rgrewal

Hello,

My daughter has this 05 a8 and the front suspension bottomed and the compressor would not run. I have done the following ( I do not own VCDS yet)

1. Jacked car and checked for leaks with soapy water, found leak on R side and have replaced with used unit with no leaks
2. Replaced and tested relay, old relay was good and would send power to compressor that build decent pressure with finger/thumb test.
3. Checked 40 Amp fuse and it was good. (also have removed cover on old relay to test pump as it does not activate on key on)
4. Will replace solenoid block with used today.
5. Checked wheel sensors and they send signals that will turn on/off the green warning light
6. The car lowered fairly quickly and would not come up again in the front

Here is the problem, they air system is NOT sending any power to the compressor, I can hi-jack it and close the connection on the relay and it send power but it appears to not send air to the separate wheels at all, thus the leak in front lowered the front it appears to not send air to the front. If I turn the key with the green light on, no compressor (includes full start, yet the relay is good ect....)

So I was hoping for help....again without VCDS. My thought were to simply change the Module as well (Please locate module)

I have two of these cars now and will have to buy something and also wondered if the new OBD II readers

My thought are that is it the suspension module and or the solenoid block

Thanks a bunch

Ritchie

the_duke

My first step in diagnosing this would be to pull the codes with VCDS. But you don't have VCDS so you're just guessing. If you replace the module you'll need VCDS to recalabrate the system.

rgrewal

Thanks Duke In MT, used to live in Whitefish and had good times in MT.

1. Well it still may be a relay as all I could buy was a napa relay but I will pull a relay out of an 04 A8.

2. Next I have to check the 10 amp fuse for continuity as the 40 amp is ok.

3. Then I will check the relay pins for output voltage from the control....Not sure which is what but I will try.

4. Then I will either buy a VCDS or Xtool VAG401 VAG diagnsotic tool for VW/AUDI/SEAT/SKODA Not sure if a VAG 401 will re calibrate the system or if VCDS lite will but will all Ross Tech

5. It has to either be 1. relay 2. Pump solenoid 3. Control unit,

Kind of a bummer as I have a differnt problem that anyone I can find on the internet


Thanks

ltooz_a6_a8_q7

To troubleshoot the problem, you don't really need VCDS, in my case, it didn't show anything. Just try to read and understand the system. Don't replace parts blindly. This is how I did mine and it cost me ~$300. Even I have VCDS and I didn't need to calibrate anything.
https://www.audiworld.com/forums/a8-...rider-2913592/
Cheers,
Louis

rgrewal

Thanks so much,

I have viewed hundreds of pages including the self learning stuff and followed everyones posts and really narrowed it down, but I still have the issue that not many have had with the D3 A8:

1. Turn key to car and no compressor but jumping it works with either stright 12 v or by pulling cover on relay and pushing it closed.

2. Put new relay in and same

3. So it has to be either new relay was bad or control unit is not sending message to run compressor.

Tomorrow I put more if back together as it had a leaky strut that I changed but just had on the engine as you did.

I will get it but the problem is a bit different.
Thanks

Ritchie

ltooz_a6_a8_q7

To find the problem, you need to understand some basic.
1. Jack mode, leveling system is turned off so not both of the struts won't go down to the lowest level of the strut.
2. Lift mode will raise to the max.
So, if the pump is good, as soon as you turn on the car, set to lift... when the car raised to max, turn on jack mode.
Whatever goes lower is the culprit.
Louis

rgrewal

Mr. Louis

I think you have it I forgot to switch off Jack Mode and of course the pump will not fire in Jack mode right?

How many times did I see that and not do it.......I must be an idiot.

I already found the leaks per your video but wanted to avoid the VCDS, although I have two D3's now.

Will try in AM, so much to think about I forgot the MMI interface can shutter the pump.

Whoever engineered these cars must have been friends to the gods

ltooz_a6_a8_q7

Yes, Jack mode turns off everything, even the pump. It was noted in my Video.
VCDS is a great OBDII reader and some hacks that people used to break their cars if they don't use it correctly.
I've used about less than a hand full since I've had VCDS.
People have no idea what the word "CALIBRATION" means - I've seen many people "calibrated" the system and break it in the process because they didn't follow the "hack procedure" correctly.
As an engineer, when I calibrate something, I must have a GOLDEN device or KNOWN GOOD reference to calibrate the device with. How can one use VCDS to calibrate the system when there's NO known good device or references to compare to. Calibrate against some readings of a broken system?
I did use the VCDS to add some devices when I retrofit my back up camera and retract the rear eBrake. I could use a hacked OBDII which I bought for $20, but I still bought the original one for $350, just for good karma... My car seldom breaks.
If you want to keep owning Audis, it's good to get one or any alternatives if they're cheaper. Yes, sometimes it's good to be able to reset things, but now they start selling with bunch of options, you can find a used original one for less than $250. I think the technology now is bluetooth with IOS or Android, I hate Windows. I'm testing the ELM and some free programs.

Cheers and good luck,
Louis

rgrewal

Dear Mr. Louis,

Thanks so much for your reply. I forgot to mention the car had the exact problem you have except the compressor will not run unless jumpered SO FAR. Of course the car was NOT in Jack mode at the time and I have not tried it out of jack mode as it is on jackstands with several air lines disconnected.

My guess is based on reading the AUDI service is that (MAYBE) the controller is simply withholding the signal as it says it will do, due to leak detection to save the system........

1. The question remains and you cleared it up as to what you would do to the car after pulling and clearing codes.
2. The cars is supposed to self clear codes after a certain time, so maybe I have to drive it, get it moving, then jack it up and try to fill it. (not withstanding filling it first with some air)
3. I understand with VCDS you can run a DIAG on the system and that it can stop halfway through leaving you stumped.
4. If anyone knows the exact procedure to calibrate let me know. I have reviewed the process from Ross-Tech.
5. Again, I have power to the relay, changed it, but the old one looked good so I figure it has to be the controller in it;s state of system shutdown.

Thanks again Loius



On another note years ago I bought an 04 A8 that was thrashed for a few grand and it eventually totally died. I took it to the dealer, where i had a friend in the service DEPT. He worked on that car pro-bono for a while and was stumped.......finally after giving up he hooked it up with GERMANY and they found the problem and I sold it later on trade for about $5K.

ltooz_a6_a8_q7

Why do you think calibration unlocked the pump? The pump is turned off because the system sees something fatal and turns it off to prevent further failures.When you replaced the used strut, did you miss anything? all the wirings are correct? People always break thing in the process due to doing something else that's not necessary due to NOT understanding why they did it.
The system is self managed unless you programmed something a locked register of the memory like "calibrating" it. Trust the software of the system and throw the VCDS away.
Just hook up everything exactly as it was originally, turn on the engine, make sure the battery is good, if the battery is bad, it will turn off the pump also.
Give the system sometimes to get back to original program and settings. Always leave in lift mode any chance you get and do not change it.
When you changed the strut, you must have done something for the controller to turn off the pump.
Always go back to the last working condition.

Cheers,
Louis