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A friend of mine has a audi a3 1.8 sport 1999 and the ABS light comes on occasionally, it always goes away again, she had a VAG diagnostic test done and the fault code was something like no power to abs brakes, so the garage who did it cleared the fault code and for a while it did not come on, then recently its starting to come on again, she wanted to know is there any common faults with ABS on audi A3's? or how to solve this problem? thanks in advance
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There is a nasty in the ABS ECU around that year; but her first check should be the three normal fuses in the distribution box on top of the battery - they corrode.
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Oh right thank you, ill get her to have a look soon, do you think if it was corroded fuses it would cause a intermittant light to come on?
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Sounds reasonable to me, a small amount of corrosion on a fuse could cause occasional loss of power to the ABS control unit.
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hi again, i have an update, we replaced all three fuses near the battery and then cleaned all the fuses in the fuse box to make sure it was not fuses, a few of them were a little corroded, anyway, did another diagnostic test but no fault codes were showing, she then drove it down the road and the abs light came on again, and then the red warning light with the exclamation mark inside it came on, she also said she has had problems with her hazard warning lights occasionally coming on and off? anyone know any suggestions as to what could be the problem? cheers
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Rather starts to look like the well-known solder joint issue with the ABS ECU. Get the fault-codes read to be sure.
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Rather starts to look like the well-known solder joint issue with the ABS ECU. Get the fault-codes read to be sure.
Hi thanks for your quick reply, there are no faults codes coming up on the diagnostic, and it was done with a VAG com reader? You say something about a well known solder joint issue with ABS ECU, what is this well known issue?
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If the light has been on, then there will be codes stored. Failure to communicate is a common sign of the solder-joint issue.
This needs experienced testing and assessment; any Bosch service centres nearby?
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me again! ... we have done yet another diagnostic test on it, the only code coming up is like ive said before is not enough power (or something like that) no other codes, someone has suggested replacing the battery as apparently Audi/VW dont perform well with old batteries but we dont want to fork out £60 if we are barking up wrong avenue? also someone else suggested brake pads worn out, would that cause ABS light to come on? im seeing her again tomorrow so any help would be gratefully received? cheers
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"Low voltage, terminal 30" codes are not usually caused by battery faults. That is why I suggested that this fault is now beyond DIY investigation.
Low brake pads won't cause that code either.
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Take a look at my thread : www.honestjohn.co.uk/forum/post/index.htm?t=66455
It required some minor disassembly but I've has no problems since.
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o.k thank-you guys, ive had a look at the link and it looks quite complicated, however it so happens my dad is a specialist in electronics, so maybe he could fix this without it having to be sent off, ill keep you updated with progress..... we cleaned the contacts today to see if that will make any difference so ill have to wait and see on that one, (brake pads front and rear look newish so dont think its that, anyway surely a fault code like ABS sensor would have come up on diagnostic instead of this low resistence one?) Do you know if we remove the ABS module, whether you can remove it without disturbing the hydrolic part and fluid etc? cheers natalie
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I'm not saying that your problem is identical to mine but it does sound similar. I assume that the A3 system is similar to a Passat of the same vintage. Yes you can remove the electronic part of the Passat Bosch ABS module without disturbing the hydraulics and the car is perfectly driveable (albeit without ABS). If you take a look at the BBA-Reman website, there's a bit of info about the problem. My soldering skills are pretty poor but if your father fancies a go, I mentioned a Russian website in my thread that details the fix required :
www.lbak.dk/Audi/Repair_ABS_unit_passat.pdf
in fairly understandable English. I was pretty impressed with the service from BBA-Reman but it did cost about £130 plus a couple of hours dismantling & reassembly.
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Can you verify what system of abs is fitted to this car?If I recall correctly ,the system is made by Ate and not Bosch.(same as Golf IV.)The diagnostic system and Vag-com should show which it is.hth
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Hi there, thanks for your replies, im not 100% sure what system it is, but it does look mighty similar to golf IV as luckily my dad has a golf mark 1V same year and we had a look at that module, almost exactly the same except the part number varies by one letter only? ... we have thought that maybe an idea would be to change the units around to see if it works in the audi, then we would know for sure whether it is the module? what do you guys think about that, is it possibe? or would the audi need some sort of reconfiguration?
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Hi there i can now confirm it is definately a Ate system, not bosch?
my friend says she is now getting another fault which is abit weird but could be linked, in that when she is driving at night with lights on, when she brakes the lights dip?
Has anyone heard of that?
(anyway tomorrow we are hoping to try and remove the ABS module and see what happens)
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Are the faults stored related to pump/motor/relay circuit?If this is the case then it is very probably a fault within the module.(usually dry solder joints).The module can be removed without disturbing the hydraulic system.It is held on by 4 torx screws(size #8 if I recall).However the control unit is a sealed unit and access to the circuit board needs some very carefull micro-surgery.Not sure what you mean by the lights dipping.Probably battery voltage dropping as the engine slows down?hth
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Yes the fault stored is a terminal 30 fault, low voltage and relates to braking system, we had a look today at all wheel sensors, but they seem fine, and anyway when we unlcipped the sensor the fault code would then be front abs sensor, so i think we can eliminate those, so i think it must be the module, we have now removed the module from the hydrolic pump, but like you say to get access to the circuit board do we have to now cut it open? or is this something best left to experts?
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This is the tricky bit.You will need to cut and remove a section of the plastic case directly behind the main terminal connector block and also the smaller connector behind the 2-pin pump plug.A small hacksaw or a rotary cutting tool (Dremel type)is the best idea but you need to be very very careful not to cut too deep otherwise the circuit board will be wrecked.With the circuit board exposed,close inspection should reveal dry solder joints on the pins,especially the 2-pin plug.Do you feel brave?If not give it to an expert.hth
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