ABS ECU Unreadable in VAG-COM

[MikeVR6 0]

The ABS light on my VR keeps coming on indicating a fault somewhere.

I used VAG-COM to try and read any faults. But it won't let me interogate the ABS ECU. It gives an error message basically saying the ECU isn't there! I can read the car's other modules (Engine ECU, Immobiliser) though.

I took it to a local BOSCH service center and their computer produced the same result. I also got them to check the ABS relays behind the dash and they are ok apparently. I bought a 2nd hand ABS ECU from E-Bay and tried that. Same result.

 

So, I'm a bit perplexed. The light comes on when I switch on the ignition. Then goes off after running it's startup check, the pedal does not "kick" though as I led to believe it should. Then normally the light comes on again after I start moving. Sometimes it doesn't come back on and this is when things get dangerous as it kicks in randomly when I brake, the pedal judders and the pump makes strange noises.

Tempted to rip the whole damn thing out. But I am by no means a mechanic so I'd have to pay someone to do this.

 

Really need to get this fixed as the car is due MOT soon and this will certainly result in a FAIL. :(

[Timbo 0]

viewtopic.php?p=816919#p816919

[MikeVR6 0]

Hi Timbo yeah I read that thread.

When I first purchased VAG-COM I had to fiddle with the COM port latency settings to get the ABS unit to connect. Back then the ABS was fine.

Now, it won't even connect with the "real" diagnostic computer in the Bosch dealers.

 

Looks like I may have a ribbon cable problem too. Nightmare!

 

Anyone else have a suggestion?

[shamstar 0]

Take the bulb out for the MOT....then get it fixed....have you tried another ABS ecu.....they have a dendancy to die when the car has been stood for a while....

[Critical_Mass 10]

Unfortunately taking the bulb out wont work on the MOT tester... unless he's stupid. If ABS is fitted to the car the light must work.

[MikeVR6 0]

Unfortunately not. That's why I suggested ripping the whole darn lot out.

Believe it or not, the quality of VW Specialists here in Germany leaves a lot be be desired.

Think I may have to bring the car back to the UK and have a real specialist look at it.

[Supercharged 2]

You might find it's worth a trip to the dealer mate - the 1551 might read it when the Bosch / Snap-On ones don't connect.

 

Sounds like a valve block issue if the light is going out but no system pressure test at 5 mph - Like you say it could well be breakdown of the ribbon cable but not sure if this would stop the diagnostics connecting or not...

[g0ldf1ng3r 15]

if i recall correctly - or along the right lines - when my parents had their 2l rado their ABS light came on intermittently

i believe the issue was due to the location VW chose for the ABS ECU as the box/contacts get wet

the garage knew an electrician who replaced the connections - or something like that

maybe it might point you in the direction

does any1 know of anything similar as my ABS light is intermittent too lol

other than that they used to do as previously suggested and remove the bulb - a good relationship with the MOT'er might be necessary tho :)

[MikeVR6 0]

Thanks for the tips. There's a VW Stealership near me so I'll call in and see if they can run a quick check.

 

I'd rather get the problem sorted as ABS is handy to have in the winter months.