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Allroad Suspension Stuck on Level 4 (L4)

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by Mudplugger, Dec 27, 2010.

  1. Mudplugger
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    Mudplugger Member

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    I've been leaving my Allroad parked on Level 3 (L3) for the last few days as the extra clearance has been useful around town, and it has happily dropped to Level 2 (L2) at the first sign of a fast road. As intented by Audi, so all good.

    Yesterday morning however it refused to drop down to L2 on the motorway, and insisted on covering 50 miles on L3. I stopped a couple of times during that, turned the ignition off, waited a few seconds, and turned it back on again. This did no good and I reached my destination stuck on L3.

    But worse was to come.

    Yesterday evening the car decided, at about 70mph, to jack itself up from L3 onto L4. I did the normal things of pulling over, turning off the ignition etc. None did any good (except parking on a steep sideways slope which momentarily showed L3 and then went straight back up to L4) and I completed my motorway journey, at motorway speeds, stuck on L4. Occasionally on the motorway the L3 & L4 LEDs flashed together, 4 times, presumably to show that they knew where the suspension should be, and then went out again as the car couldn't get it down there.

    The warning light on the revcounter, with the up & down arrows, illuminated dimly but constantly.

    There is now basically no give in the suspension and the car is very bouncy to drive. It's exactly what I don't want on a slippery surface!

    So today I have used VCDS to log all fault codes present, just in case, and then clear them.

    Then I fired the engine up and tried, once again, to lower the suspension from L4 down to L3 by pressing the down button; I did this in my drive, without moving the car. After blinking the L4 LED 64 times (I think) the car stopped trying. Pressing the down button again did nothing, so the system had clearly given up trying.

    I turned the ignition off, tried again, failed again (still without moving the car), and then used VCDS to extract the fault vodes. Here's what it said:

    -------------------------------------------------------------------------------
    Address 34: Level Control Labels: 4Z7-907-553.lbl
    Part No: 4Z7 907 553 F
    Component: - 2C1A1 D060
    Coding: 25500
    Shop #: WSC 00539
    VCID: 4895ABBB42C1

    1 Fault Found:
    01400 - Suspension Level Control
    08-10 - Control Limit Surpassed - Intermittent

    -------------------------------------------------------------------------------

    So, frankly, I'm at a bit of a loss here!

    Recent problems with my compressor (see http://www.audi-sport.net/vb/a6-s6-...108538-a6-allroad-suspension-frozen-cold.html ) would lead me to suspect it's at fault. But surely that would stop the car going up (as it did before I added the tool oil) not down?

    I don't believe the fault lies with the level sensors (even though one was featured in the list of faults I cleared with VCDS before repeating the problem) because they knew I should be at L2 on the motorway, but wasn't, and none are shown in the VCDS fault log now.

    I'm wondering if there is a relay or similar that controls the dump valves that could be at fault, and refusing to open thyem to let the car down? Or some water somehow frozen in there? But even that doesn't explain what made the car decide to jack itself UP from L3 to L4, when it should really have been trying to lower itself DOWN from L3 to L2.

    So I'm stumped.

    Any ideas anyone?
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  2. Mudplugger
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    Mudplugger Member

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    It's a bit warmer today, +5C, so if anything was frozen it should have melted by now. However, my car still didn't get the "go down" hint when I instructed it to; so I decided to encourage it a bit with some hot air underneath, just to be really sure that nothing was still frozen (despite the thermometer we still have lots of snow on the ground):

    I put the car up on ramps, got my hot-air paint-stripper, and crawled underneath. I wafted the hot air around, in my best approximation of a fan heater trying to distribute heat. Suddenly there was a 'pop' then a loud 'hiss', and the rear suspension (i.e. where I was lying) started to descend! I exited from underneath, fast.

    Unfortunately it only came down on one corner (left rear) and subsequent investigation revealed that I have now blown a hole in the black tube that links the NSR airspring to the control block. So now I need a new tube, or it's like driving around with a blown airspring (only worse because the other 3 corners are still stuck up on L4...), and the main-dealer parts department doesn't open until 08:30 tomorrow.

