Vw phaeton air suuspension issue

[1611AZTEC]

Hi all I'm trying to help out my elderly brother who owns the 2007 Phaeton V6 Diesel 130k miles with collapsed front suspension and I really don't want him to have to give it away for scrap value..
I'm a retired engineer and vehicle technician with some previous diagnostic experience but a little old to get my head around some of the more complex modern vehicle issues so would really appreciate any pointers or advice.

Front suspension went down overnight and fails to rise at all with " vehicle low etc " warning on dash. Jack mode does not select either so suspect an air bag has let go.

The rear appears to be at normal height. The engine starts and runs fine with no hesitation.
The suspension compressor under the boot floor doesn.t run or make air so I cannot check for a leak.
I have checked the compressor main 60 amp fuse and also the 5amp fuse 19 for the suspension control module - both are good
I have also checked the compressor relay which checks out as good on the bench.
I have bridged the relay power socket terminals and can hear the compressor running under the boot floor its quiet and confirms that its functional.

On the relay panel I have checked for power "to the relay" and there is none, engine running or not running.

Today I managed to borrow an impressive Topdon 800 Diagnostic interface and pulled a number of codes as below but cannot put my finger on why there is no power to the relay and in turn the compressor.



For some unknown reason I cannot upload any images or a PDF of the scans so here's a brief description of the codes etc.

Fault codes stored indicate a leak detected and a list of others that I need to decipher to see if I can trace the reason for no compressor..
Initial level control fault codes were

01583 leak detected in system -

01399 self levelling compressor relay -

01598 drive battery voltage .

The 01399 relay - This relay has been checked and tested on the bench and is good but on checking the socket terminals terminals with a meter there is no switching power to energise the relay so compressor doesn't run.
Leak detected code, was expected as this is either a cause or symptom of the issue.
The drive battery voltage code 01598 would not clear the other two did initially. In the list there is also Parallel battery connection relay codes - open circuit code 00086.

Data streams suggest J403 COMP relay "OFF" as expected.
Supply voltage terminal 30 14.4 volts. and terminal 15 13.7 volts.
Reservoir tank pressure G291 5.86bar

Desperately trying to pinpoint the reason why no power to compressor or relay so I can run and test for leaks..

Thanks in anticipation though realise I may well be on a fruitless path but worth a shot here.as I know from previous VW issues there are a number of very clued up members on here.. -

Any pointers very much appreciated.

[Crasher]

What is the VIN?

[1611AZTEC]

Hi all I'm trying to help out my elderly brother who owns the 2007 Phaeton V6 Diesel 130k miles with collapsed front suspension and I really don't want him to have to give it away for scrap value..
I'm a retired engineer and vehicle technician with some previous diagnostic experience but a little old to get my head around some of the more complex modern vehicle issues so would really appreciate any pointers or advice.

Front suspension went down overnight and fails to rise at all with " vehicle low etc " warning on dash. Jack mode does not select either so suspect an air bag has let go.

The rear appears to be at normal height. The engine starts and runs fine with no hesitation.
The suspension compressor under the boot floor doesn.t run or make air so I cannot check for a leak.
I have checked the compressor main 60 amp fuse and also the 5amp fuse 19 for the suspension control module - both are good
I have also checked the compressor relay which checks out as good on the bench.
I have bridged the relay power socket terminals and can hear the compressor running under the boot floor its quiet and confirms that its functional.

On the relay panel I have checked for power "to the relay" and there is none, engine running or not running.

Today I managed to borrow an impressive Topdon 800 Diagnostic interface and pulled a number of codes as below but cannot put my finger on why there is no power to the relay and in turn the compressor.



For some unknown reason I cannot upload any images or a PDF of the scans so here's a brief description of the codes etc.

Fault codes stored indicate a leak detected and a list of others that I need to decipher to see if I can trace the reason for no compressor..
Initial level control fault codes were

01583 leak detected in system -

01399 self levelling compressor relay -

01598 drive battery voltage .

The 01399 relay - This relay has been checked and tested on the bench and is good but on checking the socket terminals terminals with a meter there is no switching power to energise the relay so compressor doesn't run.
Leak detected code, was expected as this is either a cause or symptom of the issue.
The drive battery voltage code 01598 would not clear the other two did initially. In the list there is also Parallel battery connection relay codes - open circuit code 00086.

Data streams suggest J403 COMP relay "OFF" as expected.
Supply voltage terminal 30 14.4 volts. and terminal 15 13.7 volts.
Reservoir tank pressure G291 5.86bar

Desperately trying to pinpoint the reason why no power to compressor or relay so I can run and test for leaks..

Thanks in anticipation though realise I may well be on a fruitless path but worth a shot here.as I know from previous VW issues there are a number of very clued up members on here.. -

Any pointers very much appreciated.

Hi Crasher thank you for your response. VIN is WVWZZZ3DZ78003242 .

[1611AZTEC]

Thanks for the response Crasher. VIN WVWZZZ3DZ78003242

[Crasher]

Remind me Monday, I need to be at work for this. You can post the scan by saving it as a .txt, copy and paste… simples.