. Or anyone breaking an S4?

My anger levels have reached an all time high. [img]images/graemlins/mad.gif[/img]

Cheers

Rob