built the DIY tester. works like a champ. for posterity, I used the pins from a 9-pin d-sub conector and they fit like a glove.

anywho.....Holy Stuttgart Batman!

here is the breakdown of the codes that I pulled off my 1995 E420:

OEM LED connector - 6

Pin
4 - 1
6 - 13, 25, 26
7 - 2, 5, 11
8 - 6, 7
16 - 1
17 - 1
19 - 6