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Haldex not working? No communication etc? Look inside

Discussion in 'A3/S3 Forum (8L Chassis)' started by badger5, Dec 16, 2011.

  1. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Dec 16, 2011]
    If you have Haldex issues...
    check out these pictures of an S3 in here yesterday with only fwd

    Usual Earth strap broken and very corroded generally around the fixing..
    [​IMG]
    Fixed by making up a new earth lead and replacing it.

    Also... Check connectors for corroded pins..
    [​IMG]
    [​IMG]
    [​IMG]

    Replacing both pin and socket in connector, with vag repair replacements, and the haldex pump started to work again and 4wd was once again working again.

    cheers
    bill
    #1
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  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 16, 2011]
    Bill are you able to get a picture or give a description of where the earth strap is on the Haldex unit. Every time i've been under my car and looked for it I can never see it!
    #2
  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Dec 16, 2011]
    Added to FAQ stickies....

    <tuffty/>
    #3
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  5. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Dec 16, 2011]
    this picture is take on passenger side viewed just fwd of the drive shaft.
    bolt/strap are about at the 11 o'clock position and go up to a stud on the floorpan, which may also shear off when you look at it. It can get very corroded down there.
    The plug connection is on the back of the diff, usually behind a small ally heatshield.. just in front of the rear silencer

    [​IMG]


    hope this helps
    regards
    bill
    #4
  6. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 16, 2011]
    I'm woring on TQS tonight so I'll have a little look. cheers.
    #5
  7. jay 400
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    jay 400 New Member

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    [Dec 17, 2011]
    Thanks bill my cars running great now !
    #6
  8. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 17, 2011]
    I spotted it last night, thanks Bill. It seemed quite fresh on the car I was under. Possible been replaced before.
    #7
  9. Muggi Dee™
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    Muggi Dee™ Major Petrol Head

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    [Jan 13, 2012]
    Does this fix work if there is a 'humming sound' from the unit when you turn it off? Or does the sound represent complete death?!
    #8
  10. k1ano
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    k1ano Member

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    [Jun 16, 2012]
    I found my earth strap was broken today when I was checking the rear xenon level switch. I did have intermittent output communication errors but interestingly enough no warning lights or other symptoms and the 4wd was definately working last week on a muddy field - I have repaired the strap anyway ...

    Martin
    #9
  11. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Nov 6, 2012]
    #10
  12. Nilz
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    Nilz Defo worth the wait :)

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    [Nov 6, 2012]
    Hey Paul

    Im sure you have come across the other trhead about the 'dragging' wheels, do you know of or is Bill aware of anything that could be causing this, there are quite a few people that are having this issue, including me, so would be good if an 'expert' ;) could give a view or some advise on this or even a possible solution :)

    Cheers
    Nilz
    #11
  13. phil miller
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    phil miller Member

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    [Nov 6, 2012]
    good bit of info there, and easy to follow pictures
    #12
  14. Was
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    Was Member

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    [Nov 7, 2012]
    Hi - I have the dragging wheels, and had to take fuse out to get the car back into two wheel drive mode. this has been really annoying me but every gargage I talk to seem to think they know what the problem is, but seem to want to charge through the roof to invesitgate. Have changed the Haldex controller, and complete a number of tests.

    1. Driving along and pulling handbrake up - this dis-engages the haldex and drives, put hand brake back on haldex engages but wheels make a noise.
    2. Pulling away in second gear - no haldex enagaged, front wheels slip and it engages and rear wheels start to lock (sound like they are)


    Seems the haldex is confused and tries to engage at the wrong time.

    Bill - I live in Orpington, kent, if you know anyone down this way you trust I can take my car to then please let me know. I had an ex Audi guy look at it and he noticed a grey tint to the Haldex oil, and stated the haldex was broke, before I spend any money on it I really want to know the fix, if its a new rear diff then great, if its not then I could be out of pocket £200 plus and still have the problem.
    #13
  15. jitvv
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    jitvv Active Member

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    [Nov 11, 2012]
    On my First S3 (7 years ago now.... ) i had a similar problem with the rear wheels dragging, it went to a number of different garages including a Stealers i replaced the controller, the diff still the same problem mine turned out to be the ABS ECU that was at fault, mine had no fault codes or error lights. a local VAG specialist fixed mine.
    #14
  16. thegoal007
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    thegoal007 Another S3 owner....

