Reverse not engaging, 2001 2.4l Automatic

Need help guys! Just got this 01 Tacoma 2wd 2.4l Automatic. Truck runs great and it drives perfectly fine in Drive, but it has trouble engaging into reverse.

SO when i put it in reverse, it just acts like it's in neutral. SOMETIMES it will go into reverse fine, other times it takes a few seconds and then clunks in, other times i have to get the truck rolling a little bit and then it will finally clunk into reverse.

Any ideas what this could be? hoping it's not in need of a rebuild. I checked the tranny fluid and it's gray and looks overfilled so i'm planning to drain the fluid tomorrow and replace the filter. Is there any chance this could fix it??

also, i read that draining the fluid only gets out about 1/4 of the total fluid in the tranny, how can i get ALL of it out so i can do 100% new fluid in it?

any advice helps and please share your stories if you had a similar problem, thank you!

 

Pop the pan off first and go from there . If the fluid is grey , its usually a sign of metal contamination .
If you have a camera , take a picture of the magnet laying in the pan before you do any cleaning . You may be wasting 100 bucks on a trans service and filter .
Reverse is fully mechanical on the A340 series transmission .
Here is a diagnostic link http://www.tacomaworld.com/forum/te...warner-340-series-transmissions-write-up.html

 

So are you thinking the trans is in need of a rebuild then?