Having issues over here.
I have a 2007 GL450 and the Airmatic suspension has not been working for some time... its been parked in the garage and the battery is dead. In the past ive been able to jump start it, but not anymore. So, I replaced the battery last week and the key will turn on the electronics for the car, but it wont crank whatsoever.
Since there is power, I hoped hooking a scanner up to it would tell me, or if I needed to reset the computer after battery replacement. Scanner powers up but it wont communicate with the vehicle. I tried a couple different scanners, but neither will communicate.
I have checked the front gateway and it is dry and clean.
I checked the rear SAM unit, its dry and clean.
When I pulled the battery out, I unhooked the auxiliary battery as well, was this a mistake?
Im wondering if the computer lost the key FOB information and now wont crank.
ANY clues are welcome.

 

The key info is written to non-volatile RAM. It won’t get lost or erased unless a nuclear bomb causes an EMP. If the info could be lost by having a dead battery MBs would be dead all over.

 

I pulled both batteries before to replace and didnt have an issue starting.

 

You should be A-ok after you installed two new batteries.

The fact even scanners no longer communicate says something about CAN-D.

Let me ask you to pls measure your AUX voltage... super low, right?

Know that a dead MAIN causes a dead AUX.

You need to use a CTEK float charger maintain battery voltage while parked. If Main is not drained then AUX will remain full.

+++ BONUS FOR LATER ON...
Measure AUX after engine start :
Higher than 13Volts ?
> check blown fuses.