Another mysterious Airmatic Malfunction thread
 

Does the compressor sound louder than usual? How long does it take to go from normal ride height to raised level?

Main or aux batteries on their way out?

The compressor does not seem any louder, nor does it seem to take any longer than usual to change the vehicle height. As it does not have the option to switch between 'sport" and "comfort"modes, I would assume that the system isn't constantly monitoring body roll, etc., and adjusting the suspension--maybe I am wrong in that assumption.

Funny about the battery--I'm the second owner of the vehicle (purchased with 19k miles), and I do not believe the battery has every been replaced. Have been thinking recently, that for no other reason than age, it might deserve replacement. Strange thing is, that the malfunctions typically pop up after ~20 minutes of driving, and you would think that even a weak battery would be thoroughly augmented by the alternator by that time--eh?

thanks!

Well, I am beginning to suspect the compressor. Tried "exercising" the hi-low suspension settings today, and found that it was somewhat inconsistent with the height the vehicle would rise to, varying by about 1/2". In some cases, if the ignition was turned off and on again, the compressor would start back up, as if it were trying to complete the rising process, and it would get another half inch or so. In one cycle, the malfunction message came on again. So I guess I will take it into a shop that can do an official diagnosis, just to make sure I am not replacing a compressor, when it is really the valve block that is at fault.

Try removing all fours level sensors, clean the ball and socket real well, then pop them back on with some grease. Might just be a sticking level sensor... and this is at a least a "free" check and should be done every so often, anyways.

I have a 2008 with the enhanced off road package. I was getting a 'Malfunction' code in the message box and it turns out that its a sensor in the rear shocks saying that the rear shocks need replacing. I'm having this done as I type this. The compressor was good and when I went to raise or lower the truck, it did it, no problem. However, the truck was stuck in sport mode and would not let me change the setting to comfort or normal. The total cost for the new rear shocks and stuff is $1500.

so you have ads (advanced damping system) and whoever is replacing your rear shocks pulled a code stating they’re bad? I did not know that they had that capability built in, but with your symptom it is plausible.

did they leak any oil?

Yes, I have ADS. I didn't ask about a leak but I will ask when I pick the car up. I actually thought it was just a faulty sensor. I replaced the air bags about 60K miles ago and thought I should still have some life in them since the truck wasn't losing any air on any of the corners. The truck has 140K on it and it's in fantastic shape body wise. AFter this, I just need to do the front control arm bushings which is going to be a pain since you just can't replace the bushings. You have to replace the whole control arm. :( Gonna cost another 2K.

Well, I took the GL to a local chain auto repair place near my work. They reported back that they had a heck of a time figuring out what was wrong (but didn't mention any of the codes that they pulled from the system). Claimed that they did a bunch of testing and established that the entire air system is just fine, but that the front struts are worn and have too much travel, and this is what is causing the malfunction. Does this sound plausible?

nope. There will be either a record of compressor excessive run time, stored or active code for compressor overheat or stored or active code implausible signals coming from one or more level sensors. Your description makes me think these guys don’t know what they’re doing - something could have been lost in translation though.

The majority of airmatic issues are caused by leaking airbags not replaced immediately, which makes the compressor work overtime and eventually burn itself out which triggers a malfunction.

the minority of airmatic issues can be attributed to physical damage of the level sensors so that they are giving incorrect or implausible level signals which also triggers a malfunction.

And the plot thickens...When I got the car home tonight, I raised the vehicle level, and the compressor ran for a while, the vehicle barely rose, and eventually the "compressor cooling down" message popped up. With 2 or 3 successive tries, I got it to the (mostly) raised position, then lowered it and tried again, got another "compressor cooling down" message. Today, it seemed to take excruciatingly long to get to the proper high level ride height. Starting to feel more confident that the compressor is running until the motor overheats, but air isn't getting pumped.

The conclusion that the struts need replacing just doesn't add up. The bags were all replaced around 20k miles ago, and don't appear to be leaking. Even if the shock absorbing portion of the assembly was "sagged out," seems like the air bags would compensate to arrive at the correct ride height, and the system would not notice until I try to raise to the "off road" level. Speaking of which, can anyone out there tell me what the spec distance from the top of the tire to the arch of the fender should be when the vehicle is fully raised?

