I have the secondary external cooler on my truck. I want to put the temp sensor from the hottest point in the trans system. I know you tap it in with the feed to the radiator, but I am unsure of what line that is.

 

It comes out of your trans and runs to the top drivers side of the rad then out the bottom to your external cooler and back to the trans.

A lot of guys put the T in closest to the trans or under the rad. I added mine just before it goes into the top of the rad. I wanted to keep it out of the weather (read road salt). I am guessing that the fluid gets there fast enough to only lose a degree or two.

 

thanks!