Found out my Benz has the 38 pin connector under the hood and the 16 PIN ODBDII connector under the dash. I have have downloaded latest PC Version 6.31 as well as latest OBDII and all Benz updates.   Battery is charged, tested with the key in the last position before starting the engine.  According to the MD802 the 16 Pin under the dash is primary for engine, 38 pin under the hood is for additional systems.  Unit pulls my vin and performs some test, or I go under Mercedes and select until I get the 208.370 CLK 430. Under my saved scan shows ECU Data = ML Status Off, 0 codes found, Monitors N/A = 1, Monitors OK 9, Monitors INC 0, lots of saved data, modules present = Protocol  KWP 2000 ID $10,  Either way I choose my vehicle, go to scan, on the 38 Pin connector, watch it go through the testing each control unit I get the same error unable to communicate with module or the full system scan ends with no status. Never even saw anything to do with the SRS/ARS as far as a module. Really disappointed.  I looked long and hard before finally selecting the Autel Maxidiag Elite MD802 All Systems over the Launch CRP129 Auto Code Reader OBDII CRP-129 Creader Professional CRP 129 OBD2 Scanner. Anyone have any ideas?

 Thanks, will give it a shot.

 Thanks, Jason, it was an ebay this one was a molded assembled cable it was cheap, I did by the BMW adapter, still need to get the correct serial cable, I will also get an official Mercedes 38 pin connector/adapter. Thanks again.

 Tried it, deleted the most recent version of the BENZ, downloaded the previous version, tried Auto Scan form 38 PIN and 16 Pin = no Diagnosis, tried testing the individual modules still get the unable to communicate with modules. Using the 38 pin and the detect my vehicle, the scanner links and pulls up my VIN. I am so stumped....

 Still not getting anything from the North America tech support, One of them told me I might have bought an AUTEL MD802 with software for Chinese cars??? I searched online for hours, many blogs and could find nothing about a US update/US software. My Scanner shows English, if there was such a thing wouldn't the scanner by default show Chinese. Of course I know a lot of the scanners have multiple languages.  Feel like I am spinning my wheels..

 Getting zero support from autel. What has become clear is the autel md802 maxidiag elite ds all systems does not work well with mercedes. I have seen many posts similar with bmw. What it does do you can buy Bluetooth OBD12 device for less than $20. It may complete auto scan, it may communicate with some modules on some Mercedes and  BMW but you have to ask yourself are you willing to take a chance for $300 with a company that provides little to no tech support. At this point I have a next to useless $300 scanner. I have had a ticket opened with autel since the 17th, their only solution call our tech support in California, I called them long distance was on their all support is busy for 20 minutes, left a message and did get a call back from Rick who said he can't reference autel ticket info, his suspicion is I bought the autel scanner loaded with software for Chinese autos? And he will get back to me over a week. I have uploaded multiple screenshots of the unable to communicate with modules (all modules), the autoscan results no diagnosis (same 38 pin and 16 pin results). I have also got no technical support from autointhebox where I bought this device from. I guess the end result is I would not recommend buying an autel scanner or buying from autointhebox. I will update my blog if this changes, I really would like for the scanner to work as advertised and am willing to work with the seller or the manufacturer, to be positive instead of negative.  I would like to say one positive thing on the people that take the time to respond to these forums and provide information and that is thank you are the best people ther are. May the efforts you proved to help others come back to you as positive events in your lives.