CaliBenzDriver

Daren to answer your PM request: you're in good hands here!

You nearly know as much as me about MB AirMatic. I have steel springs


height sensor

I ve just found out that I too have a HL Level sensor on my driver side rear axle and my HL LED module has an active fault about it. I was surprised because it seems my non-active LED does have an up/down actuator.


The neutral position must be LEARNED at least once

So then I started poking with my scanner.... it appears to have a reset type of learning procedure to initialize the ride sensor.

Locate your AirMatic cheap AIR FILTER and change it... in addition realize that air moisture freeze into expending ice and the air valves are not rust-proof if your compressor keeps pumping up any size leak, fix it and drain condensate.

Height Sensors are contact less just like the accelerator pedal sensor, no potentiometer wiping a fragile carbon track.

In addition to rusted articulated steel ball joints.
I bet 90% chance these sensors use solderless pins to ensure they require replacement.

Inspect the harness connector to sensor. Use silicon RTV to positively seal harness wires. You don't want your exposed sensor to go to waste soaked like Blind-Spot modules.


+++ stupid part naming translation call these sensors: "rotation sensors".

S-Prihadi

Just like Cali said, I am here by your PM.
But I never own a car with airmatic, so I can't contribute anything good for now.

In the mean time, give me your VIN. EPC and WIS wont work very well without a VIN.


For today, I am assuming your car is 221.071 chassis code and is using M273 engine because you mentioned S550 and WIS pointed me S550 is using M273.
I must use some sort chassis code, for EPC/WIS.


I will try to answer some of your questions or assumption :

You wrote in post #16
=====================
So in theory, the level sensors are likened to potentiometers that send a signal to the ECU to turn the air compressor on and this triggers the airbags to fill or air out. The higher the voltage sent from the level sensor the higher the car lifts upwards and vice versa. When there is a problem with this system, the air compressor just stops working to prevent any movement of the air ride therefore causing the owner to cease driving the car and fix the problem??
===================

For the text I colored blue.
Never assume that is the way the level sensor works, it could be that the rear is using lowering voltage for raised height. Too bad there is no information on WIS that I could find.


You better get a better scanner with bigger screen, the icarsoft is simply too slow and is not as good MB software wise compared to Launch.
This Launch is what I recommend you to get : CRP919E

If the chassis code I use W212.071 is correct and indeed you suspension code is 489, your car only has 1 REAR LEVEL sensor, yes, only 1.
But hell.... this code 489 has 3 acceleration sensors. I think it is because this is S-Class airmatic of a higher status than W212 version.
Code 489 is probably adaptive , hence the name semi-active.





..

Below is I believe a software LOCK, because the Airmatic module knows your car is being jacked up.



LOCK 101





If you do not yet own a knocked off copy EPC/WIS, get one immediately. Year 2020 version is good enough.

Don't troubleshoot with blind document support.
S-Class is probably more complex than W212 hardware wise, it has to be, it is a more refined ride car.

I give you an example, this video is about Airmatic but it seems it is for less advance Airmatic or chassis.
Master Lou described 4 level sensors.

While I believe most so called Mercedes Airmatic ( not ABC ) would be similar, but they may not be 100% the same between lower priced models to an S-Class.
So always refer to WIS.

Attached what I can dig out of the WIS for your use.
There are actually a lot more, but today I am sick of reading documents. I have un-happy issues with some imported parts for my friend M271.8 engine and my eyes are tired.

Change their titles to reflect the actual document content.
WIS is stupid when it comes to print out and in XPS too. So it is easier for me to make v1 to v7 to a 1st printed title and correct the documents later.


Have fun............

BOTUS

interesting link

so if the air tragic set up loses the plot - it can only get over itself if it decides the front wheels are driving - what utter morons

the other bit about one sensor and then three - is one rear, two front = 3 (the fronts do side to side and front height)

S-Prihadi

Wheel speed sensors and all others will communicate with airmatic. It is not as simple as one would think.

N51 is the Airmatic module, the rest are its supporting team.




I don't know if you often read MB WIS or not, amazing complexity overall some of their system are.
This is why for now, a W212 is far as I want... not any newer models with more complex system and needing a Xentry with higher level permission...Dugghhh.

When the VIN is available, we should know better the actual system in use.

S-Prihadi

I hate MB Data Card and the WIS !!!!!!

W212 S-Class standard suspension is called Airmatic and Code is 489 , but data card will not show code 489 as it is not an option, it is standard
So while a techy is trying to identify this M278 engine W221.173 S500 CGI as the official name in WIS/EPC ( please don't ever call this S550 ) and he comes across the WIS below :





Easier to read this way.... MB love for the word EXCEPT can sometime trick you.



Why dont they simply write this way :
Code 489. For model W221.0 / 1 and W216.3, as of model year 2009, modification year 8.
NOT VALID FOR CODE 487 ABC Active Body Control

Now techy got confused, how come Data Card does not have Code 489 ?? and WTF is a Modification Year 8 ?..which is not in the data card.


