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Thread: Level Control Bleeding/Charging

  1. #1
    Ross-Tech Employee DrPeter's Avatar
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    Level Control Bleeding/Charging

    Hello, from time to time we get asked, "How do we lower/raise or fill/drain the Air Suspension system?

    - This may be necessary if you are about to perform any Air Suspension system work and you want to drain the system of any dangerous air pressure.

    - It also is handy to know this procedure when filling the system, after a repair or to test for leaks.

    Please use this procedure with care, it should work on the Audi A8, Q7, A6 and the VW Touareg, Phaeton and the Bentley Continental.

    Hope this helps,

    drpeter


    Level Control Bleeding/Charging

    - Bleeding -

    Note: The bleeding procedure will lower the vehicle, proceed with caution and refer to the factory repair manual for proper repair information, warnings and cautions!

    If the Security Access code does not work, try Login or Coding-II

    [Select]
    [34-Level Control]

    [Security Access-16], [Login-11] or [Coding-II]
    [08367]

    [Basic Settings-04]
    Enter:
    Group 020 = to Bleed Pressure Accumulator
    Group 021 = to Bleed Front Axle
    Group 022 = to Bleed Rear Axle

    Field-4 will display the current pressure
    Note: System will time out after 60 seconds, the procedure maybe repeated as necessary to achieve the desired system pressure.

    - Charging -

    [Select]
    [34-Level Control]

    [Security Access-16], [Login-11] or [Coding-II]
    [08367]
    [Do it!]

    [Basic Settings-04]
    Enter:
    Group [023] = to Charge Pressure Accumulator
    Group [024] = to Charge Front Axle
    Group [025] = to Charge Rear Axle

    Field-[4] will display the current pressure
    Note: System will time out after 60 seconds, the procedure maybe repeated as necessary to achieve the desired system pressure.
    Last edited by Dana; 02-01-2017 at 09:58 AM.

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  3. #2
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by DrPeter View Post
    Please use this procedure with care, it should work on the Audi A8, Q7, A6 and the VW Touareg, Phaeton and the Bentley Continental.
    Only those models that do NOT use the UDS protocol for the suspension control module!

    -Uwe-

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  5. #3
    Verified VCDS User
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    I have tested this successfully on my car with no issues.



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  7. #4
    Ross-Tech Employee Jef's Avatar
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    Tacking this info onto this post:

    The problem:
    Identifying the source of a leak in an air ride suspension. Some times leaks can be hidden by a boot or plastic "cup" that is over the strut, thus one is not able to spray soapy water onto it. Other times, the valve block can have an internal leak. If no visual location of the leak is found, how does one know where the failure is and what items to replace.

    My theory:
    If there is a way to isolate sections of the air ride suspension, then one could determine if the leak is before or after X location. Since the hoses for the air ride are hard plastic, you can not pinch them off like a vacuum line. There needs to be some way to put a manually operated valves in the line.

    To that end, I submit this for peer review:



    The MV309-4M is an inline ball valve. I paid $17.12 plus tax.
    The 32PLP-4M is a repair piece to join 2 pieces of the hose together. I paid $2.43 plus tax.
    The blue tubing is from a wrecked A6 Allroad a customer sent to me. Thanks Joe.

    The plastic tubing is very easy to cut and then just pushes into the fittings. One would cut the tubing close to the air ride suspension valve body, or close to the strut and the fit the ball valve in place. Air up the suspension and then close off the ball valve.

    • If the strut is the source of the leak, then it will bleed down and the car will sag.
    • If the leak is with the valve block, then with the ball valve being closed, the strut can not loose air back through the valve, thus the car stays aired up.


    The ball valve is removed and the cut line can be repaired with the 32PLP-4M piece, at less than $3 a pop, a shop could keep several on hand. I am told these pieces are rated to 300PSI.

    One will need to take precautions when cutting the lines. The vehicle will need to be supported on a lift (or jack stands) so that the wheels are still touching the ground and then use VCDS to bleed the air out prior to cutting.

    I've not tested this method of suspension leak isolation. Feedback welcome.
    Jef
    Ross Tech Support Team, Alpha Squad
    Auto-Scan, learn it, love it, live it... then check the fuses.

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  9. #5
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    Hi there,

    I hope this question fits in here. If not, please feel free to delete, move or what ever it is you would like to do :-).

    I have an Audi A6 4f Allroad (2010) and the distances on a level surface were off a bit so I first tried to calibrate it. That didn't quiet work as the car indeed moved up a bit in the world but it had the same differences as before. Now I read on another forum that bleeding all 4 air pockets and refilling them would give the system kin-doff a "reset"... Well I tried that and calibrated twice afterwards and It looks quiet a bit better now.

    Anyway, I still got a question in regards to the VCDS measuring blocks. I attached a screenshot from the other day when the car was in the garage (Level) and had stood there for a while (4 - 5 hrs).

    In group 004 it shows a distance which I guess is how far the AAS thinks it is off the actual value measured on the wheel. Now, would I add or subtract that "distance" value to the "content" value? Or don't I do anything at all with them? The measured value on the tire is as follows:

    LHF: 382.2mm
    RHF: 382.2mm
    LHR: 371,7mm
    RHR: 378.7mm



    As you see, what AAS has as current value is already what's on the tyre. (I use two square edge tools with spirit level so I can measure very accurate down to the mm while the after "." is guessed by how far it went over... a bit like a massive veneer callipers but not quiet as accurate). Now what do the distances tell me? If I were to add them it would make sense as it would be really close to the spec 388mm (front) and 380mm (back). However, these little buggers of numbers have a big fat "-" in front. So if I were to subtract, it would be wrong ... .

    I might just have a thinking error in this and might also get wound up a bit to much over it . I don't know.

    A little advice would be fantastic if possible .

    Cheers

  10. #6
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by A6Aussie View Post
    Now, would I add or subtract that "distance" value to the "content" value? Or don't I do anything at all with them?
    You should always put in the actual measurements. When you are in adjustment mode, the car thinks it has adjusted itself to the "nominal" measurements already and will calculate offsets based on the 'actual' measurements you enter.

    The one exception is of if you would like to to change the car's ride height; in that case you would "lie"; for example if you put in the actual measurement plus 10mm, then the car would think it is 10mm too high and should end up 10mm lower. But there are limits to what can be accomplished with this technique.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  11. #7
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    Hi Uwe,

    thanks for your reply.

    That's what I did. I always put the actual measurements in. The result is the above. I do the whole procedure with running engine, nobody in the car and the car empty via open window.

    I noticed however, if I push the car down (sitting ing it) it goes into minus... so that would mean that I have to add the "Distance" value to the "Content" value, mathematically ignoring the minus, in order to get the actual hight the AAS thinks it is in.

    Here is what I mean:

    005: 382.2 382.2 371.7 373.8
    + (or - as - - = +) + (or - as - - = +) + (or - as - - = +) + (or - as - - = +)
    004: -4 -4 -7 -5
    Added: 386.2 386.2 378.7 378.8

    However, I would still be baffled as to why it doesn't go up to the 388 and 380 as suggested on the Ross-tech instruction page...

    Cheers
    Last edited by A6Aussie; 05-21-2018 at 11:22 PM.

  12. #8
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    Anybody an idea?

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