Hi, could somebody tell me what this is please? Seems to be a glass window in it. Is this to show if it has fuel going to the injectors or something? X300 4.0L, 1996

 

This is the cam position sensor. It helps the ECU identify cylinder #1 when the engine is starting, among other things. Not sure what purpose the little window serves other than perhaps identifying when cylinder #1 is at TDC (this is just a guess on my part).

 

Ok. Thank you.