So, I am trying to save an 06 LR3 that came to me with air suspension troubles. I have worked on many Mercedes-Benz cars with air suspension, but I am having trouble getting this one sorted out. It was down on all four corners when I got it, and I believe that it has been sitting this way for a few months. I ran codes and got communication errors with VDC, air suspension module, instrument cluster, and more. Also a code that I am used to from Mercedes-Benz, “Pressure increases too slowly when filling reservoir”. This almost always means that the compressor is done. It was noisy too, and I have a parts vehicle with a bad engine so I went after it’s pump. I found that while my new one had it’s original Hitachi pump, the donor has the updated AMK unit dated from 2013. I verified on the bench that it works, and installed it with all of it’s updated mounts, hoses, relay and connections. Once in, i cleared faults and tried to fill the system. But the pump will not turn on. It operates with direct power, but the car will not do it. I do now have a permanent fault for no communication with suspension control module, and the code for invalid data from vehicle dynamics control module keeps coming back. Also, when I activate the pump with direct power I can fill the front struts, but the rears do not fill. I was able to get the rears up one time by lifting it on a rack and setting it back down, but that only worked once. On the third try, the front went up, and then the supply hose fitting popped right out of the pump. Good thing that I have another one.
I am going to replace the pump again, and the front/back valve block too. But I expect that I will still not be able to get the pump to activate. Does anyone have any more ideas that would push me in the right direction? Any insight would be appreciated.

Technically you need to update the software to AMK version, but I’ve heard they will still work.

did you swap the relay out?

I had a heck of a time with my system. Faults and communication issues. Turned out I had put the fuse in the wrong slot after disabling it to see which end sagged. Check the fuse carefully before your other steps. You can search through my posts if you want to see the specific error messages.

When I jumpered the relay, the pump would run as an FYI...

Well, all fuses checked and rechecked, good advice but they were in the right places. After replacing the front/rear valve block, we get all four corners filled with air, but only by putting direct power to the pump. Still getting VDC communication codes. I replaced the switch group for air suspension and special programs, no change. I guess that it’s time to start tracing wire continuity, which I was avoiding. It’s not my favorite game.

Do you have a diagnostic tool that allows you to activate portions of the EAS?

Autologic allows you to open valve blocks and run the compressor.

point being if it can actuate these items the vehicle should as well, so wiring could be ruled out.