Found this at R3v:Sorry for the format, this is from a huge excel spreadsheet I've been compiling of c101 pinouts
Columns are as follows
Pin #-size wire-Color(chassis side)-Size-Color(engine side)-description
91 318is
Pin # Size Color Size Color Description
1 Small Blue Small Blue Battery Light
2
3 Not Used
4 Small Brown/Violet Small Brown/Violet Coolant temp sender
5 Small Black/Brown Small Brown/Green Oil Pressure Warning
6 Large Green/Yellow Small Green/Yellow Fuse 9/pin 16 diagnostic Connector
7 Large Green Large Green Start Input
8 Small Yellow/White Small White Fuel Rate output
9 Small Black Small Black Engine Speed
10
11 Small White/Blue Small White/Blue SI reset input
12 Small Brown/Black Small Brown Check engine light
13 Large Violet/Red Large Green/Violet Fuel pump relay pin 87
14 Small Blue/Yellow Small Black/White Speed Output/Input to ECU
15 Small Black/Green Small Black/Green Pin 85 Unloader Relay
16 Small White/Black Small White/Black SRS Diagnostic Connector
17 Not Used
18 Large Black/Yellow Large Black/Yellow Starter
19 Not Used
20 Small Red/Yellow Small Red/Yellow Power ABS unit
Likely the pinout is identical for most of the post-88 e30s. The pre-88 e30s have slightly different wiring, especially that #20 ABS pin.