Ultra's S500 datacard.


Dang, I just realized the data card date is US version MONTH-DAY-YEAR . Date format between DAY-MONTH-YEAR and US system can screw you in WIS wiring diagram if the original
German version is there with DAY-MONTH-YEAR in numeric only.

So where is Modification Year 8 information ? What is it actually ? I don't know.


From suspension system in EPC it is a different way to see suspension type.
It is ELIMINATION method. The code you see as MINUS -487 for item #10, it means it is NOT for code 487... LOL. This is the numeric version of EXCEPT MB love to use in their WIS instead
of NOT VALID FOR XXX







So there you go... your suspension is indeed Code 489. But I can't find 2nd printed document ( yet ) mentioning 489..... aside from that WIS.

I seen total disconnect between marketing brochure , engineering WIS and EPC of MB often.
The same item can be called a few different names. The key is to see the Code , but too bad like in this Airmatic Code 489, only WIS mentioned it as 489.







Now for giggles. Two different persons probably made these 2 documents. Imagine if you don't have Code 489 as an identifier, won't you get confused reading the description ??












Happy fixing your car.....

Ultrakla$$ic

THIS x1000!!!!



Code489....no Code 489.....Air suspension with continuous damper adjustment.........semi-active air suspension....


Me right about now!!! LOL

Ultrakla$$ic

Plan of attack this afternoon, so any input/suggestions are much appreciated

1. Undo negative battery terminal
2. Assemble rear lowering link on new sensorand spray with electrical spray or use dielectric grease to prevent water intrusion and place back on vehicle
3. Reconnect battery
4. gently lower the car until wheels barely touch the ground but do make contact
5. start the car with door and hood closed to prevent ECU "confusion"....lol
6. Wait/pray the airbags fill and sensors communicate with ECU
7. lower car and pray its fixed

CaliBenzDriver

I would leave out the part about dielectric grease and spray only the harness side a little excluding the module side where solderless pins likely in use.

Spraying that side would reproduce "oil-in-harness" issues...
🤞

Ultrakla$$ic

Will do Cali! Thanks!

Ultrakla$$ic

Well the new rear sensor did nothing to fix the problem. HOWEVER, the "COMPRESSOR LOCKED DUE TO ON BOARD VEHICLE NETWORK EMERGENCY MODE" is not locked out anymore.







again, however, the voltage for the rear axle level sensor is 0.49V and the front voltages are way more as noted here:






A lttle bit more info, my compressor is not kicking on AT ALL!! No codes to report and my compressor will not turn on at all so no way to check for air leaks even if I had too.
Another weird thing happened, my wife rolled down the 2 front windows while sitting in the car so she could hear me give the commands to start the car and when we rolled the windows back up, the passenger window rolled back about 1/3 of the way by itself and stopped.

Questions:
1.I checked my big battery and it seems to be good with voltage and % of life. What does the AUXILLARY BATTERY run in the car? The air compressor? Windows???
2. What if my RELAY in the fuse box is blown that controls the air compressor??
3. Does it sound like my compressor has died since it will not come on AT ALL?????? The 40amp fuse is good but I will have to wait for my son-in-law to check the relay and maybe try to jump the air compressor??????

I'm kinda feeling a bit defeated as I was really hoping the rear level sensor was the issue....

Ultrakla$$ic

So I think the window issue was because I disconnected my negative terminal to do all the work and I needed to reset the pinch protection/ anti-entrapment feature.

Now, is my compressor and/or relay dead????

CaliBenzDriver

Yes, the windows that backs down needs to be retrained. Look at that simple function in your scanner under DCU...

Compressor is not likely bad because it was previously disabled by it's module. It did not overheat, there's a protection for that.

As long as the control logic is not satisfied, it's not energizing the compressor.

Let's finish the sensor you replaced. You say voltage looks low, it does look odd. This may totally still be an issue.
Compare it with other rear side numbers...
Also what height is the controller computing for new sensor?

Ultrakla$$ic

Thanks Cali for the response! If you notice the "SIGNAL 1 OF COMPONENT B22/3(REAR AXLE LEVEL SENSOR) is at 0.49 V. This is the value it was even before I changed the sensor. Again, when I move the rear up or down to see if the voltage is going to change it does not change. Some videos I've watched say that the system may be stuck in "LEVEL CALIBRATION MODE"...whatever that is. I just can't get the compressor to kick on AT ALL which is extremely baffling to me.

I have the positive and negative battery terminals disconnected to discharge all night and I'll reconnect in the morning but I can't imagine this system being this complicated..........sheesh. Alot of the internet says the relays can go out without warning but when I move the back wheels up and down the FRONT voltages change, but not the back......uuuggggghhhhhh And this NEW rear level sensor is from FCP Euro so I'm hoping its not bad.

What if I have a bad REAR DAMPENING component on my rear struts??? The air strut itself should only receive and discharge air but the dampening system is electrical and if it's bad maybe thats the reason the rear voltage arent changing???????

