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Haldex system confusion

Discussion in 'A3/S3 Forum (8L Chassis)' started by S3LOUD, Feb 9, 2012.

  1. S3LOUD
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    S3LOUD Member

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    [May 16, 2012]
    Okay little update. I put the car on the ramp, had a look and saw that the earth strap was actually snapped. Sighhh of relief when i saw it so stripped the wire back and bolted put it directly onto the earthing spot and used the metal piece to hold it down tightly. Put the haldex fuse back in, took it for a spin only to find out the issue was still there :(. Plugged it into a launch system and ran the haldex checks again but issue is still there.

    Cheers for the link tuffty I just checked through it and im going to have a look at that connector today and see if thats causing the issue. Hopefully *fingers crossed* that could be the issue and i could put this haldex issue to rest lol.

    Once again thanks a lot for all the help!! :D
    #81
  2. jezzy
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    jezzy Member

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    [May 16, 2012]
    if the plug has oil in it your pump seals have gone, new pump time
    #82
  3. k1ano
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    k1ano Member

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    [May 16, 2012]
    Been thinking about this a bit more ...

    The rear diff in the Haldex is open so should not drag unless it is broken but I assumed that if the Haldex was not working it would fall into a fail-safe mode of clutch dis-engagement. If however the Haldex clutch is engaged (though error codes presumably would show) then you would effectively have no centre diff and so no differential speed between front and rear axles and so a cornering impact would be detected.

    Here is a quick note on the scenario which could be explored also perhaps ...

    <snipped from Four-Wheel-Drive Systems Demystified - MSN Autos>
    Since the part-time system has no center differential, there is no way for the two axles to rotate at different speeds in a corner. So, part-time systems shouldn't be engaged unless the vehicle is on very slippery road conditions such as deep snow and mud where wheels can slip as necessary for turning.

    If you try driving one of these vehicles on dry pavement with four-wheel drive activated, you will likely feel an awkward, binding sense as you turn a corner. It's also possible to damage drive system components on these vehicles and cause premature tire wear if you travel in four-wheel drive on dry pavement.
    <snip>

    Personally I am used to AWD systems utilising viscous centre diffs and torsen rear diffs which avoid any of the quirks of 4WD which I am learning about with these Haldex thingamejigs. So for now, this excludes me thinking about a 'blue' Haldex controller, which I had been considering, as I don't really want 4WD engaged unecessarily as I am sure this would result in slighlty unpredicatable behaviour which would take some 'learning' LOL

    Martin
    Last edited: May 16, 2012
    #83
  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [May 16, 2012]
    It will be dragging if the clutch plates have welded together or damaged enough that the normal clearance is compromised so the plates catch or the pump is not operating as it should and applying a degree of pressure to force the plates together...#

    Removing the fuse should allow conformation of a mechanical failure of the plates as it should still drag if the plates are binding for whatever reason... another test could be to drive with the handbrake engaged enough for the light to come on and thus prevent the haldex from being engaged when it normally would be (operational failsafe) but should leave it in its normal prepared state (pump/controller active)...

    This of course is based on my understanding of how Haldex operates rather than actual experience... not seen enough of these myself yet to comment but in theory I believe the above to be correct..

    This explains (to me at least) why sometimes an oil/filer change fixes the issues on some cars and not others...

    <tuffty/>
    #84
  5. k1ano
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    k1ano Member

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    [May 16, 2012]
    Makes sense to me in theory too ...

    The issue with having no centre diff and engaged rear drive, as may be the case here, is that other transmission issues will manifest eventually which could result in more major failures.

    Another suggestion, which is more work, would be to remove the prop shaft and see if the drag dissappears - this will confirm the whole Haldex unit is at fault and also protect the transmission until it can be relaced. The rear diff, assuming it is OK, should still allow differential rear wheel speeds and the dragging should stop. If dragging still occurs it will be the diff itself and NOT the Haldex clutch.

