Auto Trans Fluid - Flushing DIY

I want to flush ATF by pulling off the return hose and running the
engine to squirt out the fluid from the torque converter.

Here is my question.
How do I know which is the return hose?

I did a trans service on Dodge Caravan last weekend. Dropping pan and
replacing filter went fine. After reinstallation of the pan, I went on
flushing.

I pulled off one of the hose at the trans case side, assuming it as the
return hose. Plugged the hole with a plastic thingy.Put the hose into a
big glass jar, set up a mirror to watch the hose and jar. Started the
engine and put the gear into D.

Bang~ What a disaster! It was a TOTAL MESS. The plugged hole was
actually a pressure pump line. The fluid banged out of the hole and hit
the radiator to my garage floor. End of story, so much for DIY.

Say, it took tremendous efforts to clean up my garage floor

A lesson learned, I don't want to make the same mistake. Anybody knows
how I can find the AFT return hose on Sonata-99 ?

 

Honestly, I don't know which one is return. You could disconnect both
hoses from the trans and add your own hoses on the lines and put both in a
pan. Then reconnect the one that has fluid coming out and then put the
other hose in the jar/bucket/whatever.

It was much easier when they labeled the fittings "in" and "out."

 

The return line is usually the upper one coming out of the
radiator/intercooler. I have not done this on a Hyundai yet, but on other
vehicles I've owned I have taken a piece of brake line with the proper size
connector, and bent it so that I could remove the return line from the
radiator and screw in my bent line. The line was bent so that it would
point down into a bucket to catch the pumped out fluid. On some cars I
could simply put a 90 degree bend in the line and run straight down inside
the engine compartment. On others I bent it so that it came up and over the
grill and down.