I have a '09 GL550 that has around 105k miles. The ADS has started acting strange for about a month. It started after I had it set on sport for a day or so. The right front went down to low level which in turn puts left rear high not to mention ride. I changed the level adjuster on the right front, seemed to fix problem. Then it started doing the same thing again, but when I would stop, I could see the right front level to normal height but would lower when up to speed. At first it would be level when at rest sitting in garage, not leaking down, but it's down on right side. I have done all the leak checks have found none. The function lights on panel don't light up now, sport and comfort. I did get a malfunction on dash, I also checked codes 7E8 and 7E9. I wonder if it could be the control module, if so where is it located. I hate to keep throwing money at it and not fix the problem and really don't want to change to regular struts.
Sorry about the lengthy post trying to give as much info as possible.
Thanks in advance Ed

 

What do those codes mean?

It's never a good idea to throw money at things - always try to diagnose. For example... that level sensor... it could simply be the arm (ball/socket) that's "sticky" from crud. Pop them off, clean real well, reinstall with some grease.

You mentioned you didn't "find" a leak, yet the right side went down? Overnight? That's a leak somewhere. How did you check for leaks? I'm sure you've read other threads about finding leaks and checking at various inflation heights.

With the vehicle at normal ride height, do you have any issues?

Try driving with the compressor relay removed, along with the ride height sensors disconnected. If it still drops, there's a leak. If it doesn't, the problem is electrical/mechanical (but not a leak).

 

I have no idea what the codes mean.
All sensor ball sockets have been removed and cleaned and greased.

It was up when I got in the car, it went down while driving, this has happened before but when speed slowed or sitting at stop light you could see the right front visibly raise to normal height. This time it did not raise back to normal height. It's not that it went down over night it didn't raise back up after stopping, even when trying to do it manually. The light will flash when pushed on panel and the sport/comfort switch lights don't come on now. It does have a new manifold for ADS.

I checked leaks with soapy water spray on all lines and bags extended.
right front won't stay at normal ride height and now doesn't raise manually

 

OK, it's a little confusing trying to follow what you are saying. For example: "The light will flash when pushed on panel and the sport/comfort switch lights don't come on now." That sounds contradictory. How about "It was up when I got in the car, it went down while driving" -- what does that mean?

Try this - don't mess with any of the buttons - just leave it on the normal setting (possibly for a few days, if needed) and see what happens. In the meantime, either find someone with a better scanner that gives a description of the codes or try googling. They may have nothing to do with what's going on. Did you clear the codes? Did they come back?

When you said "it didn't raise back up after stopping"... did it "need" to? Meaning, was it noticeably lower? Maybe it was already at the right height? Have you gotten out and looked... comparing the distance of the gap between the top of the wheel and the fender?

 

Plain and simple. The problem started, right front drops while driving, does not go down overnight. It used to raise while stopped at red light it would raise to normal height. As soon as I started moving it would deflate. The deal with the panel just started, the sport/comfort lights don't come on, if I try to use the switch to raise it manually it flashes and vehicle doesn't raise. I did clear codes, can't find anything helpful on internet. It's not that it went down over night, it never did leak down over night. It failed to raise to normal once at idle or stopped at light, it always raised to normal when pulling into garage.

Yes it is noticeably lower, all the way down, don't have to measure, it is not at the right height. The fender flare is below level of tire. I wouldn't take a chance driving it in this condition.

 

OK, yeah, that is quite low. I did a (very) quick search for those codes and it was coming back engine/tranny stuff - but don't rely on my searching skills! Try the thing I mentioned above (if you can first get it to inflate somehow). If there's no leaks, you should be able to drive around normally, at least. It should help get the "diagnosis" going in one direction or the other, anyways. Might be able to jump the relay to manually power the compressor - but I'm not sure what else is involved with it turning on - possibly disconnecting the level sensor arm and manually playing with the sensor? Another thought... try swapping the level sensors.

