I have a 2000 Ram 1500 with 183000 miles on it. Bought used because I needed the 5.9 liter to tow a trailer. Got it home and went to install a tranny cooler. Had to identify which line was which to the radiator tranny cooler, so I disconnected one line to the radiator, and put it in a bucket, and had the wife start the truck for a second. Found the fluid to be fairly brown. Mind you, the truck shifted fine at this point. So I drained what fluid I could by just dropping the pan, and blowing out the radiatior cooler. Put in a new filter and topped of the fuild with new stuff. Finished installing the tranny cooler. Later hooked up the trailer and took a trip. I live in Arizona, so it gets pretty hot here. Drove from Phoenix up to the Greer in the White mountains. There was quit a bit of straining going up the mountain roards. On the way home, the truck didn't want to shift into the last gear. I'm assuming that's overdrive. Now I know there is a lot of talk about weather you should or should not tow with overdrive on. Well the majority does. So anyway, about 3/4 the way home the only way it will shift in the last gear is if I leave up on the elcelerartor. I made it home okay, and read somewhere that since the oil was old, brown and gummy, after changing it someone recomended put in a quart of TransX. I tried it and it seemed to work. Now a few months later I'm seeing the same issue, but not every time. I ave read everying from that I need a total rebuild, to the overdrive solenoid is bad, some kind of electrical harness is bad, to connections on the firewall are corrodied. Who in the heck do you believe? I really don't want to spend the money on a rebuild job if it ends up being something simple. Who can you trust? Not sure where to go from here? Thought about changing the fluid and filter again, since teh TransX is still in the system.

 

Do not tow in overdrive. That is one of the fastest ways to kill your trans. You generate an awful lot of heat in O/D, and heat is the best way to kill your trans. How does the truck drive unloaded? Does it shift ok then?

 

One reason there is an overdrive button to turn it off is for towing. Dont tow heavy stuff in overdrive, keep it in 3rd gear by turning overdrive off

 

Okay so I won't do that any more. But maybe the damge is done. Hate to take it to a tranny place, all they want to do is say, Oh it needs a rebuild. So could it be some type of solniod or something else? How can I tell? Maybe it's some thing I can change out, with out pulling the tranny?