Ultrakla$$ic

Pic of the rear strut with the dampening module....

Ultrakla$$ic

Same as before because the rear will not raise

CaliBenzDriver

your answer lays within the Mercedes-Benz documents Master Surya researched for you.


hand picked precious documents

your issue is the module that misrepresenting your rear sensor.... follow sensor diagram to where it gets lost. Check voltages at module and sensor.

Leave your compressor alone for now.
Focus on what's wrong with your own car to make progress.

A lot of ppl have a "bad compressor".... but it is not your issue today.

You do have a good module, so now choices will be: either swamped module or bad harness or ....

CaliBenzDriver

DID YOU RETRAIN NEW SENSOR VALUE ?
Use scanner menu.

Arrie

Your rear vehicle level shows 127 mm. Your compressor will not try to raise the rear because Airmatic thinks it is way high now, over the limits in my opinion.

Your fronts are well in minus level so for that the compressor should come on.

Disconnect the linkage to the sensor and move the sensor arm for the whole travel and see if the level value changes. What I'm after with this is to see if the sensor is in position that is over range for the system, and it shows the same voltage until it is brought back to range. Could the sensor arm have jumped on "wrong" side of the travel "circle" and it won't show other than 0.49V until you bring the arm position back to the right area.

Ultrakla$$ic

WINNER WINNER CHICKEN DINNER!!!!!!!!!!!!!!!1

First I wanna thank EVERYBODY that have helped me and I mean that from the bottom of my heart! You guys are amazing!!!!!

So I got up this morning, hooked the battery + and -- terminals back on after letting the system discharge over night. Had the wife sit in the car with the doors and hood closed and start the car. Well, the compressor kicked on (THANK YOU CALI for keeping me focused because I was about to fire the parts cannon....LOL) so I then knew the compressor and relay were eliminated as a possible issue. The front raised, but the back did not. So I got to thinking, if the rear level sensor arm is DOWN then the ADS thinks thats where the car needs to be and thats where its gonna stay. What happened was when I took the old one off, I took a mental note of where the arm was and put the new one on the same way therefore replicating a defunct sensor. I think what happened is when I lowered the car, somehow the rear sensor arm either got in a bind and "broke" therefore falling in the downward position.








sooooooooooooooooooooooo I crawled back under the car for the 94u5098094092i5094 time and removed the lowering link and moved the sensor arm UPWARDS,











hooked it all back up and put the car back on the ground and checked for codes









No codes but the car was not raising................THEN ALL OF A SUDDEN I looked and the car was perfectly level!!



MY BABY IS BACK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

Needless to say it's been a very mentally frustrating week as I've learned more about the Mercedes brand than I wanted to...

Again guys, thanks to ALLLLLLLLLLLLLLLLLLLLLL OF YOU that have contributed. I seriously, dead serious, couldn't have done it without you guys!!!!!!!!! Strangly enough, when I first got this car I rememer reading a thread where a guy had this same issue on the FRONT of his car where the level sensor arm was attached in the wrong position and wouldnt allow the car to raise....................oh well, lesson learned.

CaliBenzDriver

Daren you did it! Now you can enjoy a great ride again. We're glad we could help you resolve this.


It's often an overlooked detail messing things up. You can make your car huge the road much better with a $20Ea.

rubbery stab links.... chewing gum!

The suspension airbags act as smart springs but all other regular suspension components are still there and requiring scheduled parts.

restores solid front toe destroyed by speed-bumps



Left part is the bad REAR (Right is good front)

Replace front lower control arms and all 4x stablinks specifically the cheap rear ones that make the chassis super unstable. It basically acts as if rear stabilizer spring was missing. With a good rear link the stabilizer can stabilize chassis.

> This cheap under sized link is responsible for overworking all other suspension parts. Replace it to prevent comprehensive wear with poor handling.

The front link is build well to go the distance with somewhat strong ball joints unlike rear soft rubber.

CaliBenzDriver

remove white sealant beed....

Can you do a surgery on your old sensor with a utility knife??
​​​​​​That would be to remove the white sealant to expose the inside electronic circuit.


I'd like to see if this sensor uses unsoldered pins such as headlight modules ???


Headlight control module


nearly good connections...

Ultrakla$$ic

Will do Cali!!! I desperately need to change my rear air struts (both) as the protective curtains around each has totally disintegrated!

I'll do this with a scalpel as this would be like going to work for me stay tuned my friend and thanks again for keeping me focused!

Arrie

Often times when it seems the whole thing is totally wasted the problem lies with the most basic detail.

One thing with the electronic sensors is that when it reads constantly the same value it probably is over range and won’t change until brought back to range.

Happy driving…again!!!

S-Prihadi

....................For Ultra.........

Ultrakla$$ic

Once again, thank you soooooooooooooooooo much guys. I seriously could NOT have done this without you guys. allllllllllllllllllllll of you!!!!