Working on an older e36 BMW, I can connect to the airbag system and even monitor seatbelt sensors as well as passenger occupancy sensor but will not pull up any codes(the light is on) or successfully clear codes.
I'm not familiar with the DS708. But With the Maxisys, to read or reset the air bag codes on some BMW's you need to use the BMW round adapter to OBD II. The round diagnostic connector is located in the engine compartment.
Correct, from the obd2 port inside the cab you can only connect to the ecm. This is happening from the 20pin in the engine bay. It connects to the airbag system but won't show any codes.