I pulled the heads today on my L98 and I discovered (what appears to be) another knock sensor screwed into the head. The sensor in the block was connected to the wiring harness, but this one was not attached to anything. What is the purpose of this "extra" knock sensor?

The right head should have a fan switch; and the left head should have the temp gauge sending unit. There's only one knock sensor.

Thanks, RB83L69. I forgot about the fan switch.