Those are all just random "work around" type thoughts. But if you have a scanner that would read MB systems (MB II, for example), it can tell you a lot of things as it reads the various sensors (live). More advanced scanners (STAR/DAS) can probably get into the electronic control boards.

It might be worth paying a local Indy for an hour of their time to properly diagnose - if you're not comfortable doing those "work arounds", anyways.

 

Thanks I'll try these, I got the same thing on the codes. It has a new level switch and valve block on it. I can hear the compressor running and the valve block working, i.e a ticking sound. I'm kind of afraid to drive it since it won't stay inflated while driving. I don't have a problem doing the work, used to build street rods and hot rods. I do know a shop that works on Benz's exclusively. Thanks again for the help.

 

Good luck!

 

In addition to replacing the front right sensor, have you inspected the harness for damage?

If it isn't a leaky bag, then it's probably a malfunctioning sensor - and that fault could be anywhere from the sensor itself all the way to the central computer gateway, or anywhere in between.

Those codes don't mean anything to me - did you have it read with an MB Star / DAS tool? It should in plain english tell you what it is seeing that is wrong, no code translation needed.

What it also can do is give you a live readout of the level sensors - so rocking the car back and forth and seeing how the right front compares to the others is a good way to rule in or rule out that the sensor is the root cause.

 

FYI, this is the scanner I have - while not as "intelligent" as STAR/DAS system, it can do quite a lot - as I mentioned above, it can show live data on the level sensors. https://www.icarsoft.com/Product/s-3...oft_MB_V2.html (It's the newer version of the "MB II" model that you can see mentioned on forums regularly.

Max - absent a scanner... what are your thoughts on the idea of getting things inflated, then disconnecting the level sensors and driving around (and possibly removing the compressor relay). Without the level sensor input, there "should" be no changes to the bags, right? It should take the variable of "level sensor and all wiring" out of the equation, right?

 

Max--I did inspect the harness it looks fine. It was cheapo scanner, but I got a new iCarsoft MBII today. I'll get a readout tomorrow and post findings. I messed with it some tonight but the only two I remember, strut implausible, I think this is telling me it's extremely low. Also said compressor was slow to pump up, maybe a weak compressor? I'll get a better reading and post.
Thanks

 

Dennis-I got a iCarsoft MBII today. I'll get some read outs in the am and post. Has the relay got a slot number?
Thanks

 

Yes - think you can do that by just pulling the airmatic fuse...ie not the compressor fuse.

if the system exhibits the same behavior you then have a leak.

 

Ran a scan on the GL550 this AM

DTC 5505 1. Recovery times during filling of the air suspension strut is too long.
2. Suspension strut is implausible
Datastream
B22 Left Front Sensor 3.57V
left front -2.756 inch

B22 right front 0.82V
Right front -4.331

Left front vehicle level -2.756
Right front vehicle level -4.331
Vehicle level @ rear left -1.260
Vehicle level @ rear right -2.00

Left front acceleration sensor 2529.41mV
Right front acceleration sensor 2529.41mV

Y36b1(AIRmatic pressure sensor) 22.92 bar

Left air spring is completely empty. This is what's a confusing, the problem of the air bag completely deflated. It was going down when driving and would fill back up when stopped or parked. It wouldn't leak down over night, just go down when driving. The bag being completely deflated started when I changed the block valve out, could It be bad. I'm thinking about putting the old one back on.
Thanks again for all the help.

 

Which is your problem strut - left or right?

Have you checked for leaks at the airbag and the valve block?

 

The right side. I have check block valve and strut with soapy solution, no indication of any leaks.

I changed the level indicator switch out, took the new one off and put the old one back on and the right side pumped back up. I Haven't drove it yet. let it sit over night and see how it looks in the morning.
Readings after changing out switch in inches:
Left front -0.984
right front -1.378
left rear -1.457
right rear -1.339

With engine running:
left front sensor 2.78 v
-0.984 inches
right front sensor 2.12 v
-1.378 inch
left rear sensor 1.92 v
-1.457 inch
right rear sensor 3.06 v
-1.339 inch