I have a 2004 4.0L V6 XLT with about 252,000 miles on it. I had the transmission rebuilt last week and only put 300 miles on it before my overdrive light started blinking on my dash. It first happened when I was accelerating to get on the highway yesterday, but it happened once more today when I was sitting at a red light. I've noticed it slips a bit around 2000 RPMs after the light comes on, any advice?

 

Flashing OD light means computer has detected a problem with transmission and has set codes for the problem(s) it detected, its like the CEL(check engine light) but for the transmission

Transmission codes are P0700 to P0803 so there are ALOT of possible codes, seen here: https://www.therangerstation.com/tec...II_codes.shtml

Scroll down to the P0700's
So guessing is out of the question, lol

Transmission shop will have a reader that can "see" transmission codes, not all OBD2 readers can
I would stop by and have them read the codes, WRITE THEM DOWN!!!

It could be something as simple as ISS sensor is unplugged, or 16 pin connector didn't get pushed on tight, the CODE will tell you what to check

Automatic transmissions are not complicated on how they work, and all the hard work was done in the designing, but.............
There are several interdependent systems that make diagnosing a specific problem hard to do just with symptoms

i.e. you come out in the morning and your tire is flat, that's the symptom of a problem
Diagnose it
"the air leaked out", lol
Yes, but why
maybe a nail or ?? punctured the tire when driven last
95% of the time thats the best "guess"
But 5% could be someone smacked a curb and bent the rim so it leaks, someone LET THE AIR OUT, tire has a defect and split, tire has a worn spot that's leaking, these are all valid "guess's" as well
And thats JUST a flat tire, automatic transmissions have a few more possible failure modes

You have to get the codes and go from there