On-Board Diagnostics [OBD] is a motor vehicle bus used to monitor engine functions. OBD II is the second generation of that interface. The graphic below details a 20-pin male BMW connector to female OBDII connector Cable assembly
BMW to female OBDII Cable assembly
As a manufacturer the company producing the car can use any type of connector that may be required. They could than require a special purpose adapter or a generic one to interface with the on-board connector.
Additional OBDII cable assemblies;
OBDII to DB15 pin Cable
Female OBDII to 2x2 pin Cable [VW]
Right Angle Male OBDII to DB-9pin Cable
Male OBDII to DB9-pin Cable right angle
Male OBDII to Male DB9-pin Cable
Male OBDII to Male DB15-pin Cable
Male OBDII to Female OBDII Cable
20-pin BMW to OBDII Female connector
Ground pins; 4, 5 to 19
K Line pins; 7 to 17, 20
L Line pins; 15
Power pins; 14, 16