2007 GL 450 air suspension compressor mystery
 

Just got the dreaded Visit Workshop dashboard message. Both front ends are down and I don’t hear the compressor working. The message appeared suddenly while driving and the front lowered gradually “within 4 hours”. The rear is lowered too but not all the way down.


I replaced the relay and the fuse but no go. I bought the Arnett compressor and wanted to see if my compressor is dead, so I removed the old OEM compressor and decided to plug both power cables, without installing the air hoses. I wanted to try if the compressor will work before I attach the air hoses. I started the car for 10 seconds, turned it off. Nothing! I did not hear the air compressor working at all.


What else could it be? Could it be something else? How to properly test my old compressor to determine if it’s faulty? What else can I do? I tried two different relays and the correct fuse. What else can I try?

I also have a 2007 GL450. I just replaced the air compressor and front struts from Arnott this weekend. I've had the car since new and replaced OEM with Arnott air compressor and front struts about 5 yrs ago. So this is the 3rd air compressor and set of front struts on my GL (OEM, Arnott's 5 yrs ago, and now this new set). Interestingly, I got a new relay included with this Arnott air compressor. I didn't get a new relay with the last Arnott compressor.

The first thing I would do is make sure you are getting 12V power to the power connector. To do this, you need to unplug the power connector, start the car, press the raise car height button (this will ensure power signal is sent to the compressor) and then test the connector prongs within the connector. I realize you've replaced the fuse and relay, but this will at least let you know that power is being delivered to the compressor.

If you get 12V power to the connector, then you know relay and fuse are working properly - then there is a problem with the compressor. If you don't get 12V power, then you need to replace either the fuse or relay. Btw, when I got my new Arnott compressor, it came with a new relay and specifically said to NOT use the OEM relay, but to use the new one that came with the new air compressor. Did you get/use the new relay supplied with your Arnott air compressor?

your airmatic module might have disabled the compressor due to permanent failure. the module needs to be accessed and interrogated via star/ das to re-enable functionality

I also got a new relay with the Arnott air compressor and I tried it but no air compressor activity. As for my car, I replaced the rear air bags 2 years ago as they were leaking miserably. I used the Arnott brand and it was very easy installation. I would never dream of doing the front struts, seems a mission impossible to me. kudos on getting that done.

During all my testing of the air compressor, I missed the step to press raise car height button, never thought of that. I thought the car will command the air compressor to work since the front struts are sagging all the way down. I will give that a try. Just afraid that aix is right and I need to reset the airmatic module via a star diagnostic tool. I will also check the power coming from the wiring and see what’s going on there.

I guess it is time for round II

By the way, Arnott offers lifetime replacement for their parts. If you still have the old ones that you installed 5 years ago, send them in to be replaced.

Seems like it :(

I have FOXWELL NT510 MB Scanner, would that do the trick?



There is a question in the amazon listing by one of the customers:



Will the tool fully diagnose air suspension issues on a 2006 CLS 500?

A: Thanks for your inquiry. I am glad to inform you that FOXWELL NT510 with Benz software will help you diagnose air suspension issues on 2006 CLS 500. Please buy with confidence.

If you have further question, please feel free to contact us, we will be more than happy to assist you at the earlist.

Have you and your family a wonderful day!

Best regards

Obdzon service before sales team

Just an update that I jumped the old "supposedly defective" air compressor using a 12v car battery and it worked!

Back to square one !.

I need the weather to get better and will lay beneath the car to do further examination. I feel sorry for the time and effort wasted in taking the air compressor out.

Seems quite likely at this point that the computer has disabled the compressor. You just need to reset it. Go dig in to your Benz-specific options on the tool and see if there is a "reset Airmatic" option.

If you don't have that option, you need a tool that is MB-specific. I'll go look on my MBII for it, if you go through and like 100 of my posts.

Otherwise you'll need a Star/DAS system, and they (1) ain't cheap, and (2) are tricky.

Your post makes sense so I liked it. Sorry, you will only get one like, unless you can post 100 useful posts here, then I will like them.

I'll look around and see if I can get Autel DS708 or something similar and will go from there.

lol I am the god of likeable posts. Not really; there are friendlier guys, and alx is way more useful, but I'm trying.

I think you missed a key point. The ECU tools work on three different levels:
1) OBD2 error codes and basic OBD data reader and code resetter
2) Deeper data like oxy sensor voltages; mostly emission related stuff. This still falls under the category of OBD2.
3) Manufacturer-specific (e.g MB) functions (e.g. Airmatic). iCarSoft / MBII are examples. I think there are others.

4) God tier (Star/DAS)

I don't know about Autel; check to see if the tool performs at #3 level before plunking down cash. Autel is super expensive because it spans a range of vehicles; icarsoft specializes in Benz.

Mercedes Medic has a writeup on the scan tools.

Get a little bluetooth module to do #1.