    Meanwhile, apart from having concluded that the valve block near the compressor, into which six coloured tubes fit, is sealed tight I'm no nearer to solving my problem. I don't know if it's sealed firmly because of a fault with it, or whether it would work perfectly if it simply received the signal to do so. Furthermore, I have absolutely no idea how to test this, other than replace the part with one that is known good and see what happens (all VCDS can tell me is above).

    I suspect that the valve block is fine however, because even if it was frozen solid that wouldn't explain why the car decided to jack itself up to L4 at 70mph. So I need to look elsewhere.

    So where's the 'brain' module that sends the signals to control all this, because that's most likely where the problem really lies. Does anybody know?
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  3. Mudplugger
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    Mudplugger Member

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    I've just ordered new pipe and union which will be with main-dealer parts department tomorrow morning, cost £50.

    If nobody has any ideas about how to get the car off L4 (and I'm all-out given that it jacked itself up there in the first place) I shall probably leave it with the main-dealer and let them sort it out for me.
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  4. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    OUCH, sounds expensive to fix.

    I wonder if the valve block has siezed, it sounds like the command is getting to the susp ECU but the suspension is filing to comply.
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  5. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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  6. Mudplugger
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    Mudplugger Member

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    Mark, thanks very much for your help.

    I'd already found the first and third links you suggested, but not the second ( AudiForums.com - View Single Post - HELP with front air ride height sensor issue ), so thanks again. I hadn't realised that the left level sensors are connected to headlight ECU #55. That said, I probably should have as when the front left sensor played up before I got the warning light to say that the Xenon mains couldn't self-level. However, VCDS is currently showing no faults on #55.

    My system is thoroughly confused now though because with an air-pipe blown it changes its mind as to whether its on L1 or L3 (though 3 corners are jammed on L4!) depending upon what I do with my trolley jack under the sill on that corner. I was watching the measuring blocks (ECU #34, nos 4, 5 & 6) and graphing on VCDS earlier, and all appear to return sensible readings as I cause that wheel to move up and down with a lack of air pressure.

    I'll get the new airpipe tomorrow (just moved 2 tons of building materials so I can use motorhome to go collect it...) and then at least I should get it all stuck up on L4 again, so more driveable than now!

    Meanwhile, VCDS appears unable to either level the car, or drop the suspension on any corner, which again suggests a problem with one of:

    • control block
    • Venting Solenoid for Level Control (N111)
    • wiring

    However, I'm guessing it's not the middle of those 3 as I don't have "01397 - Venting Solenoid for Level Control (N111)" reported. That just leaves the control block itself, or the wiring...

    Or of course the #34 Level Control ECU as that would also explain why the car decided to raise itself (nothing I did...) to L4 while travelling at 70mph.

    Do you know where this ECU is located as I'd like to check it for damp etc as a starting point.

    Meanwhile, in case I can't fix it, the car is booked into an Audi main-dealer for Wednesday 5th January. However, at £120/hour for labour + Audi parts prices I propose to keep going on it myself for as long as I can!

    Thanks,

    Andrew
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  7. murran
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    murran Active Member

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    im presuming it maybe some sort of phsical fault with a valve being unable to exhaust air to lower the car. air line oil fooking it up?

    but why it would go up to level 4 at 70 mph? i dunno. should be on level two at that speed i think, even if you started your journey on level 4.

    an expencive trip to audi then?
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  8. Mudplugger
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    Mudplugger Member

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    This is my assumption as well. The air is certainly sealed in there OK, no problem in that respect, it just can't get out again. Whether that's because of a relay/solenoid failure, or because it's not getting a signal in the first place (perhaps ECU problem or broken wire), is another matter entirely.

    I'm always a fan of suspecting the last thing that changed as being the likely cause for failure, and then reversing it to see if that fixes the problem. In this case we have:

    • Unusual levels of cold and corrosive road salt (my current commute is 200 miles/day)
    • Too much oil in compressor

    Unfortunately, neither are something I can reverse for testing!