    I remember taking my old Mazda 323 4x4 Turbo to a Mazda dealer for some work many years ago and they engaged the centre diff lock by accident. They phoned me up and told me my gearbox was faulty - when I questioned them more for symptoms, they couldn't turn the car in the workshop without scrubbing the tyres. I asked them if the center diff lock button was depressed and the light on - they said yes, then turned it off and 'hey presto' the faulty gearbox was no longer faulty !!

    Martin
    Last edited: May 16, 2012
    #85
  6. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    [May 16, 2012]
    This tells me its not your diff or the mechanical condition of the haldex clutch plates, otherwise how would the removal of a fuse change the physical condition of the diff/clutch plates? If it's not wiring/connector or the earth strap i'd be looking at the controller or the pre-charge pump....and just because Vagcom doesn't throw a fault it doesn't mean there isn't one, my didn't throw a vagcom fault.

    As posted earlier this is worth a read: http://www.billswebspace.com/HALDEX.pdf
    #86
  7. S3LOUD
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    S3LOUD Member

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    [May 21, 2012]
    okay so just a little updatee. Unfortunately bew the gearbox in my car this week so cars in the garage getting repaired. About to be stung for around £700 not including the clutch :( which im going to have to do aswell seening as the box is coming out. As soon as i get her back i'll check the diff plug and see if thats what caused the dragging and let you all know :).
    #87
  8. Erf
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    Erf Member

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    [May 21, 2012]
    My money is on the pre-charge pump...
    #88
  9. thegoal007
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    thegoal007 Another S3 owner....

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    [May 22, 2012]
    That might be a difficult one to explain. Remember S3LOUD said removing the fuse cured his problem. Not quite sure on your logic. unless he ends up with 2 problems !
    #89
  10. jezzy
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    jezzy Member

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    [May 22, 2012]
    ive just changed my pre charge pump, it takes about 30 mins to do an is quite easy.
    two small hex screws and use a screw driver to move the rubber dognut on the drive shaft over.
    The pump was burnt out and you could smell the burning as soon as it came off the car.
    My issue was intermittent, awd sometimes and oil in the little plug on the rear diff.
    today little spin around the back roads no wheel spin, so awd back.
    I have read extensively on the subject, usually bad electricals(first check) pump second and third haldex(being the most expensive)
    im no expert but a little time and reading will usually solve the issues your having.
    i personally would not swap the whole back end, you could be getting the same problem with another unit and never resolve your issue. but thats just imo.
    good luck and i hope you solve awd issue
    #90
  11. S3LOUD
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    S3LOUD Member

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    [Jun 5, 2012]
    yeahh i know. I was very new to all of this when i first got my car and stupidly gave it to audi to diagnose. They were the ones who said it was either the clutch or the controller so i changed both and still did nothing. Cars finally back :D... after a total of £930 for the gearbox and new clutch X_x, butt means that i can check the diff plug tomorrow to see for any corrosion and hopeee for the best that its the end of all of this locking up! lol.
    Thanks for sticking with it lads and should hopefully be back tomorrow with an update ;)
    #91
  12. Nilz
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    Nilz Defo worth the wait :)

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    [Jun 7, 2012]
    Watching this thread, as im having this issue as well!!

    I have recently had a haldex oil and filter change, however the issue still occurs!!

    I havent had a chance to check the earth strap, but will have a look at that when the weather clears up a bit.
    #92
  13. thegoal007
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    thegoal007 Another S3 owner....

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    [Jun 8, 2012]
    you maybe looking at this thread closely, you might just want to read all the the comments S3loud has made on what he has tried so far and make sure you experienced the same before following too closely. For example when he removes the haldex fuse (31) his problem appears cured - does yours ?
    #93
  14. thegoal007
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    thegoal007 Another S3 owner....

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    [Jun 8, 2012]
    i can understand your thinking on the controller possibility based on the results, but not the pump - even if ERF too has mentioned this. How is removing the haldex fuse a possible indicator the pump has failed ? Does the same fuse control the pump ? And would this be cause of the problem - i.e on full lock (right or left) the rear wheels appear to be locked ? Surely there is a sensor involved otherwise why doesn't it do it all the time....I may be wrong, but not sure of job of this pump and results when not working.
    #94
  15. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    [Jun 8, 2012]
    I only mention the pump as, from reading on't t'internet, it seems like one of the main culprits when other people have experienced the dragging problem, but have ruled out the oil/filter/earth strap etc.

