I am having an electrical issue that I can't figure out. My lights and wipers will randomly stop working. I can leave the negative cable off for a while and they will work but then they may go out when I'm driving but definitely won't work on the next start up.
There were a few pins corroded in the BCM, I cleaned those up and it had no effect. I saw in an FSM where if those fail the IPDM test to check the ground for that circuit but I am not sure where that ground point is at. It is only those 2 things that do this, everything else

 

It's never good if the BCM has gotten wet but hopefully that's not the source of your problems. Because if it was, one would expect many other things to be going wrong. The IPDM houses relays for the wipers and headlights and also does some "processing" with regard to when to cut those relays in and out. Is your IPDM dry? None of our black boxes are tolerant of water intrusion.

I don't know what year of model you've got but on my '13 sedan those two systems DO appear to share ground points, "E22" and "E46". The harness illustration shows "E46" somewhere near the top of the firewall on the driver's side of the engine compartment. It shows "E22" on the opposite side near the IPDM. I have the feeling many systems use those two ground points so while they're certainly worth inspecting I'm not sure that will be your answer. Let us know what you find.