RussAdams

Hi everyone,

I'm looking for advice on how to tackle finding and fixing a Haldex issue.

Ross-Tech VCDS Autoscan is showing an AWD/Haldex fault on my 2001 TT Quattro roadster. Autoscan results posted at the bottom.

I had all four wheels off the ground while doing a full brake job, and running the car in 2nd gear all four wheels move. Although applying the emergency brake does not bog down the engine.

Looking for suggestions on what steps to take to correct the error.

Thanks so much! Russ

Friday,28,January,2022,15:06:51:26743
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 21.9.0.2 (x64) HEX-V2 CB: 0.4555.4
Data version: 20210903 DS330.0
www.Ross-Tech.com
Mileage: 124260km-77211mi Repair Order:
Chassis Type: 8N - Audi TT (1999 > 2007)
Scan: 01 02 03 08 15 17 22 35 37 45 55 56 76 77
-------------------------------------------------------------------------------
Address 22: AWD Labels: 02D-900-554.lbl
Part No: 02D 900 554 D
Component: HALDEX LSC ECC 0011
VCID: 211CEDDD28DF6D7388F-4B00

1 Fault Found:
65535 - Internal Control Module Memory Error
00-00 - -

03_AR_CO

As I understand it, the controller is not functioning with that error. Several things to check, the connector and ground strap on the differential, if they check out the controller has gone bad.

RussAdams

Thanks!

It was suggested on another forum that you can test if it's actually working by doing a tight circle test. So yesterday I drove the car at 10kph in the tightest circle it will do and then coasted. It coasted for about 1/2 a circle. Then pulled fuse 31 and tried again and it coasted for a little over a full circle. So it appears it is working to some extent.

The car is going in today for a complete detailing, so I'll check the ground strap and connector tomorrow.

Does anyone know how to use Ross-tech VCDS to turn the Haldex pump on and off? I've been told you should be able to hear the pump run if it's OK.

Russ

03_AR_CO

Go with "Output Tests -03" scroll through there for different tests including pump (edited for clarity) Find "Output Tests" within the AWD Controller (22)

RussAdams

Thank you! I've only been using VCDS for about a year and I am challenged finding what it can do beyond basic autoscan.

You guys willing to answer questions are great!

Very helpful.

I'll give that a go.

J. Patterson

My 2001 coupe has had that same error code for several years. The Haldex seems to work normally however. Can turn off ESP and spin all four wheels in the wet. ( barely. Not enough power to really break them loose). I read somewhere in RossTech info that it is a glitch that does not necessarily affect performance. Sounds like yours is working too or you would have front wheel spin under hard acceleration and or binding and bucking when turning sharply.

RussAdams

Thanks for this. Helpful to know.

RussAdams

28 April 2022 update:


I tried the turning in a tight circle and coasting to a stop test. With fuse 31 in place the car coasted about 1/2 a turn. With fuse 31 pulled the car coasted over a full turn. I also tried spinning all 4 wheels in wet conditions with ESP off and did get all 4 to spin.

Two days ago I drained and re-filled all the drivetrain fluids. Rear differential, Haldex (and filter), and transmission. This is a 6 speed manual.

The car is running and shifting great after the fluid changes. I had the TT into an independent shop three years ago to change the Haldex fluid and filter... when I changed it two days ago the fluid looked pretty darn black. This is MAYBE 10,000 miles. I'm suspecting they didn't change either the fluid or the filter. See attached pix.

Thanks for all the help and pointers guys!

New fluid on left Old fluid on right

Lots of black in the filter as well as silvery-black goo.