Having noodled on this issue for another week, I am starting to believe that the compressor may be worn out, but it isn't the root of the problem. If the car is left sitting, the air shocks do not leak down, but what about if I am driving down the road? So to test the theory, I unplugged the 40A fuse for the compressor. No malfunction indicator came on, but, sure enough, with a fairly small amount of driving around my neighborhood, both front and rear levels dropped dramatically, and unpredicatably (ie, for one test cycle, the front dropped, and for the second, the rear dropped, always in pairs). So either the bags are leaking, but only leak when in motion, or the stinking valve block is leaking, and the dynamic changes in force encountered during driving force air past the o-rings in the valve block, when they are able to hold the static pressure of a parked vehicle. Will tear into it tomorrow just to double check all the connections and bags for leaks, but I'm thinking it is time to order some parts...

OK, you probably saw that other recent thread where removing the 40a relay was part of the "figurin' out". In that thread, we also talked about soapy water. IF you're compressor is timing out, it's either shot or there is a leak - start spraying soapy water everwhere the compressor pumps to. It can't be a line or a connection on the struts/bags as those would continue to leak after the engine is off. In that thread, there was also talk about computer diagnosis - that may be a direction you want to head before just throwing parts at it.

No--I didn't see the other thread--can you provide a link?

Yes, I will do the soapy water treatment tomorrow, I suppose there is a possibility that the Arnott bags have leaky spots in them just like the originals, and by flexing them during driving, they leak. Hard to reproduce the driving flexure while under the car with a spray bottle, but will give it a shot.

Definitely didn't want to just throw parts at it, which is why I took it to the garage to get the codes read last week. But, I didn't get any actual codes out of them, and I now seriously doubt they know what they are doing. Anyone out there with a favorite code reader? Saw an Autel MD808 that might give me what I need in terms of diagnosing these issues, but can't be sure.

Have you tried leaving the vehicle overnight in the raised position? Or at least, as high as you can get it. The height flexes the rubber differently and may show the leak.

The other thread is a recent one, like yours. You'll see it in the thread list.

Here it is
https://mbworld.org/forums/gl-class-...eshooting.html

Yes, I can leave it sitting in the raised position or the regular level for days, and it doesn't seem to sink at all. It is only during driving that I get the Airmatic Malfunction symbol. I am theorizing that the only time the system is losing air is while the car is in motion. This could be from the bags flexing, or from the changing pressure in the air system squeezing past the orings in the valve block. Leaking airbags seem unlikely, as it is only 20k miles since they were all replaced with Arnotts.

Well, this morning, I took each wheel off, which resulted in the airbags stretching out to full extension. I then bathed each bag in soapy water, all connections, exposed the compressor and valve block and bathed them as well...and found no leaks (at least observed no bubbling).

So I am still very suspicious of the valve block, but I think I'll buy a scanner that can get at the details of the codes. Might ask for my $140 "diagnostice fee" from the indy shop that I took it to last week if it turns out to be something different. They quoted $5k for doing all four airbags (which only have 20k miles on them).

Thanks expl0rer for the link to the other thread. Sounds remarkably similar, suggesting getting the codes is critical to this process.

I see how it is. I didn't do your homework for you so I don't get a "thanks"? ;)

$5K for bags all around?!!? I understand that MB dealer prices are higher - more overhead and all - but that's just ridiculous.

My apologies--a hearty Thanks to whomever is willing to listen to me whine and offer some suggestions.

So I pulled the 40A fuse and drove around the neighborhood again, and finally got the malfunction icon. Looks like the rear end is sinking today. The thing that I just haven't figured out is that the valve block has a solenoid for each wheel, one for the compressor, and one for the reservoir. So I am confused as to why when the car sinks, it seems to sink on an axle, not on a singular wheel... Also, the hose from the compressor to the valve block is quite large, the hoses to each of the wheels and the reservoir are all the same (tiny) size. So when the vehicle is lifted to its highest height, and I lower it, does all that air go into the reservoir? Seems like that reservoir would get full eventually, and the system would have to vent.

Just bustin' your wheels a bit on the homework!

The malfunction is probably nothing to worry about - it's just complaining because it can't do what the level sensor is telling it to.

When one side lowers because of a leak, the other side might be lowering due to weight transfer. When my front right was leaking, it sometimes looked like my front left was, too.

If it were my vehicle, I would start throwing parts at it. It's a 12 year old vehicle with a complex air supsension, well known for unreliability.

Hi, I had a problem like that last year in my 2007 GL500, it was a problem with the harness conector of the suspension sensor air shocks, just take a look at then.
Here is the link of a this part for sale on e-bay: https://www.ebay.com/itm/68K-MERCEDE...YAAOSwx-9Wz3Tc
And here is the photo of the part that had was giving the message to me:

https://cimg3.ibsrv.net/gimg/www.mbw...7fe89d202b.jpg

Codes are key. Every job has the right tools, for us home based mechanics a good code reader for these cars is paramount. And you're welcome, but I didn't do anything, really. :)
Transferring thanks to Dennis' account :)