1993 190E 2.6 M103 engine

I have a sensor between the air cleaner box and valve cover on the driver's side, looks like a blue two-connector. Which is this? Also, where would the green 3-prong engine temp sensor be located? I need to stop the aux fans from spinning on high intermittently, and have been advised these may be culprits. Any advice on using a voltmeter to troubleshoot these? I'd rather see if they are bad before replacing them. I have a voltmeter, but wouldn't know what to set the selector to or what values to consider when testing these sensors. Thanks

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)