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Super mechanic
Super mechanic, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 16844
Experience:  ASE Master, 30+ years exp. troubleshooting, diag. electrical, collision
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2001 S500 came in with the rear suspension too high. As soon

Customer Question

2001 S500 came in with the rear suspension too high. As soon as we lifted the car we could hear air leaking from the front struts. The left front strut was leaking air and oil-so we installed a new strut from Mercedes. The right front strut was only leaking at the strut top-so we installed the update kit from Mercedes. So now we have no air leaks. Here is where the problem is I can raise the car with my scan tool-Launch-; yet when I try to lower it neither the front or rear will lower. I then released the air from all 4 struts at the compressor and the car lowered. I then was able to actuate each strut with my scanner and raise each strut individually. Yet I still can not lower it. I suspect pressure relief valve in the compressor. It is receiving the 12v yet I am not sure if is receiving enough of a ground. Basically need help determining if I have a control problem or a pressure release valve problem.
Submitted: 6 years ago.
Category: Mercedes
Expert:  Super mechanic replied 6 years ago.

Hello and welcome to Just, Super mechanic here. About your vehicle.



There has been a service bulletin for that type of concern. Here is what it states.


Suspension - Will Not Lower/Visit Workshop Message

Date: March 31, 2009

Order No.: P-B-32.22/77


Group: 32

All Model 220 Vehicles, VIN Range A196614 up to A271200


Except Vehicles Equipped with Active Body Control (ABC) (code 487a)

Vehicle Does Not Lower and/or "Airmatic Visit Workshop" Displayed in Instrument Cluster

If you receive customer reports in the above model vehicles of the Airmatic suspension not lowering and/or "Airmatic Visit Workshop" displayed within the instrument cluster, perform the following.

1. Remove right front underbody paneling








2. Unplug electrical connector from pressure relief valve (Figure 1, arrow).

3. Replace pressure relief valve. Carefully pull out the valve; the pressure piston is pressed out by a spring. It is important to observe the installation direction. To check whether the pressure relief valve is installed correctly, it must be possible to push the pressure piston down flush with the edge of the housing against the pressure of the spring.

4. Reassemble vehicle

5. Verify that the vehicle level rises and lowers.

This condition is the result of the pressure relief valve (A9/1y1) not opening. The fault code C1517-032 [Correction times when emptying or filling are too long] may be stored.






Customer: replied 6 years ago.
I too found that service bulletin. I was planning on Monday to check the valve. Do you know what type of ground signal the valve should receive? I really don't want to guess wrong if at all possible. Also I will try supplying my own ground signal on Monday and see if I can activate the valve manually. I'll touch base with you eithr Monday or Tuesday. Thanks for the help.
Expert:  Super mechanic replied 6 years ago.
There is not alot of info available on the control of it, however, it would need to get a ground signal to activate the valve. Let me know how you do on Monday, or Tuesday, thanks.
Customer: replied 6 years ago.
Update I can manually operate the air release valve by supplying a ground to it. So unfortunately the service bulletin you supplied does not apply. At this point i'm doing a pin out check on the air suspension control module. It looks at those I may have a bad air suspension module. I'll keep you updated. It will take 5 days or so if I need to purchase a module. Going to give the customer the choice between used and new-very expensive.
Thanks again
Expert:  Super mechanic replied 6 years ago.
Okay, best of luck with it.