OBD2 pinout
 

Attachment 30340

1 Discretionary* (GMLAN SW CAN Line)
2 Serial data (class 2)
3 Discretionary* (GMLAN MS CAN H)
4 Chassis Ground
5 Signal Ground
6 Output/field service enable (if used)
7 K Line of ISO 9141-2
8 Keyless entry program input
9 Serial data (UART)
10 - line of SAE J1850
11 Discretionary* (GMLAN MS CAN L)
12 Discretionary*
13 Discretionary*
14 Discretionary* (GMLAN HS CAN L)
15 L line of ISO 9141-2
16 Un-switched Vehicle Battery Positive

* Discretionary means that the J1979 specification leaves this pin for use by the manufacturer.