DIY: Making an ENET OBD2 cable to hook your BMW to a laptop
1st Step: 2nd Step : Remove the outer plastic layer of the ethernet cable and expose the internal wires. It will be like the image shown below You need to identify which color cable is from which pin number, this is very important. You will then have to tin the edges of the cable using the soldering iron. Pin 4,5 and 7 of Ethernet cable will not be needed in this DIY so you can cut out the Blue, White / Blue and White / Brown wires. 3rd Step : Open up the OBD2 Connector. You will see 16 pins, 8...
Source: team-bhp.com