Here's some answers. . . .
what systems are available on the 38pin Diag Connector
Check MENU #2 showing a picture of the 38-pin connector. In the table below all of the available systems are shown for your car.
Regarding a scanner vs computer+sw: The only real advantage is the portability and compactness of the hand-held scanner vs the laptop plus adapter and sw.
The code readout is somewhat different in the OBD than what you read from the 38 pin connector with a "Mercedes" only scanner such as AST's Retreiver scanner. But a DTC is a DTC!!
Regards . . . . JimF
'94 S500 Cpe
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