Transmission Fluid Leaking For 1999 Honda Passport

The transmission pan is the first place I would check. The pan gasket dries up over time and starts to leak. The pan is under the front of the car, near the oil pan. Oil pans are usually smooth, while tranny pans are finned or grooved (to disperse heat). Not hard to replace, but very messy work. 

The next place to check would be the metal lines that go from the tranny into the radiator and back out the radiator and into the tranny. Check to be sure they are tight, but don't over tighten them. They are easily damaged.

The tranny fluid filler tube can also leak. Check where it goes into the tranny body. There is a rubber O-ring that can dry up and cause it to leak in that spot. Should be an easy fix, if that's the problem.

If you still can't find the leak, you will probably have to take it to a garage. The only other options I can think of is a cracked torque converter or the converter gasket is leaking. Both of those problems are a pain to fix and should be done by a mechanic who is experienced working on transmissions..