plug/wire designations

[highperboi]

I dont understand how the wires are disignated A4 D8 and so on on the ecu plugs... can anyone explain to me how this works?

 

[posol]

here's a lame ascii art....
some cars have a B, some don't etc... this is just an example.
obd0 and 2 are differen't.... but since i see a 5th gen coupe, here's what a basic obd1 ecu looks like. the letters are just examples... i'm too lazy too look up and verify that there is no B plug...

|---------------------------------------------|
| A1 A3 ... | c1 c3 ... | D1 D3 D5 ... | 
| A2 A4 ... | c2 c4 ... | D2 D4 D6 ... |
|---------------------------------------------|

now remeber, some obd's don't have a C plug and all that... but basically, it goes left to right abcd...
and goes numbers like i did above.

obd2 is different. they have 3 or 4 rows sometimes