For my 2005 ES330, I wanted to disable the rain sensing functionality because it did not work. Variable intermittent wiper functionality is what I wanted. I had read in this thread and in another that simply unplugging the 4 pole wiring connector at the sensor was sufficient to have the system revert to variable intermittent wipers. This is not the case, at least not for my 2005 ES330.
However, it is possible to revert to intermittent functionality by removing the sensor lens from the sensor assembly. Once one has popped the sensor and its cover off the windshield, the lens can be accessed. It can be easily removed by pushing outwards on two plastic tabs that hold it in. Once the lens is removed from the assembly, reinstall the remaining sensor assembly with cover. Then make sure to plug in the P4 wiring connector. Now the wipers revert to variable intermittent wipers. At the '+' setting, the wipers will wipe every 2 seconds. At the '-' setting, the wipers operate every 10 seconds or so. The intermediate settings are 3 and 5 seconds IIRC.
