electrical nightmare is finally over. It is my '91 535i. Symptoms- Collectively intermittant power windows,sunroof,locks. Wipers only work on high. Interior lights don't come on when doors open. They work when switch is in other postion only. All intermittant, but fail a lot more than they work. Changed the fuseable link and all fuses under rear seat, apply Stabilant 22a to the connections and reassemble. No change. Changed the Relay Module with a good donor. No Change. Disconnect neg cable on battery, pull both Relay and General Modules, the 2 orange relays, and the 1 gray relay. The orange and gray relays have a tarnished/burned brass appearance on the spade connectors. No sign of electrical arcing, just discolored and look kind of burned. I clean them like a shiny nickel. Next. Apply Stabilant 22a liberally to all module pins and their sockets as well as the 3 relays and their sockets using a modeling paint brush and reinstall. Next, unbolted the 2 ground straps that attach to the driveshaft tunnel, shine-up the eyelet connectors on the straps and all hardware, apply Stabilant and re-assemble.
Reconnect the battery and so far, the past 8 hours of testing have been perfect. By now, it should have failed for sure. The next few days will tell the tale, but I think I'm done here. Javier and Bill R. , thanks again for the great suggestions that brought me to this point. Ryan, you have the same symptoms, so hope this fixes you, too.

Keith in AZ.
'91 535i 193,400
'89 735il 243,500