I cleaned all connections with LPS electric cleaner. That's all good. I marked the sensors and confirmed faulty or near faulty, swapping them into the left front. Which is easy to do, just turn the wheel, bend back the inner fender and jack up a bit. Clip in one sensor and let the mayhem begin! So it was easy to confirm good/bad.
The sensors that cause the "Wipe sensor" message don't actually throw a code, so they are hard to trace. And even when say one sensor trips a code, it can affect an adjacent channel.
So these youtube videos of guys replacing all 4 rears - not a bad idea at all.