So, I've basically been driving on what feels like prayers the last week as the temperature light for my transmission keeps coming on and has been doing so for the last week. I have a 2000 Durango with the 4.7 and 45RFE transmission (I just hit the 172,000 mile mark and I bought it at 154k) and after changing the speed input sensors to solve a hard shifting problem with 2nd and 3rd gears (1st gear was not fixed but it doesn't affect driveability even a bit) and a week later now I start getting the transmission temp light coming on after either several minutes of driving at 35-40 or when I accelerate up to highway speeds. Now, I've been driving on it including unfortunately several 50+ mile trips in this week due to things outside my control and thankfully nothing has happened yet. I don't know what if any work the previous owners did but I do know the transmission fluid is ancient and so I've gone ahead and ordered a new tranny oil pan (I want a drainplug to make it easier in the future) and a filter and gasket set off rockauto and plan to do the work this coming week and need all the advice possible to replace and clean anything I can to make sure my tranny gets through this as I can't afford a new car right now and I'm stressed out thinking I could kill this car ahead of it's time. If anyone has more questions about I'll answer to the best of my limited car knowledge.

 

​​​​A lot of people skip replacement of the little round rubber seal for the sump filter because they're scared they will mess it up somehow. This is a fair concern and some people get away with skipping it. However, it's obviously better to replace it, it's included for a reason.
The way I do it is use a open ended wrench to carefully pry the old seal out. Use a towel over the wrench so it doesn't gouge the surface the seal presses into. Dip the new seal in ATF and pound it into place with a socket over it. You'll hear the "thud" sound change when it's fully seated and can also run a 90* pick around the edge to feel if it's fully seated.

Also make sure your new sump filter matches the old one. Some people accidently order a kit with a sump filter that doesn't reach into the pan far enough.

I use a Felpro gasket on the pan. Cheap gaskets have screwed me more than once.

Be careful not to over tighten any bolts they strip easily the tranny is aluminum.

Make sure it's full of ATF+4 when it's all back together. Service charts will tell you it takes like 5 quarts to refill after a fluid/filter change but IIRC it took me 7 quarts each time.

No other special tips come to mind at the moment. Just take your time, I'm assuming you already researched what to do and understand the basic concept of what needs to be done.

Good luck have a fun ATF shower and hopefully it has a positive impact on your issues.

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Thanks for the advice! I'm still doing some research and getting a last few things together. One of the things I still have questions about is a DIY fluid flush using the transmission cooler hoses to alternative pump new fluid in and old fluid out to easily replace all the fluid. This isn't something I've seen commented on to much and I was wondering if this is okay to do along with replacing the filters etc. Another thing I'm making sure of is the torque specs are the ones on this site accurate for example?
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Also, some good news is that a relative of mine has a shop in the area they said I can come to Sunday so I'll have one thing going easily for me thanks to that.

 

I've never done a full flush like you mentioned and it also doesn't seem to be a common practice from what I see/hear.
Some people say it can ruin your transmission especially if you already have issues. I don't know how much of that I believe but it's a widely argued topic.

Just about everybody seems to stick to the normal drain/fill service technique. If you want to get more old fluid out you can always just change it again after driving around the block a couple times. Would be super fast with your new drain plug.

The torque specs for the pan bolts are very similar to what I did. I did not torque the filters. Just used best judgement.


On a side note, another tip is don't forget to put your magnet from the old pan into your new pan! I did that on one of my trucks. Thankfully the new pans plug had a magnet built in anyways so I just roll with that. But if you remember the old magnet too that's great.
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Well I return to report I have successfully completed the fluid and filter change and put almost 200 miles on it without issue since and also managed to change the sensor on the rear of the transmission which I discovered was leaking fluid badly into the connector. Which since the new sensor and all this hasn't stopped the light from coming on leaves me to either assume I need to replace the pig tail as well or there is something else going on to cause the Transmission Temp light to keep coming on. I'm at wits end now and really just want this light to stop coming on every time I run to the corner store.

 

I know on the older ones, with the magnum engines, there was a check valve in the trans cooler line running to the radiator that liked to clog up, and give the same problem. No idea if yours would have one or not. How long do you have to drive before the light comes on? Has it been getting to be a shorter interval over time?

 

Could be the thermo valve the cooler lines are part of if it has one or maybe the torque converter. The temp sensor is part of the valve body.

 

I haven't timed it but the interval seems to have stayed the same usually a few minutes sometimes a bit longer and now after changing the fluid if I end up driving for awhile under 30 it sometimes just goes off and stays off until I speed up again. Occasionally when it first showed up just turning the engine on and off again before driving again would buy me a minute or two before the light came on. So no signs of anything getting worst and the fluid and filter change seems to have had helped a bit going by how going under 30 now will cause the light to go off after a bit.
What about the torque converter could be causing the light to come on like this? How hard would it be for me to replace this sensor? From what I've seen online while doing research it should be possible to remove the valve body with the transmission still inside my vehicle.

So at this point I take it I should take a look at the cooler lines from the transmission for this valve and also see about replacing the temperature sensor in the valve body? I feel like it has to be something that isn't too serious as I've had to drive 50+ miles repeatedly on a regular basis still without any actual signs of overheating occurring.

 

Okay, well I did some more Googling and changed my search terms up a bit and the top result was this manual on the 45RFE that says it is part of the solenoid pack on top of the valve body.

"Transmission Fluid Temperature Sensor - is located in the Solenoid Pack/Transmission Range Sensor and is a thermister that the TCM uses to moniter transmission fluid temperature. Overdrive Cancel Switch- located on the shift lever and cancels overdrive operation."

I just want to make sure if is this correct the sensor is part of this pack? If so I'll be looking for that check valve first as I'll have to save up a bit to replace that pack as Rockauto has it for a bit over $500 and a I saw one or two on Amazon in the $200 range. Also from what I understand depending on the color of the connector for the solenoid pack I will also have to change a plate next to it on the valve body?

Edit: Given how expensive this is pack can be would it possibly be worth the bet of going to a junkyard to pull a used one?

 

Think I would be more inclined to verify the fluid temp before replacing anything. The little point-and-shoot IR thermometers are pretty cheap these days.