2001 Dodge Ram 1500 Overdrive light comes on

My O/D lamp lights and the transmission comes out of overdrive while driving at highway speeds (typically 60-70 mph). This behavior just began today, I am not towing and the ambient temperature is around 50
degrees. One time the Transmission Hot indicator came on, but went out after I stopped, turned off the engine and restarted. If I stop and turn off the engine, then restart, the O/D indicator goes out and the transmission works fine for probably 15-20 miles, then the routine starts over. The transmission has plenty of fluid, still red, but I do smell that telltale hot "something" smell when I walk past the radiator. I have never changed the transmission fluid/filter. Should I have the dealer change it and adjust the bands as the owner manual says? Any other ideas?
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The transmission will drop down to 3rd gear if the fluid gets too hot - I suspect that's what's happening to your truck. Or, at least, it _THINKS_ the fluid is getting too hot. Yes, I would get the fluid/filter changed (should have been doing this every 24K), and have them check for a plugged cooler. With a proper scan tool, you can read what the computer thinks the transmission fluid temperature is, and read the actual temperature via an infrared thermometer on the cooler supply line. If the two readings are vastly different, the temp. sensor (part of the governor pressure sensor) is probably bad, and would need to be changed.
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snipped-for-privacy@hotmail.com wrote:

First have the fluid completely changed, not just whats in the pan. Make sure the pan is dropped and filter changed. Since you have a 2001 I'm assuming the fluid is way past it's intended life and the filter is possibly clogged. That would cause things to heat up. Hopefully no damage has occurred.
I change my fluid once a year or every 20K. I do tow sometimes though.
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