Redline21

My suspension has been fine until I was coming home the other night. I turned onto my street and there was unplowed snow on the road so I pressed the button to raise from level 1 to level 2. The compressor came on and the green L2 light started blinking but it never got to L2 and then I got the orange dash error light. I pressed L1 and it appeared to go back down. I was home by then and parked in the garage and forgot about it. Today when I went to drive it however I found that the rear was bottomed all the way out and was on the bump stops. I couldn't get it to raise and the compressor was not working at all. I found that the 40A fuse under the drivers side dash was blown. I replaced in and the compressor started working again. I thought I was back in business with an easy fix but sadly no such luck. Even though the compressor runs the rear never rises on either side. I tried jacking the back up and letting it run but that made no difference.

Initial VCDS fault codes:
01400 - Suspension Level Control
11-00 - Control Limit Not Reached
01772 - Signal from Level Control Pressure Sensor (G291)
27-10 - Implausible Signal - Intermittent

VCDS fault code that comes back after clearing:
01400 - Suspension Level Control
11-00 - Control Limit Not Reached

I'm not sure where to go from here. It doesn't seam plausible to me that both rear air bags would go out at the same time to the point that they wont hold an air. It also seems unlikely to me that the compressor would suddenly fail. It has been working as far as I know, though I usually leave the car in L1. What should my next step be? Any other daignosis I can do? Should I just try rebuilding the compressor? I need to get the car back on the road asap but I'm guessing it's not a good idea to drive it in it's current condition.

Redline21

I the car jacked up last night and cranked the garage heat hoping it would make a difference but no luck.

In thinking about this more I theorize that the car tried to go to L2 but failed for whatever reason. I then told it to go to L1 and it complied and released air from the bags accordingly. For some reason the fuse blew and it never stopped releasing air from the rear bags and let them go all the way down. Is this plausible? How does the air get released? Is there a pressure release valve of some sort? Could it be stuck in the "open" position even after replacing the fuse?

G0to60

It could be that one of the valves got stuck. I'm not sure what's going on but here's a good reference on how the whole system works.

http://www.volkspage.net/technik/ssp/ssp/SSP_243.pdf

Redline21

Well I installed bagpipingandy's compressor kit today hoping that would help. Afterwards I was able to confirm that there is air flowing through the lines to both rear bags, but it doesn't seem like very much air. I couldn't feel it with my figers at first (possibly because they were cold and dirty!) but I stuck my face next to it and could definitely feel air coming through. I'm not sure if this is normal or if there should be a lot more air pressure?

I reconnected the air lines and could visibly see and feel the bags inflating slowly. However they don't seem to inflate past a certain point. They have firmed up quite a bit are still somewhat soft when I squeeze them and the car never rises.

I read through the suspension manual which has a lot of good info, some of which is over my head. I'm not really sure where to go from here. Could the bags be leaking air out as fast as it is going in? They never leaked before but I suppose every leak has to start at some point in time. Or am I not getting enough air pressure through the line? Or is there another component that could be the culprit? I'm still not sure why the fuse blew in the first place.

johnak210

Hi Redline21,

The air suspension is pretty complex and guessing is going to cost. You need a good diagnostic tool, or vcds. Some of the less expensive ones will not show all the diagnostic info that you need. Check craigslist or whatever to see if someone in your area will do a reading with their tool - usually for a price.

There are some air suspension related problems that can be your problem, besides those offered by others. For one, the air bags don't last forever and will leak with age. Sometimes a visual inspection can see the problem. Also there is an o-ring seal that can leak air. Another is the sensor(s) could be bad. Then there is the wiring issue that is somewhat common to allroads - the wiring breaks or makes intermittent contact where there is a sharp fold and sensor communication is lost. This fold is in the rear passenger area and is close to or under the rear seat. Sometime you are lucky and the break is visible. If not, you have to trace from the sensor to the level sensor control.

The air lines are thin with a limited capacity. You may not have left the pump on long enough to even partially fill the bags enough to start lifting.

These are some hints. Online there is a lot of info including images, diagrams, etc. Good luck.