    Does the pump use the same fuse? I don't know, just a guess.

    Could a faulty pump be causing the problem? I suppose it could if the failure caused the pump to constantly be on when the ignition was on, as this would lock the system in 4WD but the dragging would only be felt on tight lock, it'd be unnoticeable the rest of the time.

    Electrcial gremlins cause wierd sh1t to happen, I know, I own a Peugeot as well!
    #95
  16. S3LOUD
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    S3LOUD Member

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    [Jun 8, 2012]
    Okay so this is the latest. Checked the plug going into the rear diff with high hopes to see corrosion...
    take a look... and its probably the cleanest part of my whole car :| lol. No corrosion of any sorts what so ever.
    I took the earthing strap off once again and cleaned the earthing point in the hopes that it could be a bad connection however took the car out and dragging issues still there :'(.
    Now this is something i was a bit confused of. After testing the car i turned it off, pulled out fuse 31, took it for a drive straight away and the issue was still there... turned the car off and put the fuse back in as had to go somewhere.
    When i cam back i took the fuse back out and parked the car up for an hour or so. I then took it out for a drive and the issue had magically disappeared... Could this be that the car continued to drag the first time after removing the fuse because the car literally had no time to rest between tests??
    A bit confused and really getting tired of this issue :(!
    As always thanks a lot for the help everyone! its much appreciated :D!

    Aaron
    #96
  17. murran
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    murran Active Member

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    [Jun 8, 2012]
    leave the fuse out for a few days/a week..... if its fine with no reacurances, then with the ignition off put the fuse back in, put the ignition on, clear any fault codes you might have caused..... on the first or second drive is the dragging is now there?
    #97
  18. thegoal007
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    thegoal007 Another S3 owner....

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    [Jun 8, 2012]
    sorry to point this out, but re-read what I have already mentioned in note #76 above - last paragraph.

    All I can tell you is every time I start my car, I plug the old laptop in and go through the output test I have already mentioned here (with engine running) and then remove laptop and drive off without issue. I know this solves it because as I turn out of my garage a hard right or left I feel the dragging so I just plug the laptop in at that point and do the test and it's cured.....every time ! Ok, a couple of occasions I ran it twice.
    As I have also already mentioned, occasionally as I turn out of the garage I find the problem is not there - again read note #52 - 2nd paragraph !

    What might also be pointing to the pre-charge pump is the fact:
    1. no noises when running through the pre-charge test
    2. problem is cured as I cycle through the tests - which attempts to switch on and off the pump.

    Although still not 100% it's the pump because it could be the controller for the pump not doing it's job - if that is controlling it- because by running through the test maybe your forcing the controller or pump to go on and off......who knows how these things really work ?
    Last edited: Jun 8, 2012
    #98
  19. S3LOUD
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    S3LOUD Member

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    [Jun 11, 2012]
    Yeah i read those but to be honest i dont fully 100% understand what you mean by them. I replaced the controller pump for one that was 100% working so i kn ow thats not at fault. The only thing now would mean possibly is the pre charge pump??? But then back to the point that removing the fuse means the noise no longer occurs.
    Ahhhh this cars soooo confusinggg lol.

    Anyone have any suggestions of what i should possibly try next as a test? I'll try removing the fuse for a few days and see what happens and just hope that fixes it lol but for now any other suggestions???
    Thanks again lads!
    #99
  20. thegoal007
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    thegoal007 Another S3 owner....

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    [Jun 11, 2012]
    controller pump & pre-charge pump is that not one and the same thing ?
    Do you actually have vcd software & cable? Check you can communicate with the haldex, and charge the pump and engage and dissengage it. When doing these test you should hear the pump. If you have a pump that is definitely working then it should make a noise.
    let me explain again how to actually run this test: Quote from post #28....
    in vcd control module selection screen. pick 22-AWD and then select output tests - 3 and hit start/next. This will go through putting the precharge pump on and off and the awd clutch off/on. When the precharge pump is on it should make a noise. Obviously with the ignition on only.

