There's one update regarding diode position that could be added to your excellent summary document. This update is captured in the D3 EBC thread so is easy to miss.
The diode needs to be upstream (CJB side) of the splice so that the TowPro manual override button illuminates the trailer brake lights. The sketch below is for D3 wire colour but the diode positioning is correct (just change green/purple to red for D4).
https://www.aulro.com/afvb/images/im...015/12/445.jpg
See also page 2 of the D3 thread at this link:
http://www.aulro.com/afvb/d3-d4-rrs/...d-photo-2.html
I'd update the D4 wiring diagram on your last page but don't know how to revise a pdf file.
Regards,
Scott

