Help with power steering ABS and speedo
 

Ok.. so I have read about this on the American forums but still there is no solution..

My LWB D3 4.2 will act normal and then in slow moving traffic the esp light will come on along with ABS light.. while this happenes the speedo stops working and the power steering goes either very light .. or turns off and goes very hard.. also lift mode in the car mmi is greyed out and dose not work.. it also sound's like the compressor just goes flat out during this period..

If I leave the car to cool down it all works as normal again .. over night the same its perfect .. and if I get in while its cold and get on the motorway it will be fine for hundreds of miles ..

But as soon as I slow down to city traffic speeds . Boom it all goes hay wire ..

Now a VCDS Scan reviled that the passenger side front abs sensor was at fault ..
So I replaced it and .. nada .. still the same as before..

Its intermittent but getting more frequent now and very irritating and embarrassing if some one is in the car

Has any one ever had this before ? Or known of a solution to this. . Ive tryed all sorts ..

Ive unplugged the abs module and sprayed with wd40 .. nothing
Ive checked with an oscilloscope to see if each wheel is picking up signal from the abs sensors (also speed sensors on d3 ) and interestingly there all fine when you rotate each wheel you can see on the screen its picking up signal.. however the passenger side front dose not pick up signal when this fault occurred


dose any of this make sense ? Or any one know what to check next ?


Real bug bearer now

Thanks Guys

Loose connection, broken wire for passenger front sensor or dry solder joint inside ABS/ESP controller.

Hmm ok so how do I fix that ? Strip the Abs module ?

This is a hell of a challenge.
My mate has similar problem with ABS and ESP lights coming on while breaking and steering the wheels, sometimes its fine for days, sometimes it just wont go off.
Still issue is unresolved. Tried new brake switch, nothing, checked all the connections but he never got a abs sensor fault.
Plus his car can loose some power as he was getting a solenoid valve dtc on his gearbox.
Really complicated fault.

His is a 4.2tdi.

Was ABS sensor the only fault you got?? If yes then I would start from properly investigating all the connections to that sensor especially.

I cant answer this one, but as a thought, does the fault occur because you slow down, or because you hit the city and start turning sharper - Sharper turns will put larger differences between the two front ABS sensors in terms of speed, and will also stress the steering wheel sensor more to the limits of its calibration. If something wern't calibrated quite right, it could have a fit and think you're skidding out of control when you're not.

If however it happens in a completely straight line, but at slower speeds then I have few ideas other than something possibly temperature related with the lower airflows, or an issue with the air suspension trying to pump back up at lower speeds when you've stopped cruising at the higher speeds....

I guess the big question is - exactly what are you doing when it happens, and is it consistent.....?

DTCs he is getting with a very similar problem to yours.
Tried calibration. Sometimes it's fine for days but one run over rail track and abs and esp kicks in instantly which indicates some connection problem.

Address 02: Auto Trans Labels: 09E-927-156.lbl
Part No SW: 4E1 910 156 S HW: 09E 927 156 B
Component: AG6 09E 4,2 TDI RdW 0010
Revision: --H01--- Serial number: 0096931
Coding: 0000001
Shop #: WSC 02313 785 00200
VCID: 3365F05952BA9686591-8066

2 Faults Found:
006231 - Load Signal
P1857 - 001 - Error Message from ECU - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 0
Fault Frequency: 254
Reset counter: 255
Mileage: 191879 km
Time Indication: 0
Date: 2013.10.05
Time: 13:15:08

Freeze Frame:
RPM: 1984 /min
RPM: 1952 /min
RPM: 2848 /min
(no units): 70.0
(no units): 31.0
Temperature: 40.0°C
T.B. Angle: 26.3°

001923 - Shift Monitoring
P0783 - 000 - 3-4 Shift - Intermittent
Freeze Frame:
Fault Status: 00110000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 195897 km
Time Indication: 0
Date: 2013.11.09
Time: 19:51:52


-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 4E0-910-517.lbl
Part No SW: 4E0 910 517 B HW: 4E0 614 517 BC
Component: ESP 5.7 allrad H46 0510
Coding: 0008557
Shop #: WSC 02313 000 00000
VCID: 224B051DFD400F0EA27-8077

3 Faults Found:
00003 - Control Module
014 - Defective
00778 - Steering Angle Sensor (G85)
008 - Implausible Signal - Intermittent
18265 - Load Signal
P1857 - 000 - Error Message from ECU - Intermittent

Implausible reading from steering angle sensor will seriously screw things up for sure. It'd be worth popping a replacement one on and recalibrating to see if it helps imo.....

If the steering wheel has ever been off, its quite possible the slip ring wasn't put back on at the right rotation, that causes all sorts of weird stuff, even when calibrated.

mine seems to happen when in slow moving traffic. if im on the motorway it will be fine ..

and then for example if i stop at a services to park it will kick in and i get ABS and ESP light ..

and like i said the steering either goes very hard or it goes very light and also lift is grayed out on the MMI and when it happens it makes the compressor for the air suspension just go non stop

when you use scopes in vac com you can take a reading off each abs sensor

and everything works fine ... but then when the fault occurs it seems to loose signal from the passenger side Abs sensor.
i was going to check the ring but it seems its built into the wheel bearing on the A8 ?

i would really welcome any help im struggling so much with this to the point i really almost want to scrap the car or strip it for parts ive had enough of it now its embarrassing its noisy its dam hard to steer when it happens and ive just lost it with it ... the pleasure of driving it has gone :(

It will be the abs/esp module. I had the exact same thing- sent the unit in for remanufacture and never came back since. It's possible to get the module off from the abs pump without removing any of the brake lines, but it's pita to reach 2 of the torx screws. Should disconnect the battery before disconnecting the unit.
I've used them - actronics

Thanks +++ I will try that then and see if it fixes it