BMW 20-pin Diagnostic Socket Pin-Out Diagram

Handy pin-out diagram for the pre-OBD 20-pin round diagnostic connector on 80s and 90s BMWs from PinOutGuides.com [https://pinoutguide.com/CarElectronics/car_diag_pinout.shtml] 

 

1       Engine rotation speed [TD]
2       CAN-High     
3       CAN-Low
4       Shielding
7       Oil service and Inspection reset    
11     External starter turn on
12     Battery indicator
14     Battery power     +12V
15     ISO 9141-2 L Line     
16     Ignition +12V     
17     ISO 9141-2 K Line
18     Programming line [PGSP]
19     Ground [GND]     
20     ISO 9141-2 K Line [TXD]

 

https://pinoutguide.com/CarElectronics/car_diag_pinout.shtml