    What I'm hoping now is that following the oil advice hasn't damaged the insides of my airsprings too!


    I replaced the airpipe yesterday (most expensive piece of nylon tube I have ever bought - what a rip-off) and, when I started the engine and pressed the 'up' button, the 'car' politely jacked itself up to L1 as commanded. It sat there until I pressed the 'up' button again before politely going up to L2.

    Of course when I say 'car' what I really mean is 'NSR corner of car' as everything else stayed firmly stuck where it was. Nothing came down.

    I decided to stop at L2 and see what happened. I then went out for a 50 mile drive (I needed to go there anyway), 40 of it on motorways.

    Considering that both front corners are sat on L4, the NSR (with new pipe) is sat on L2, and the OSR looks to be on L3 ... the car handled quite well. Also, despite stopping and restarting a couple of times, the NSR hasn't felt the urge to jack itself up to L4 to match the rest (but neither have they come down to match it and the level light on the dash shows L2...).


    Quite possibly :(

    However, if they identify a need for a new compressor I'll probably save myself £500+VAT on parts, plus labour, and get this one off eBay:

    compressor air suspension audi A6 allroad 4Z7 616 007 A on eBay (end time 08-Jan-11 15:14:30 GMT)

    I'm still sore about being charged £35 for a roughly metre length of tube, when I could probably buy a 30m roll of it for less than a tenner :mad:
    #8
  9. murran
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    murran Active Member

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    why not undo the other 3 pipes to the other suspension units to drop it down? see what it does?
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  10. Mudplugger
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    Mudplugger Member

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    I did consider this, especially as it wouldn't take long to do, but I'm conscious that the air in the system is under a huge amount of pressure (10-15 bar) and I'm wary of damaging the connector threads (brass connector screws into (what looks like) nylon airspring seat) when they get to the last thread or so while doing this.

    The last one only came down because the pipe burst while I was working under the car, and it was obvious from the noise and the way the tube wall ruptured that the pressure was substantial.
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  11. murran
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    murran Active Member

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    theres actually more like 3-6 bar in them.....
    if you just slacken them off a turn the air will hiss out slowly.
    #11
    Colin Allroad TDi likes this.
  12. Mudplugger
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    Mudplugger Member

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    OK, I'll give it a shot.

    Would you advise slackening off at the airspring end, or on the block under the rear of the car?

    If the latter, do you know why it has six nylon tubes to control the four airsprings?
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  13. murran
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    murran Active Member

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    id recommend at the valve..... theres six pipes cus one of the black ones is the feed from the pump. the other black one (i "think" its black and not one of the coloured ones.......) goes to a pressure reservoir tank in the n/s/r wheel arch. and 4 coloured ones for each air bag.
    Last edited: Jan 2, 2011
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  14. Mudplugger
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    OK, having been under and done as advised, of the six pipes:

    • Red & Green go to the front suspension (left & right)
    • Black & Blue go to the rear suspension (left & right)
    • Brown & Purple go elsewhere (I think compressor & reservoir respectively)

    That's on my (2003/53) car anyway

    I've let the air out and lowered all 4 corners, that was easy. It took about 10 flats (i.e. less than 2 turns) on each connector, and the car was sitting on the bumpstops. It's no longer stuck on L4. But...

    When I switched the ignition on the car very slowly raised itself on OSR, then OSF, but still sits pretty much on the ground on both NS corners. The warning LEDs now show that the car is unable to reach even L1 all round, although a visual inspection suggests that it's around L1-L2 on the right, but collapsed on the left.

    I took it out for a 5 mile test drive, with VCDS plugged in and measuring blocks 4, 5 & 6 on module #34. The compressor gets slightly over 100C before cutting out, and air pressure gets past 16 bar, both of which imply that (despite being extremely wek & slow) the compressor is working.

