I have a 2008 CLS550 - it DOES NOT have the auto start and the keys only unlock/lock the doors, and pop the trunk. I have replaced the batteries 2 times and checked the battery's with a meter and still I cant use it to unlock or pop the trunk. I have pulled out the inside of it and checked for water damage or anything loose and it looks good. I have also "married" the keys with the car by turning it to the on position without starting the car for at least 30 min. I have read everything online to figure out the problem. Does anyone have suggestions?

 

Have someone pull fault codes for definitive diagnose. If steadfast on replacing parts without fault codes first thing to check would be antenna amplifier located in left c-pillar – part # 2198200689.

http://workshop-manuals.com/mercedes...29/page_15401/
https://www.google.com/url?sa=t&rct=...,d.cGc&cad=rja
http://workshop-manuals.com/mercedes...on/page_16466/

 

Both times I change the batteries out was at the dealership and I think both times they gave me bad batteries probably trying to get me to buy a new key. I went to CVS bought the batteries and they were good put them in and it worked fine.

 

What dealership?

 

Park Place Mercedes in Grapevine, TX