I'm usually pretty good at finding the right wiring diagrams in rheingold, but this one baffles me somewhat. The key thing is a 10-pin connector on the driver side switch block (attaches to side of seat) - named
S153, and it shows that the lumbar control is done "via seat adjustment switch block", but in rheingold, it only shows 6 wires (none for the lumbar wires) in this switch block rather than the full 10 wires.
Still... i'll share what i found. Hopefully, others can chime in and add to it and complete the wiring picture you are looking for.
The OP's initial scription says he needs 11 wires total, but in his google pictures, he seems to indicate he only hooked up 2 wires into the 10-pin connector (where he shows original 10-pin connector and new one). Then in another pic showing his "harness", there appears to be 5 wires shown..
Here's an
enlarged version of the wiring diagram
Good luck - this looks like a fun project and a worthwhile retrofit!