Redline21

@johnak210

I have VCDS, see my first post for problem codes.

You listed a lot of the things that could go wrong with the suspension, but what in particular would be the issue in my case? The sensors should be working as the compressor runs and tries to inflate when the key is turned on, so the system does know that the bags need air. I used a regular air compressor to shoot air into one of the rear bags and it inflated so a bag leak shouldn't be the problem here. I have let the compressor run 8 or more times in a row and the back still isn't lifting at all, so I doubt that is the issue.

At this point I would guess that either the compressor still isn't generating enough pressure to do any good or that air is being released from the system by whatever tells it to release air normally.

bagpipingandy

Hi, all the info you describe i think still points to a weak compressor, it doesnt explain why it suddenly happened when you turned into your street, has it slowly been deteriourating?

but for now the symptoms still sound like the compressor, what condition was the cylinder when you fitted the kit? did you fit my kit (bagpipingandy)? a lot of chinese copies now exist from other people and do not work well at all.

Check the piston ring is fitted up the correct way, the pressure should "feel" good coming out of the compressors outlet, no1 1 reason for poor pressure is the piston ring upsidedown,

let me know if it all checks out ok, and then we can try other things

regards

Andy

johnak210

Unfortunately there may not be "the answer". I solved a suspension problem before when I found broken level control wires under the back seat. Whoever did some service before I owned the vehicle moved the cable enough so that the rear seat severed cables. PITA solution. Another problem I had was that someone removed the air hose from the passenger rear air spring and put it back. That person did not reinsert it far enough so that there was an air seal when tightening the nut. Easy fix. It turns out that I found the real problem that caused the passenger rear ride height to be either too high or too low. It was the level sensor. It developed a hole between the lever and the body. Only noticeable if the sensor was removed and the lever was moved to expose the hole. If you shook the sensor you could hear small particles bouncing around. Anyway, sensor replaced problem gone. Along the way because the compressor kept on pumping away I did need Bagpipe Andy's rebuild because it was taking too long to go between levels.

The Allroads do have a problem with the wiring for the level control. That is by the passenger rear seat. It breaks. But that was not my problem.

So, from my viewpoint I was only trying to encourage you to do some detective work. In my case (and for many others) there wasn't "a solution". I hope there is with yours.

Redline21

I have only had the car for a couple of months. The compressor seemed to work OK when I bought it, but I typically always left it on level 1 and never raised it so I can't really say it it has been slower than "normal" as I never got a good feel for what normal should be or how quickly it changed between levels. I would guess that it took around 30 seconds between each level. That is just a guess and I don't know how that compares to a 100% functional system.

I did buy your kit on ebay via your US distributor. I paid close attention to how the ring fitted and made sure that that notch fit around the little pin. The amount of air coming out of the lines to the two rear bags is barely noticeable. It sounds like it should be more significant than that so I would tend to agree that it is most likely a compressor issue.

At any rate, it has been two weeks and I am not making any progress in spite of extensive reading online. I really need to get the car back on the road so I made an appointment to have my local shop look at it as they are quite familiar with these. I just hope I don't need an entire new compressor as it looks like those are in the $400-$500 range! Are the Arnott's considered to be the same quality as the Wabco's?

bagpipingandy

Hi, the arnott units are wabco compressors they are just a disributer, but on some units you have to cut and join cables just so you are aware, if you have the tools it is no problem, dont jump into new compressor yet

a brand new compressor the car should lift in approx 10-15 seconds anything around 20 seconds is good also for lifting each level (when stationary), if it takes 2 mins this is the time out and would put the error light on,

what condition was the cylinder in, any scoring?

does the fronts lift ok?

strange it happened overnight this would make me think maybe another problem, but if it is the compressor and you have time i have lots of spares to help fix compressors but i understand if you need it quick a new compressor may be the fastest route.

Get it checked out 1st, little air to the rears is either weak compressor, valves or airlines restricted, if the front is also slow to lift it points to the compressor, if its the rear only with the issue then it is something else

regards

Andy