Data Link Connector: Description and Operation

The BMW service tester communicates with the DME control unit through the diagnostic Link. This two-wire link is used only for diagnosis purposes and has no function during normal vehicle operation. The service tester and DME control unit communicate through digital signals. The DME control unit has a numerical "address" which differentiates it from other control units and systems on the vehicle. When the control unit is called, it replies to the service tester that it is functioning. The service tester communicates with the control unit through commands entered on the keyboard. The actual digital signals are controlled by the service tester's diagnostic program or software which is contained on a magnetic disk.