Its function is to bypass the external cooler so that the transmission can come up to temp. In cold climates, without the bypass, it may keep the fluid too cool and the transmission would not work the way its designed to work.

Quote Originally Posted by Ramsey View Post
Boy thats weird ,I cant believe ive never heard of such a thing,a bypass in the cooler?wtf will they think of next,?Im goin y is this guy asking about a trans cooler and a throttle body bypass?lol.what a nerd.lol.jokes on me.I guess you learn somethin new everyday.I thought i was pretty knowledgeable.so y do these passages only work when the fluid is cold ?Enlightin me.