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    [Nov 11, 2012]
    As a matter of interest, did you try removing the haldex fuse and did the problem go away ?. Handbrake trick ?

    your the guy who replied to me with that information when I asked you 4 years ago ! When I was reading into this issue as much as possible.

    The only thing I have to add is that with the knowledge I have built up surrounding this issue nearly all reports of this problem were solved by simply swapping out the complete rear end rather than messing around with individual components. YOU are the only one I have read that it was the ABS/ECU unit. But it's a possibility as it too communicates with the Haldex - i gather the abs unit also handles the ESP function (?)

    The other thing, and call me skeptical but were ALL the parts replaced on your car with NEW or reconditioned parts before replacing the ABS unit ? And was the ABS unit new or reconditioned your old one ? I'm just thinking there may have been an issues somewhere with an earlier part which was replaced and they sold you the abs unit and fixed something minor (maybe!) just to justify it - after all that ABS unit is a fairly expensive part ! - I did say I was skeptical :)
    Last edited: Nov 11, 2012
    #15
  17. Erf
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    Erf Member

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    [Nov 11, 2012]
    Bill as Was said, I'd be happy to travel to Gloucester to get mine fixed! I've replaced the rear diff, the haldex pre charge pump, oil and filter change, front wheel speed senors and spent money on 'investigative' work.

    Incidentally, the only error code I have is on my front driver's wheel speed senor, inspite of having it replaced. My local mechanics have looked into the electricals and they don't believe there is anything wrong with the loom. They did suggest either replacing the front wheel speed sensor again or that it could possibly be the abs ecu.

    Currently I have fuse 31 out and therefore have the esp light on. If I brake hard, my abs light goes on too.

    Any help would be appreciated!
    #16
  18. Was
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    Was Member

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    [Nov 12, 2012]
    note I have a 2005 2.0T quattro, so high jacking this forum a little. But like you Erf I have the fuse out so I can use my car. At the weekend I did the following:

    Handbrake test - Haldex goes off, with it on it drags the wheels
    Left foot braking test - this had not affect
    Next test is to test power from ECU to ensure its getting to the back wheel, which I assume it is, but then I can isolate the issue to the rear.

    The car did however pull away fine, and I had to spin the front wheels to engage the Haldex to work. Its like the Haldex is going on but then not releasing, therefore thinking the front wheels are spinning when they are not.
    #17
  19. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Nov 13, 2012]
    Dunno why but always assumed haldex in these cars didnt talk to VCDS hence the no communication during fault scans.

    Anyway spotted this thread a few days ago and managed to get round to checking mine out yesterday. After a bit of faffing about looking for said earth starp i spotted it and it looked ok as was attached at both ends. But i thought i would give it a quick wiggle just to make sure and lo and behold it fell away from one side and was very old and brittle.

    I went to undo the other end of the strap which connects to the shell of the car and rather than undo it just pulled straight off the car leaving a nice hole lol.

    So i have done my best pikey magyver fix as i didnt have a replacement strap i found some of the really old mains cable that has 3 thick copper wires in it in my dads garage. So i stripped the ends and wrapped it round the bolt and bolted back into the haldex. cut the mains to the right length and made a new earthing point where the rear headlight adjuster bracket sits.

    Gave my car a scan today and lo and behold VCDS talks to haldex and it did have a minor fault lodged in its brain so have no cleared that too and re-scanned with no faults :)

    once again ASN and its members help again and let me fix a fault i never knew i had and would never of worked out on my own especially for the grand total of £0!!
    #18
  20. Lavis89
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    Lavis89 Active Member

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    [Apr 15, 2013]
    this is definitely reviving a dead thread but may be of use to people. i've had haldex problems for approx 6 months, whenever creeping on the clutch and trying to turn (whilst parking up for example) or even with a small amount of acceleration it made a horrible noise, could never quite work out if it was a grinding noise or the wheels being dragged around. i had tuffty suggest to me in another thread to get the haldex unit serviced. Got the unit serviced last week (and met mr miller in the process)

    IT WORKS! all grinding/dragging noises are gone, and i dont know if it is just me but it feels so much smoother when cornering at speed now.
    #19
  21. peterjacks84
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    peterjacks84 New Member

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    [Mar 17, 2014]
    Ive recently been told by local vag specialists that my 2001 s3 AMK does not have an earth strap for the haldex, can anyone confirm this as true?

