Just replaced the PCM on my truck ('01 Ram 4X4, 5.2). Took it for a long run, and the transmission ran hot. First it kicked off the OD, so my first thought was that the PCM was bad (again). However, I kept going and then the "Trans Temp" light came on. Pulled over and let it cool, and it ran just fine until it warmed up, and the sequence started all over. I'm pretty sure it's more serious than a sensor...it smelled hot. Hasn't kicked out any codes either...

What are the likely causes? Could it be as simple as the cooler needing to be washed (externally)?

As always, all thoughts/help sincerely appreciated!

In the cooler line is a check ball , its purpose it to reduce converter drain back.

This ball can stick in the closed position and over heat it. Find it and remove it.

OK. Removed the check ball, took it for a test drive...no change. While I was crawling under it I noticed that there's a slight bit of transmission fluid on the bottom of the bell housing. It isn't enough that it dripped on my driveway, but I'm certain that it has developed a leak from somewhere in the front. I'm guessing it's somehow related to the issue(s) at hand.

One more thing from the test drive: Before the transmission got hot and kicked the OD off completely, if I put down the pedal enough to push it out of OD and into 3rd, sometimes it didn't want to shift back down into OD...other times it shifted back and forth just fine. If I put it in neutral (at 55MPH) and then back to "D" it would go straight into OD and drive normally. I was being gentle on it yesterday, so I'm assuming that's why I didn't notice this symptom then.

Any more ideas???

Did it run hot before you changed the pcm?The fluid burping out of the vent in the bell housing because its running hot.

What was the reason for changing the pcm?was it transmission related?

When the transmission temp see's an over temp it will shut down overdrive and lock up until it cools down.
I would recheck it for codes,you should have a overtemp code stored in the computer.

Didn't have any transmission issues prior to changing the PCM. I changed the PCM because I got the P0601 code and the issues that go with that...one of which is no OD. It did kick out code P0420 on the test drive today, and it had that prior to the computer going bad also. I do need to fix that, but I don't think it's related to the transmission issues. Will the computer store a code that doesn't appear in the self diagnostic display? Might solenoids cause such issues? I know nothing about these things...just reading stuff on the internet trying to get a clue.

I believe p0420 is a catalytic converter effinecy problem,is your truck running good?sounds like you may have a plugged converter.

The motor runs great. I replaced the cat about 2 years ago with a "high flow" unit, and I'm pretty certain it isn't clogged. I'm thinking I have a bad O2 sensor. I dropped it off at a shop a little while ago. We'll see what they say...