Do both doors not lock?
Trunk doesn't open
I think the mechanical sound your hearing is the central locking (PSE) pump in the trunk. The car actually thinks it's locking but the locks aren't getting any vacuum to lock. I have seen the PSE pump internally develop a leak. You should pop the trunk open, lift the floor up where the spare tire is, and feel the pump to see if it actuates. It is encased in foam on the bottom left side underneath the convertible hydraulic pump
It has keyless go.
Pop the metal key blade out of the remote, and use the metal blade to open the trunk
Nope sound is definetly coming from the door.
There is a key tumbler next to the trunk lid handle, turn it counter clockwise.
Get to the battery in the trunk and disconnect the battery for a minute.
It will reset the pump
The pump is the computer and vacuum/pressure motor for the locking system
I'll try but the sound is definitly coming from the door.
Right, but do this first.
I believe the sound is coming from the door because there is no vacuum present to move the lock. The electric portion is opening the valve in the lock by the door, but it can't because of the lack of vacuum.
ok that makes sense.
Removed the aux power for about 2 min. and reconnected. no dice.
The first sign of a problem was at lunch when I unlocked driver door by grabbing handle and passenger didn't open.
That is passenger side didn't unlock too.
How can I get that vacuum is not there?
If you reset the pse pum by disconnecting the battery, it should start working again hopefully
Sorry, do you hear the pump run at all when you try to lock the doors?
I started this mode, I was having trouble in the other mode. Can you try and lock the door with the remote while standing next to the trunk, do you hear the pump run at all?
Mercedes doesn't make the motor, but there is a wonderful thread that shows where to get a new motor, you just have to do a slight modification. Also don't forget to click accept if you found my answers helpful. http://www.benzworld.org/forums/w140-s-class/1585361-diy-pse-pump-post-mortem-resurrection-2.html
Are you sure you cant return it?
That is unusual since most times when the trunk latch leaks, the lumbar is out as well. They might have changed it starting in your year though, where they might have separated the circuits. I think both seats would be on the same circuit but I would still check it for leaks. The way I check it without pulling the seat out, is to start the car then shut it off and listen very carefully by the front bottom of the seats. Make sure it is whisper quiet where you have the car parked, such as your garage. If you hear the air leak, the I would pull up the seat and I would repair the line with some rubber vacuum line.