Bad brakes and fault code

[Oranoco]

Decided to take the A4 for a spin an the brakes feel awful with quite a hard pedal and little power. Scanned it and get a fault code saying the Abs unit can't communicate. Tried to clear the code but it just comes back up. Thought I noted the code but can't see it so will need to update later when I scan it again

Any ideas? Have a spare in my 99 donor car if it's compatible.

This is not what's wanted when I'm trying to go faster

 

[Oranoco]

Sitting here with a Snap On scanner and getting P1851 Data bus missing, missing message from ABS ecu.

Could this be the Golf ECU not talking to my Abs?

 

[Oranoco]

Might have this sussed, watch this space

 

[Andyb5tdi]

No idea, but fingers crossed for getting it fixed

 

[Oranoco]

Sadly couldn't prove my theory as the vacuum set up on the APU donor car is totally different.

 

[Andyb5tdi]

What are you thinking it is dude?

 

[Oranoco]

Don't think the servo is getting any vacuum as 1 way valve is stuffed. Pulled the pipe off while fiddling and found no pressure. VCDS is talking to the ABS module and says no faults, even ran through test sequences without a problem.

 

[Andyb5tdi]

Ah, shouldn't the vacuum be there even on idle though?

 

[Oranoco]

Yes it should but it just doesn't seem to be getting to the servo. The donor car hasn't run since April but there was still vacuum present when I popped the hose.

 

[aragorn]

Code is just a ghost from the new ecu.

You can bypass the one way valve for testing, just don't produce any boost.

 

[Oranoco]

Valve was dead and the hose had several hairline cracks on the concertina elbow. New pipe and valve on and it stands on its nose.