    And what I was saying in my previous post was that when I do the same test whilst the engine is running it seems to cure the problem until I switched the engine off and on.
    And if all that is true, I would have guessed the problem would be the pump or the actual haldex control unit - which I guess (again) is what tells the pump to come on/off
    ?
  21. Erf
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    Erf Member

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    [Jun 11, 2012]
    This is where I'm at. Been told by Audi specialist (4 rings) that my clutch plates are knackered, so I have bought a replacement rear diff (inc. haldex) and a pre charge pump just to be on the safe side. This is due to go on the car on Thursday (although I'm slightly nervous as the donor car is pre facelift, but with ESP and it's going on a post facelift S3)

    I've just plugged VCDS in to test the pump to see if there is any issue. When I followed the steps above, VCDS was saying pre charge pump is off. When I exited VCDS and tried again, it couldn't connect to the AWD controller! Slightly paniced by that.
  22. thegoal007
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    thegoal007 Another S3 owner....

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    [Jun 12, 2012]
    Did you go through and follow through the entire test , it puts the pump on/off enagages something or other off and on - did you go through all the test? Did you hear the pump make noises, provided you ran the test with only the ignition first time ? At the end of the test it will say END / Go back to start of previous menu - or something like that.

    If you could not complete the test because you lost communication or you couldn't even start it then you have a different problem.
    The only times where I've seen this happen it turned out to be an issue with dodgy electrical connections/earth strap.

    Oh , I should have also asked Erf, I presume removing the fuse or lifting the hand-brake one notch does not clear the problem ?
  23. Erf
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    Erf Member

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    [Jun 12, 2012]
    The thing is I didn't even know I have a problem! I've spun my wheels a couple of times which made me think either haldex is **** or not working properly. When I called 4 rings to have a look at my car for an overall inspection, Dean noticed that my rear wheels weren't spinning when the car was on axel stands and in first gear. He said from what he can determine, the haldex unit in knackered (the actual clutch) so it was not engaging. But I never experienced the dragging when cornering at slow speeds that you and SCLOUD have described
  24. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    [Jun 12, 2012]
    Good luck Erf. Do you have confidence in 4Rings' diagnosis? I don't know much about their quality of work but I know Awesome tried to quote me for a new rear diff and clutch pack despite me specifically asking for just the filter/oil/strap change, when they eventually did what I asked and it worked all they could do was say "oh well they could still be on their way out"....they then had the cheek to suggest it still might be a good idea to change the diff/clutch pack to a 2nd hand item, which for all I knew could be in a worse state!

    Hopefully they'll sort it for you, just don't let them walk you up the garden path!
  25. Erf
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    Erf Member

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    [Jun 12, 2012]
    I know there is an issue with my hladex as I have spun my wheels on dry roads. So I believe I have a different problem to others here as it looks like my clutch is disengaged where as everyone on this thread appears to have a clutch that is permanently engaged (which is why removing fuse 31 has worked).

    I just hope I don't have issues with the prefacelift rear diff!
  26. S3LOUD
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    S3LOUD Member

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    [Jun 17, 2012]
    Ohhh yeah the handbrake test. Tomorrow on the way to work i'll try lifting the handbrake one notch and see if this makes the dragging/banging go away like removing the fuse does. Errm i dont have VCDS but i do have access to a LAUNCH system and thats what i previously used to do the haldex test. Yeah when i did the test i do not remember hearing the pre charge pump at all. Could this be my issue???
    Also the controller pump and pre charge pump are two different things but what they both do is beyonddd me. This haldex system is one of the most consfusing things ive encountered when working on the car, just wish i could get the issue properly diagnosed and repaired because kinda at my wits end with it now lol.
    Does anyone know if replacing the pre charge pump can be done by myself or will it have to have the diff removed etc to replace it?
    Thanks again all! :D
  27. S3SYD
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    S3SYD Member

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    [Jun 18, 2012]
    I thinks it just 2 torx bolts and it pops out
    No U don't need to take the diff out it can be done on axle stands
  28. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    [Jun 18, 2012]
  29. melon454
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    melon454 New Member

