I got a 86 yota and my temp gauge goes straight to hot for some reason. The plug is plugged in by the tstat but what is the other wire that comes off the harness beside it.

heres a pic

 

Im following this thread cause my truck started doing this also.

 

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Your temp gauge sensor will be in the intake manifold between cyl's 2-3. You will have to look straight down to see it.

As for the sensors in your picture it would be helpful to know some information about your truck. IE what engine,ac,tow package,tranny etc...