2011 gl450 airmatic

  mercedes/gl-class/2007-2012

changed mechanical rear shocks did not touch anything electrical at all. set the car on the ground with the lift holding up enough to fill the suspension without load but the car now just says malfunction airmatic and wont activate the compressor. my snap-on scan tool gets in for about 2 seconds then i lose communication with the airmatic  module. all powers are present at the module but my CAN high is matching my CAN low signal.  car had a rear SAM problem prior to repair but nothing else is having problems and there is a code 5557 in the abs module present. the system seems to be logic locked or something is draining down the can. i disconnected the CAN plug from my airmatic unit and the numbers are still off in regards to CANBUS high . is there any way to test without throwing parts at the car ?

8