I have found a manual the has 28 pages that talk only about the test points and functions on the u200 and e36 boards.
The individual pins on the connectors are discussed one by one in the trouble shooting section.
The earlier service manauls did not have this info, but the later manual written for a later truck, has to be used with a pinch of salt. Essentially the design has stayed the same but there were efforts to improve from one generation of truck to another