replaced transmission now check engine light

I have a 1997 Voyageur 3.0 3 spd ..I replaced the dead the code is 37 transmission temperature sensor low voltage. I am thinking
maybe I got fluid in it or something..but where is it.? I have never heard of this. Does anyone know where this thing is ?.. I'd appreciate the help as I don't want to wreck the tranny. thanx

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