ABS - ecu codes?

[Christophski]

Hey guys, wondering if anyone can help?

Over the last month and a bit my avants abs seems to be kicking in every briefly now and then when braking gently but the light on the dash doesn't come on. (The light does work as it lights when I turn the ignition)

Question is, if I read the codes, will the ecu tell me if its a faulty and sensor and of so which one it is? Or is it just going to say check the and sensors leaving me to figure out which it is? If this is the case any pointers on how to check which one is faulty?

Thanks in advance for any guidance

[UrS4boy]

VAG-com and ABS fault codes

VAG-com or something like Ross-Tech VCDS can tell you which sensor is causing the problem, etc.

Example: http://wiki.ross-tech.com/wiki/index.php/00283

[domas]

naah.

if the abs system misbehaves and does not kill itself, it means that it does not recognize the fault. If it just unwanted abs pump operation when braking just before stopping - it is a typical symptom of low signal from one of the sensors.

So you will have to check measuring blocks when driving slowly in a straight line to see which wheel differs from others.

This is a typical ABS diagnostic procedure

[RichLV]

Unless you have a pre-1993 model year car, in which case ABS unit is not connected to the OBD system, like in my 1992 UrS4. :/ In that case only guessing or checking via oscilloscope will tell you about the state of the sensors.

[domas]

it was not only year dependent, model as well.

1987 Audi 80 with automatic transmission had vcds interface for abs while c3 chassis cars got it way later. IIRC manual c3 cars never got it.

then you need vag 1710 / kdas 0003.
I have one, it was a life saver for few of my mates

[GazzaG60]

so if say on my car a b3 with vems. if the abs light comes on is it a manual fault find?

[domas]

year, transmission manual, fwd/quattro?

[domas]

else just check if pin 31 is present at ecu under rear seat. that is obd pin

[GazzaG60]

1991 manual quattro.
i got an abs light on after about 100m.chances are its due to me changing everything on the car, hubs, shafts etc on the change. rather than have to strip check and clean each corner. it would be nice to know where its triggered from.

i run vems. i have the 2 obd connectors from the s2 loom there but i have vems pnp and 1991 abs.

sorry to hi-jack a little chris.

how

[Mikes2]

for a quick and easy check, disconnect each sensor and measure the resistance. should be around 1200 ohms

[domas]

gazza, find someone with oscilloscope.

if the light comes on later, it is not likely to be sensor per se fault (resistance)
it is the distance to the ring issue most likely... or number of teeth on the axle

[Christophski]

VAG-com or something like Ross-Tech VCDS can tell you which sensor is causing the problem, etc.

Example: http://wiki.ross-tech.com/wiki/index.php/00283

Excellent thank you for the insight. Will try get my brothers scanner on it and hope it reads.

Thanks for all the pointers guys