    I've also recently sorted the dragging wheels issue by changing the haldex oil and filter, all for 65 odd quid from eBay

    Cheers
    #20
  22. rupe
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    rupe A3 TQS

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    [Mar 18, 2014]
    my 2001 a3 quattro doesn't have one either and never has done as the stud on the floor pan where it would attach is all covered in the underbody stuff.So shouldn't be anything to worry about, but could fit one I guess if you were bothered about it.
    #21
  23. peterjacks84
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    peterjacks84 New Member

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    [Mar 18, 2014]
    Ok cheers just wanted a second opinion before buying a new haldex unit, have a no comms fault and have read a lot about missing or broken earth connector being a common problem and quick fix.
    New unit it is then

    Cheers
    #22
  24. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Mar 18, 2014]
    My 2001 AMK had a strap that was broken... I replaced it with a short bit of battery ground cable I bought from halfrauds

    <tuffty/>
    #23
  25. Nilz
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    Nilz Defo worth the wait :)

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    [Mar 18, 2014]
    My 2002 AMK had a earth strap that was broken and has been replace, but I still have the issue on mine.
    #24
  26. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Mar 18, 2014]
    Last car I saw with the dragging issue was down to a faulty controller... pull the haldex fuse and see if the dragging goes... if it does then chances are its a controller issue

    <tuffty/>
    #25
  27. Vex182
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    Vex182 Guess what I drive...

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    [Mar 18, 2014]
    My haldex has always been fine but I found the earth strap broken about 6 months ago and just changed it with a battery negative strap from Halfords. There had been no issue anyway with it broken on mine.
    #26
  28. peterjacks84
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    peterjacks84 New Member

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    [Mar 18, 2014]
    I have esp light on over 15mph, the dragging has been resolved by servicing the diff (haldex oil and filter) but light still on (no comms). I'm a little confused over why some have it and some don't. I've read quite a bit about faulty/missing earth link being a major cause of the no comms fault. I just wanted to eliminate all the cheap options before buying a new controller.
    Thanks for your help chaps
    #27
  29. Nilz
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    Nilz Defo worth the wait :)

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    [Mar 18, 2014]
    Paul ive removed the fuse on mine and still have the same issue!!

    Looks like it may be a replacement controller.
    #28
  30. russwuss
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    russwuss Active Member

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    [Mar 18, 2014]
    My 2001 AMK had the earth strap and was also snapped causing the dragging wheels issue.

    Made an earth strap and still wasn't working correctly, looked at the connector.. when I pressed it together than haldex came on (tested with vagcom) soon as I let it go it wouldn't communicate.. Fixed it by forcing the connector together with cable ties :jester:
    #29
  31. jay22s3
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    jay22s3 2nd gear sorts em out

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    [Mar 18, 2014]
    where would this dragging noise come from front or rear ?
    #30
  32. Nilz
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    Nilz Defo worth the wait :)

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    [Mar 19, 2014]
    From the back, but you can hear noise from the front too....well you can on mine if you are on full lock.
    #31
  33. Jenno007
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    Jenno007 Member

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    [Sep 12, 2014]
    Since this is the Haldex thread that is referred to in the stickies I figure I may as well post here so it can help people in the future (if someone manages to answer my question).

    My haldex is on constant 4wd (even with the fuse pulled and/or the handbrake on). This makes tight cornering (especially parking) a nightmare.

    The haldex has recently been serviced and has plenty of oil.

    Are there any steps I can do to try figure out what is causing this? I would prefer to give it my all before I pay someone to do it. Thanks
    #32
  34. rupe
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    rupe A3 TQS

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    [Sep 12, 2014]
    #33
  35. Jenno007
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    Jenno007 Member

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    [Sep 13, 2014 at 10:20 AM]
    I've seen that thread. I'm really hoping it is something more simple than that. I was wondering if anyone had any tests I could to do see if it is the pump etc.

    Thanks for the reply though
    #34
  36. rupe
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    rupe A3 TQS

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    [Sep 13, 2014 at 11:21 AM]
    If you have pulled the fuse, then the pump won't be running and the diff can't lock. Check to make sure your pulling the right fuse out, do the abs and esp lights come on the dash when you take the fuse out? or another way to be certain it's mechanical rather than an electrical fault, disconnect the plug at the rear of the diff, this will disconnect the power going to the haldex controller and the pre charge pump.

    [​IMG]
    #35
  37. Jenno007
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    Jenno007 Member

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    [Sep 13, 2014 at 11:23 AM]
    Quite sure I pulled the correct fuse. I will disconnect the plug. Thanks for the tip. If I disconnect the plug and it's still 4wd I'm guessing signs aren't good?
    #36

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