    The suspension height/extension readings give the impression that while NSF is compressed, OSR is extended to compensate. This doesn't explain why NSR now can't lift up, even though it was happy to do so when the rest of the suspension was stuck on L4 and I replaced its airpipe a few days ago.

    So albeit the compressor is perhaps somewhat past its prime, is it really the problem??? Is the real problem somewhere with the sensors and/or control logic???

    As a thought, I'll try putting a jack under the left side sill tomorrow, to take some of the weight off it, and see if the compressor can then cope with putting air into those springs and holding it there.

    I'm guessing that you'll advise me to buy a new compressor anyway, even if only because it's hard to diagnose any other fault with it behaving so badly, but I am certainly wondering if it was originally the real culprit.

    I am now thinking that is was my addition of air-tool oil that's killed the system, quite possibly something other than the compressor.

    Anyway, viable replacement compressors would seem to be:


    I'm not convinced that Arnott will actually work out cheaper than the German/eBay alternative, after I've paid for 20% VAT and ??% customs duty.

    But (before I blow £400) do I really need a new compressor?
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  15. murran
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    murran Active Member

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    in your position...... a new compressor is where id start.

    seems odd that now it wont pump up different corners of the car. air tool oil buggered up the valve block?
    #15
  16. Mudplugger
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    Mudplugger Member

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    I'd agree except that when I pulled the pipe off earlier and held my finger over the end of pipe, the compressor seemed to have reasonable suction. It's slow, sure, but it's not completely useless. As to where the air's going is another matter.

    I have to say that this is the conclusion I have come to as well.

    My plan for tomorrow is to pull the red (i.e. front left) pipe off the bottom of the block, switch the ignition on, and see if any air actually comes out of the port. If it does, I'll reconnect that end of the pipe and then disconnect at the airspring to see if the air makes it that far.

    At least this way I should learn where the problem lies, and currently I'm suspecting the valve block. Specifically, my guess is that the oil has caused a seal to fail in the block and/or broken down a piece of rubber elsewhere, and that a tiny piece of debris is stuck somewhere in the block stopping a valve inside it from closing fully.

    I'm hoping that a block is cheaper than a compressor and/or readily available on eBay...
    Last edited: Jan 3, 2011
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  17. binojkmathew
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    binojkmathew New Member

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    Hi Mudplugger,

    Did you sort your problem yet?
    I got an 02 Allroad for more than a year with similar problem like your. NSF and NSR suspension are lower than the OSF OSR.
    I changed the compressor with a used one to no use, but it worked faster than my tired old pump.
    What I suspect is the valve block, which might need a good clean and lubrication.
    Can you please update on your suspension?

    Matt
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  18. murran
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    murran Active Member

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    does the suspension go up and down ok? no warning light on?

    you say its lower on one side than the other? is this the case while the engines running? or is it when the cars been parked up (say over night) it sinks to one side? does it correct itself when you start up?

    if the cars parked up with the engine running say on l3... does the suspension pump keep cutting in every few minutes?
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  19. binojkmathew
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    binojkmathew New Member

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    Sorry Murran for taking long to respond, I thought there will be some updates coming to my email.

    it lower on the near side always, front and back near side.

    there is no over night sinking,

    latest update is that I tried to do the vag-com adaptation and guess what unsuccessfull now in completing the procedure coz of the level not reaching/ learnerd by the nearside front suspension. However I can manually raise and lower, but the suspension light is ON all time as I did not complete and save my adaptation.

    This weekend I many try squirting some air tool lubricant to the air inlet at the spare wheel area.

    and to your last question, I can hear compressor/valve dumping air now and then, so some time when parked trying to raise and then lowering a bit itself.

    thanks for your response and appreciate your take on this.

    Mathew

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  20. murran
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    murran Active Member

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    i wouldnt do the airline oil thing, it doesnt do the valve block any good.
    can you read the actual values for the ride height sensors? do they all change when you manually raise/lower the car? are the values for the n/s approximatly the same as the o/s? are all the sensors and little rods secure?
    #20

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