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    [Jun 18, 2012]
    ive been having the same problem and after reading this tread i narrowed it down to an electrical fault then looked under car for earthing wire touched it and it came away in my hands. so thanks you lot for helping me and many others find the faults without getting your arse ripped out by a garrage
  30. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    [Jun 18, 2012]
    No problem. Nobody likes having their arse ripped out....well some people do, but we don't need to talk about that...
  31. S3LOUD
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    S3LOUD Member

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    [Jun 18, 2012]
    LOL^^
    Cheers for the link i think im gonna give it a go and try and clean out the motor myself and hope that it does the trick.
    As always will keep you all updated ;D
  32. Erf
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    Erf Member

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    [Jun 19, 2012]
    New rear diff and haldex pre charge pump going in today after a bit of a delay...let's see what happens!
  33. Erf
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    Erf Member

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    [Jun 21, 2012]
    Quick update - replacement rear diff went on minus the precharge pump (a bit of confusion with the guy I bought the diff from). I now have 4wd, BUT I now have the dragging issue that all on here have commented about. I took out fuse 31 and the dragging issue disappears. So I guess it's electrical and my guess it might have something to do with the earth strap as the rear diff I have has come from a pre facelift and my mechanic has cobbled together an earth strap to attach on. Will ask him to have another look when I get a chance.

    One more question, since taking out the fuse, the ESP light is on. Did this happen to any of you guys?
  34. thegoal007
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    thegoal007 Another S3 owner....

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    [Jun 24, 2012]
    I did the same thing over the weekend and took the fuse out and the problem did seem to go away. The esp light should and does come on. basically telling you it ain't working as you have removed the fuse !
    Anyway, I'm leaving mine minus the fuse for a few weeks as I'm sure I've tried this before and the problem was still there. The problem , for me , it was never consistent and although it tended to happen more frequently during winter than summer I am convinced (90%) it's an electrical problem too as I have mentioned previously running through the haldex tests in vcds when engine is running definitely cures the problem (with the fuse in!).
    Don't drive the car much except weekends, so we'll see how it goes.
  35. Erf
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    Erf Member

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    [Jun 24, 2012]
    I hope my problem isn't because I've put a pre facelift rear diff on my car...

    Will get my mechanic to have another look at the earth strap he managed to retro fit and just give the haldex ecu a clean. Hopefully that will sort things out.

    Cheers.
  36. S3LOUD
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    S3LOUD Member

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    [Jul 5, 2012]
    Still nothings changed with mine. Still driving without the fuse in and the dragging is still not there, however my ESP light doesnt stay on, only comes on when i press the ESP button.
    The only thing left to change for me now is the pre-charge pump. If this doesnt curee the issue then i have no idea what else it could now be.
    Thanks for the updates lads and Erf it'll be good to hear what conclusions come from yours when you get it back from the garage :)
  37. thegoal007
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    thegoal007 Another S3 owner....

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    [Jul 5, 2012]
    r u sure you said it correctly ?
    fuse is in and dragging is not there ?????????? you don't have a problem ?
  38. Erf
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    Erf Member

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    [Jul 5, 2012]
    'without the fuse in' ie fuse out! Strange your ESP light isn't on! Mechanic is picking up mine tomorrow!
  39. thegoal007
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    thegoal007 Another S3 owner....

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    [Jul 6, 2012]
    Sorry, for some blind moment I read that in a weird way.
    strange indeed the light does not come on. Mine doesn't come on straight away, but as soon as i drive off within a minute it does come on and stay on.

    removing the fuse is stopping the haldex controller & pump (?) from doing it's work so doesn't that indicate one of those 2 is faulty.........but the abs unit (at the other end of the car) also communicates with the controller so it could still be the ABS sending dodgy signals to the haldex controller!--- just to throw a spanner in the works!
  40. Erf
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    Erf Member

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    [Jul 6, 2012]
    That is an interesting theory as my VCDS scans showed an issue with my ABS sensor! Another one to add to the mix. Was hoping my car would be with my mechanic today, but postponed to Monday. The wait continues! Here's hoping its not expensive as I've just bought an RNS-E to retrofit...

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