Yamaha - Thermo Switch Assembly Engine Temperature Monitoring 6H4-82560-00-00. Overview. Overheating issues aren't something you want to guess about, and this switch is one of the key pieces that keeps you informed. I've seen motors run fine mechanically but still throw warnings because the thermo switch wasn't reading right. It's a small part, but it plays a big role in protecting your engine when temps start to climb. When it's working correctly, you've got peace of mind every time you're runn