For a diagnose of a BMW the 20-pin round jack is necessary as used from 1996 on or the 16-pin OBDII multipoint connector as you an see under OBD Techniques / Plugs. It has to be considered, that pin 20 or pin 17 is needed for diagnostics.
The very old jacks (15 pin etc.) as shown under OBD Techniques / Tips and Tricks are not suitable for diagnostics.
