ABS Warning Light Intermittent Fault

[Tonybolony]

Hi All.
This fault is beginning to annoy me- When turning Ign on from cold, the ABS light comes on, flickers, and stays on. If I turn Off and then On again (Before Starting Engine) the light usually goes off again, but more and more lately the only answer is to run the engine for a minute, then Stop and Re-start.
Very occasionally (as yesterday) the light comes on whilst driving.
I had a similar issue with my UR, which was down to a dirty terminal on the ABS pump power supply, but that isn't the case with the s2.
Any hints on what to look for regarding sensor issues, as I dont have the option at the mo of plugging her in to read faults.

[johne]

My guess is that your sensors must be working otherwise you get the light coming on all the time once you were on the move if one wasn't working or dropping out.

The before you move check is a continuity check which is the one you're failing so I'd check and remate each of the connectors where the sensors' wiring meets the loom inside each inner wing and also the ABS controller connector under the back seat.

I've experience of a failing battery giving ABS light issues but on a VW Corrado so don't know if it could apply to our cars.

John

[Tonybolony]

Hi John,
I had battery/supply voltage issues with my UR- the Combi Relay needs a certain voltage available to the pump before it will put the Warning Light out. I can understand this fault with the s2, but cant believe that the light can then re-illuminate whilst engine running, with the Alt putting out over 14v.

[johne]

Hi John,
I had battery/supply voltage issues with my UR- the Combi Relay needs a certain voltage available to the pump before it will put the Warning Light out. I can understand this fault with the s2, but cant believe that the light can then re-illuminate whilst engine running, with the Alt putting out over 14v.

I agree but in the Corrado's case the light was coming on when cold and ocassionally during running as well but a new battery solved the problem which was a heck of a lot cheaper than the cost of a new ABS ECU that the VW garage wanted to fit :corey:

John

[Tonybolony]

Thanks for the update John- I cant understand why the Alt can't provide sufficient voltage when running, regardless of battery condition, but Never say Never, eh?
I will try a new one and let you know.

[Tonybolony]

Sorry to bring this one up again, but it's cooking my Swede now!
When this fault originally started, it was intermittent, and more likely to happen with engine cold (Morning start), and poss battery voltage suspect. I changed the battery, and altho the fault didn't go away completely, it was somewhat better.
Now tho, I'm sure that Batt Voltage has nothing to do with it.
From cold, turn ign on, light flickers but stays on. Try this 2 or 3 times, and maybe light then goes out, but more often than not it will come on when the brakes are used (however gently). Sometimes the light will stay off for some considerable time, but maybe high road speed will bring it back on. It is getting worse as time goes on. I have a code reader available (would have to buy the leads to connect) but not sure if ABS codes can be read on S2? If not, what resistance readings would I expect to get from the sensor multi-plugs, assuming that's the next obvious place to check. Any other suggestions?

[Acidburn]

If you ever get up to swindon give me a shout and i'll let you the abs ecu, abs pump and a switch to try see if that cures your problem

[Tonybolony]

Cheers Acidburn,
If I can't figure it out myself, I might just take you up on that!