The hottest fluid is the line from the converter to the cooler.
The cooler fluid is the return line.
Think turbo intercooler.
The trans sees the return line fluid temp - not the converter to cooler temp.
Very little fluid from the converter gets pumped directly in to the trans.
True. Oil returns to the trans from the cooler and is routed through the lube circuit in the rear of the trans, then falls to the sump along with oil being shed by internal components. Oil in the cooler lines has either been heated by the converter or cooled by the cooler. Oil in the sump has been returned from internal use and is being picked back up by the pump. Just like an engine with the sensor in the pan or dry sump tank, I want to know the temperature of that oil in the trans.
