The radiator cooler isn't hooked up.

 

That's really odd as you shouldn't have O/D. I know when I had my 46re rebuilt for my Durango they told me that bypassing the radiator cooler will void the warranty, as it will cause the transmission to overcool which can cause damage.

 

It's been 7 years now and it's shifting like it did before all those 7k to 10k pound pulls that burned up my old transmission. The guy that rebuilt mine said that he wouldn't warranty a 2nd gen ram transmission rebuild if the owner insisted that the check ball stay on the lines but he said that he thought it was best for me to have the aftermarket cooler.
If overcooling knocking out overdrive were a concern then you wouldn't have overdrive in a factory setup until you got about 10 minutes down the road in winter because the radiator doesn't warm up until the thermostat opens up. I've had mine warming up long enough for me to scrape the ice off the windows (probably 20º) then hopped in and booked it down the road with no overdrive issues and no heat until I was half way to work.

 

Yeah, according to theory, (and the FSM) the PCM won't go into O/D until trans temp reaches 108 degrees. However, I don't think that is correct, as my truck will shift into overdrive within a mile of my house, even on the coldest days. (sub-zero temps..... sometimes double digit sub-zero temps.....) Unless trans fluids heats up REAL fast, there is no way that it gets to 108 degrees in less than 500 feet. (I don't let my truck sit and idle to warm up, can't afford the gas for that.... it already gets horrible gas mileage.) And that goes for both my 96 with the 5.9 gas, and also my 98 with the 8.0.

Also, given that most 95 and older trucks, the PCM doesn't have a clue what trans temp is...... I am quite sure it doesn't wait.

 

My truck reaches 108 within 3 minutes of starting that's in 32° weather

 

Hhhhmmmm...... If I had a scanner that would tell me that info, I would be REAL curious to monitor it some morning. I hit 45 mph or so within about a minute, minute and a half, of startup.

 

I would always let my truck warm up for a minute at least, and I had OD all the time... but even when I didnt let my truck warm up I still seemed to have OD, I couldnt give a reliable answer.

 

Now that going 15mph and starting her up and going. But I always assumed without the radiator cooler it wouldn't warm up with the engine

 

My engine most certainly does not hit 108 in 60-90 seconds on those truly cold michigan winter days......

 

Can't attest to the really cold days yet