Which trans line is the return?

Can somebody help me identify which trans line is the return from the radiator? I have mounted a cooler just waiting for info on which line to run to it. My 2002 Tacoma TRD 2.7L 2x4, has both lines on the bottom of the radiator, opposing sides. One driver side and one passenger side so to speak. Thanks in advance.

 

Driver side is return i believe. If its a 4 banger with no cooler its not a TRD by the way.

 

Its not a 4x4 but 2x4. I was hoping it was the passenger side but we will see...

 

Upon some searching it seems to be the line on the driver side down near the return radiator hose for the 2.7 4 banger.

 

I've got my trans temp sending unit coming out of the trans which is then connected to the passenger side.

 

The coolest one.

 

I tried the touch test and they both feel the same to me, relatively easy to touch so that didn't work for me. I am thinnking it might be the passenger side as well because I traced that line to where it attaches to the transmission closer to the rear of the unit. I found a link on the 4runner forums that identified that as the return. It looks the same as mine. Would a 3.5L auto be different than a 2.7 auto in terms of the return line?

 

The return line is the line furthest to the front of the transmission. The rear is the supply line.

 

http://www.yotatech.com/f2/one-transmission-return-line-183494/

 

The return is the lower and the rear most it dumps the cooled oil into the pan. If you are adding a cooler it will work either way but as the oil cools it want's to sink to the bottom so it is slightly more efficient to mount it that way. The trans cooler systems are not a sealed loop the hot oil comes out the top is cooled and just dumps back into the pan no valves no magic.

 

Bringing up old threads... but I've got a 2012 2.7l 4x4, I'm trying to identify the return line, from the radiator, to install a cooler. It appears mine 2 lines are on the driver side, but one on top, and one on bottom... been rough finding info so any would be great! Thank you!

 

Just FYI for most vehicles, the line exiting the transmission to the cooler will be the one that has the temp sensor on it right at the transmission. The return will not have one, unless newer vehicles have one to monitor the temp of the "cooled" atf.