# Air Suspension Problem on the Phaeton



## SoftballBud31 (Apr 26, 2006)

Have a Phaeton with an air suspension problem, and I am wondering if anyone else has had a problem, and if so what was the fix? 
Air pump was replaced already. Thanks for any input.


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## culverwood (May 20, 2005)

Check for rodent damage to air pipes, that was my problem.


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## W126C (Jan 27, 2005)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*

Hi Bud,
I have not had a problem with my Phaeton suspension, but did have with my T-reg. The tech rebuilt the air compressor. Something about the rings? Good luck.
Regards,
Brent


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## PanEuropean (Nov 3, 2001)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*

Hi Bud:
What exactly are the symptoms of the 'air suspension problem'?
I think you probably know this already from following other posts in the forum, however: If the vehicle power supply battery (the left battery) voltage drops below nominal, one of the very first indications that the owner will get will be a 'Suspension Fault - Workshop' message in the Y24 display. The message is spurious - in such a case, there is nothing at all wrong with the air suspension system - the problem is that the J197 Suspension Controller (controller 34) is quite sensitive to low voltage conditions, and will generate a fault message if the power supply to that controller starts to drop, as is the case with a slightly discharged vehicle power supply battery. The suspension controller is the 'Canary in the Coal Mine' for low battery voltage.
My troubleshooting suggestion to you would be this: Unless the vehicle obviously has suspension problems (like, it arrives at the dealership dragging its ass on the ground), focus your troubleshooting efforts on the vehicle power supply battery, and on the J367 battery management controller (controller 71). In particular, check the part number suffix of the battery management controller. If it is A or B, replace the thing with a new controller that has a C suffix and software revision 2700 in it. Note that you cannot flash-update the software, there is actually a small hardware difference between the B and C version controllers.
If you think that the suspension fault messages might be spurious, have a look at this post: J367 Battery Monitoring Controller Replacement. Two other suggestions as well:
*1)* Talk to the owner and find out if he or she ever sits in the car with the ignition on, but the engine off. Doing this for more than about 5 minutes can deplete the left hand battery enough for the suspension controller to start throwing codes. The easy fix: Start the engine if the ignition is to be on for more than 5 minutes.
*2)* Talk with the techs and make sure that they are hooking up a Midtronics charger directly to the terminals of the left battery whenever the subject Phaeton is in the shop. Hooking the battery maintainer up to the terminals under the hood won't do any good at all - those terminals don't connect to the battery, they are there for jump-starting only. See this post for more detail: NAPA Battery Maintainer for a Phaeton (Includes TB 00-03-11). There is a TB attached to that post that provides a troubleshooting flowchart if the car comes in with a low voltage condition on the vehicle power supply battery.
Lastly, there is a way to check and see if the owner has been discharging the vehicle power supply battery, it works like this: 
Open up controller 09 (central electrical) with a 5052, and go to adaptation channel 01. Read the value that is present in that channel - it will be between 0 and 14. That number tells you how aggressively the central electrical controller has had to intervene and shut down services as a result of voltage drops. (For more background information about the 'Intervention Load Management' function on the Phaeton, see this post: Intervention Load Management on the Phaeton)
Anyway, take note of what the reading is (likely between 12 and 14), and write it down. Now, enter a new value of 00 into adaptation channel 01 and save that. This will reset the meter to 0. Have the owner drive the car until the problem appears again, then, read the value in that channel again. If it is between 0 and 12 - that seems to be the normal range. But, if it is 13 or 14, the battery is getting seriously discharged, and the car is probably generating 'Suspension fault - workshop' messages as a result of that low voltage condition.
To summarize:
*1)* Check left battery voltage with the Midtronics tester.
*2)* Check colour code of controller 71 and make sure it is C or higher.
*3)* Interview the owner and techs and make sure they are not inadvertently running the battery down. You can double-check on this by looking at the intervention load history record as described above.
Michael


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## SoftballBud31 (Apr 26, 2006)

*Re: Air Suspension Problem on the Phaeton (PanEuropean)*

Michael, it came in dragging ass. We are still diaging the car, but think it could possibly be a failed relay (based on what techline has told us) or what VW simply calls a valve unit. We know it is not the pump. Do you have any other suggestions? Tech has ruled out the battery portion of the equation.

_Modified by SoftballBud31 at 6:41 AM 7-28-2006_


_Modified by SoftballBud31 at 6:42 AM 7-28-2006_


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## SoftballBud31 (Apr 26, 2006)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*

Latest update on the air suspension problam. After numerous tests that were sugeested by VW, my Tech created his on test to determine the problem. It appears that 3 of the 4 levelling sensors have failed. We should know the answer later today.


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## chrisj428 (Feb 26, 2005)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*


_Quote, originally posted by *SoftballBud31* »_It appears that 3 of the 4 levelling sensors have failed. We should know the answer later today.

I'm going to ask what may be perceived as a dumb question: are the sensors installed the right way?
The only sensor failure I've seen is the occasion where the sensor was installed backwards. They will fit either way. I believe the correct way is < towards the outside of the vehicle as opposed to > towards the inside of the vehicle. 
Repositionong the sensor correctly solved the problem.


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## SoftballBud31 (Apr 26, 2006)

*Re: Air Suspension Problem on the Phaeton (chrisj428)*

Chris,
Not sure about that. But, the car has 13,000 miles and now the problem developed. If they were installed incorrectly, I would think the problem would have existed from the beginning.


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## SoftballBud31 (Apr 26, 2006)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*

Chris, Michael...anyone else who knows the Phaeton. Still working with the air suspension problem. Everything leads to an air leak, but we can not find one. If it were a slow leak, it would leak down overnight, and a pinhole night do that. But, this seems to leak down very quickly. It seems as if that would be very noticable.
Any best guesses? We are working with techline as well, but it seems like we have hit a wall.


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## PanEuropean (Nov 3, 2001)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*

I'm not familiar with the plumbing of the air suspension system, however, if a leak is affecting more than one wheel, I would concentrate my efforts on looking for leaks in the air compressor area (middle of the spare tire). I think you could use the same soap solution used for searching for AC leaks.
Michael


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## chrisj428 (Feb 26, 2005)

*Re: Air Suspension Problem on the Phaeton (SoftballBud31)*

I would put the vehicle up in the air, allow the wheels to hang down via their own weight and soap the very tops of the air bags, looking for a pinhole leak.
I have seen only one bag leaking. It was on a Touareg which would genuflect every night. We finally found a pinhole leak at the top of the passenger front strut. Strut replaced, problem solved.


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## GripperDon (May 9, 2005)

Rember the very old Beetle ad "VW construction keeps out dampness" showing a bettle floating in the water from below. Maybe that would locate the leak.


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## W126C (Jan 27, 2005)

*Re: Air Suspension Problem on the Phaeton (chrisj428)*

Chris,
Is there a specific fault code for the compressor verses air bags? Or is it just a suspension code? What is the leak down test in this case?
Regards,
Brent


_Modified by W126C at 8:13 PM 8-3-2006_


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## chrisj428 (Feb 26, 2005)

*Re: Air Suspension Problem on the Phaeton (W126C)*

Brent,
Not that I've seen. I have seen faults stored for the level senders, but not for leaks per se.
Any leak-down tests would be strictly mechanical in nature, i.e.: watch & wait. Small leaks are, obviously, very difficult to locate...however with enough soapy water and due diligence, they can ultimately be found. (It took us three days to find the one in the Touareg, it was that minor!)


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