hi everyone ....i am new to the forum. i have never had a mercedes benz before and recently aquired a 2000 S500. i have had the vehicle for the past 3 months and everything worked great, but as of 3 weeks ago the rear air assist suspension stopped working . does anyone know what usually causes the rear air suspension to stop working?? i know it can a number of things, but is there one thing that is the most frequent that causes this?? if anyone out there knows......ALL SUGGESTIONS WELCOME!!!!!!!!!!

 

Hi,
You need to be more specific. What does "stopped working" mean.

Is the whole car on the bump stops? Just one (rear) corner? You have a dash warning but everything seems fine?

Since you refer to just the rear it is possible that one of the height sensors on the Airmatic has broken and is no longer sensing vehicle height. These sensors use "flimsy" looking plastic arms (like on a building crane) to connect the suspension strut to the sensor potentiometer. If you remove a wheel you should be able to see these quite clearly about 2/3 the way up the strut.

Of course there are many other potential causes of the system not working correctly. Connector water ingress, CAN problems but the usual problem is an air leak / pump failure.

Does the air suspension pump still work (tried the fuses?). You should be able to hear it running quite clearly if the car is low. It is sited under the RH front wheel arch behind the horizontal ventilation duct in the wheel arch liner. This usually causes the whole vehicle to be low. there is also a valve block which distributes the presuured air to the appropriate corner of the car. This is controlled electronically so many issues including mechanical could cause a malfunction.

Define the problem a little more fully and I will see if I can add anything further.

A air leak at the top of the strut is bad news. a new strut is very expensive so correct diagnosis is VERY important. If it is an air leak a lower cost repair to the strut top mounting is available from some aftersales outlets in the USA. search this forum to find details.

Good luck.

stuart

 

thank you very much for your reply......
im sorry i should've been more specific. yes the rear of the car is on the bump stops. the display on the dash does not tell me to stop my vehicle and take in for service or any message like that. it just displays "airmatic....vehicle rising". i took a look at all the fuses this weekend.....took them all out and tested them, all fuses good. when i placed them back the car lifted. i drove it around and it still displayed "airmatic....vehicle rising" but never layed out again. the next morning the car wouldnt lift again.

 

Is the pump running whilst vehicle rising displays??

 

I actually have the same problem on my 2002 s500, but my front cans are cracked on the top, so my front sits really low and my back is really hight for some reason, dont even know why, my display says, car is too low, stop the vehicle.

 

Gixxer.

I have posted several posts on this topic if you use search.

Basically it is likely YOUR car has a leak so the pump has to work VERY hard to keep up and maintain the required height (make good overnight losses). This will lead to pump failure since the pump is intermittent rated. I guess you also get ABS, EPS warnings until the car manages to get to the correct ride height.

It is possible that you have a broken height sensor but in my (limited) experience your problem will be the leak at the strut tops (or possibly elsewhere)

Struts are MEGA expensive and if the car has covered high mileage (lets say 100k+) the units should be changed in pairs = MEGA X 2 expensive!!

However I understand a repair kit is available (posts exist that state from where) but I have no experience to share regarding how effective etc these are.

Stuart.

 

i dont hear the pump running but the car does lift. another question....does the car rise while your driving or does it only rise when the vehicle is still??

 

There is a switch on the dash which when illuminated RAISES the car (need Ignition ON).
If you operate this switch you should hear the pump running. You will also likely get a "Car Rising" warning on the dash.

The car goes up and down on its own whilst you are driving and is determined by speed and vehicle attitude.
The system also senses how the car is loaded. If you have a full load air will be required to rebalance the car to the ideal ride height. This process starts as soon as the ignition is turned on/engine started.

i suspect you have a damaged rear end height sensorso although the system tries to adjust the ride height it is unable to sense to change. Alternatively you have a leak and the pump can't make good the loss of air.

I suggest you get the car to a dealer and request a diagnosis only. Agree a price for this before you start. The easiest way to find out what is wrong is to get the diagnostic codes read. (Not the same as getting the engine codes read. needs special equipment)

stuart

 

ok i think i figured out the problem i believe its the pump.......
is the pump suppose to make a load noise or should be quiet?? this is what happens....i turn the car on and after 5-10 minutes i here the pump (really loud). the pump stays on for like 1-2 minutes tops then turns off. the car at that time lifts a little then the car can stay on and wont lift anymore. so i have had to turn the car on so it can lift then turn off, then back on so it can "reset" and start the pump over and get a little bit more lift. once the car has lifted it does not go down till the next morning when i turn the car on, other than that its stays lifted up.....its like once the car has been parked for more than 8 hours it will hold the air but when i start the car it releases all the air then i have to go through the whole process of turning the ar on and off.

***i hope it makes sense!!!! thanks!!!!

 

Pump is working (at least to some extent) because it lifts the car.
Pump noise is noticeable from inside the car. Not sure how to use terms like LOUD. Its not quiet but it should not be real loud either.
Wasn't aware that the pump had a thermal/time cut out on it but it would appear that it does. The longer you continue with your routine the more likely the pump is going to totally fail. Pump costs circa 500USD (educated guess). Easy to fit DIY if you know anything about general car maintenance.

All Airmatic cars drop overnight / after standing for a period. Some more quickly than others. After a holiday/business trip etc you will find the car completely down and this does take about a minute to get the car to correct height.

If the pump manages to pump the car up too high something else is wrong. Have you checked the height sensor arm as I suggested. Is the "Wade" switch ON on the dash (two red LEDs? It shouldn't be.

Easiest way forward is to get the car scanned for DTC Diagnostic Codes at a MB garage or one with appropriate equipment to access the appropriate ECU.

Good Luck.

Stuart