FJCruiser Rain Sensor Fault

Whoa, that sounds like a bunch of things going wrong at once! I've got an FJCruiser too. The rain sensor controls the wipers and headlights, and also talks to the speedometer. Is your windshield original? I read somewhere about issues with the auto sensor and bubbles forming in the gel pad between the sensor and the windshield. Does that sound familiar?

Bubbles in the gel pad? That's new to me. Where exactly is this gel pad located? Is it easily visible, or would I need to disassemble something to inspect it?

Yeah, the gel pad sits directly between the rain sensor and the windshield glass. You might be able to see the bubbles if you look closely at the windshield where the sensor is mounted, from the outside. If you can't see anything obvious, I'd suggest a workshop visit. The sensor and gel pad are delicate so I wouldn't recommend disassembling things yourself. A damaged auto sensor can cause issues.

Thanks for the insight regarding the gel pad. I checked as you suggested and indeed there were bubbles. I visited my workshop and as suspected the gel pad was the culprit. Repair cost came to 62€. Thanks for helping me diagnose this malfunctioning sensor.