2012 A8 4H 34 level control coding

   #41  

Uwe

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All doors closed? Does the module see them as all closed?

Look in Measuring Values and see if any of the sensors is grossly out of whack with the others.

-Uwe-
 
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AvernturaA8

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Hi Uwe, thanks for the reply. Yes, all doors are closed, front windows open during the procedure. Fuel tank around 3/4 full.

One note is that I am not using a battery tender during the procedure.

Observed Symptoms:
My left front wheel is evidently low, my right front is evidently high.
Ther rear wheels are not as bad, with the left lower than right as well.


Here are some sensor readings that may be of interest. I can extract more.

Code:
Sunday,27,September,2020,02:21:40:56142
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 20.4.2.0 (x64)  HEX-V2 CB: 0.4513.4
Data version: 20200730 DS317.0
www.Ross-Tech.com




                Address 34: Level Control  (4H0 907 553 C)

02:21:31
  IDE02942   Value of PWM signal left front vehicle height 38.21 %
  IDE02943   Value of PWM signal right front vehicle height 46.71 %
  IDE02944   Value of PWM signal left rear vehicle height 40.88 %
  IDE02945   Value of PWM signal right rear vehicle height 39.19 %
  IDE03057   Value of PWM signal left front shock absorber 50.00 %
  IDE03059   Value of PWM signal right front shock absorber 50.00 %
  IDE03061   Value of PWM signal left rear shock absorber 50.00 %
  IDE03063   Value of PWM signal right rear shock absorber 50.00 %
  IDE03123   Last measured pressure in left front pneumatic spring bellows 7.4 bar
  IDE03124   Last measured pressure in right front pneumatic spring bellows 7.4 bar
  IDE03125   Last measured pressure in left rear pneumatic spring bellows 4.6 bar
  IDE03126   Last measured pressure in right rear pneumatic spring bellows 4.6 bar
 
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   #43  

Uwe

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I don't see anything obviously wrong there. :confused:

-Uwe-
 
   #44  

AvernturaA8

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Hi wanted to add some observations. I vented both axles in order to drop the car to its lowest level to observe the PMW signal from the level sensors. Here are the measured values:

Code:
  IDE02942   Value of PWM signal left front vehicle height 27.47 %
  IDE02943   Value of PWM signal right front vehicle height 73.48 %
  IDE02944   Value of PWM signal left rear vehicle height 22.81 %
  IDE02945   Value of PWM signal right rear vehicle height 67.70 %
Is it normal for the left side and right side sensors to read values inverted? That is left-side sensors decrease in value as the car drops, while right-side sensors increase in value. Is this normal behaviour?
 
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   #45  

Uwe

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Is it normal for the left side and right side sensors to read values inverted? That is left-side sensors decrease in value as the car drops, while right-side sensors increase in value. Is this normal behaviour?
I wouldn't think so, but I don't have access to a car with a suspension like that to confirm.

-Uwe-
 
   #46  

AvernturaA8

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Hi, I wanted to provide an update and my ride height situation

After many attempts to calibrate the vehicle and always getting stuck at "aborted - safety reasons" I took the vehicle to and Audi/Volkswagen certified shop. After a few hours of diagnosing the car the technician was unable to get past the same error I was having and was unable to provide a solution.

But I do have a positive update to share. Today, I decided to try an option on VCDS that I had never dared to try before. "Startup to Normal Level and Permanently Deactivate Level Control". Selected this from the dropdown, pressed "OK" and after like 30 seconds the function completed.

The result, the car is now leveled! The fault on the dash remains but at least the car is sitting at the same height between left and right.

Here are the readings from VCDS with this improved posture:
Code:
Address 34: Level Control  (4H0 907 553 C)

18:28:26
  IDE02942   Value of PWM signal left front vehicle height 36.50 %
  IDE02943   Value of PWM signal right front vehicle height 58.61 %
  IDE02944   Value of PWM signal left rear vehicle height 44.33 %
  IDE02945   Value of PWM signal right rear vehicle height 48.51 %
  IDE03123   Last measured pressure in left front pneumatic spring bellows 12.0 bar
  IDE03124   Last measured pressure in right front pneumatic spring bellows 6.6 bar
  IDE03125   Last measured pressure in left rear pneumatic spring bellows 7.5 bar
  IDE03126   Last measured pressure in right rear pneumatic spring bellows 3.1 bar
Note how the pressures readings are much higher on the left than on the right, and yet the car is leveled.
 
   #47  

Uwe

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I took the vehicle to and Audi/Volkswagen certified shop. After a few hours of diagnosing the car the technician was unable to get past the same error I was having and was unable to provide a solution.
An independent shop? Or a dealer?
Here are the readings from VCDS with this improved posture:
The dramatic (~2:1) pressure difference between left and right bothers me. Why would so much difference be needed when the vehicle is level?

-Uwe-
 
   #48  

AvernturaA8

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An independent shop? Or a dealer?
It was an independent shop.

The dramatic (~2:1) pressure difference between left and right bothers me. Why would so much difference be needed when the vehicle is level?
-Uwe-
Yes, the pressure difference level sure surprised me too. It would be nice to have some reference values out of a healthy A8 as it may provide clues of what's happening. I also have not been able to confirm if the inverted behavior of the PWM values between the left and right sides is normal.

And unfortunately, after a few minutes of driving it later in the afternoon, the car reverted back to its bad posture, with the right side (front) being almost two inches higher than the left.:(

My current heights as measured from the floor to the fender are LF: 28.25", RF: 29.5", RL: 29.75" RR: 31.25"
 
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