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I know there has been a lot of discussion on transmission Temperature, especially when towing.
Here is what I got back from Jeep.

From Jeep Customer care:
My 2021 Limited with Tow and AD2 has these limits (they used my VIN).
DFJ 9-speed 948TE 4WD Auto Trans.
I would imagine The 9 speed Transmission in general has these limits with the non Tow and no AD2.
Tow and AD2 just add extra cooling to keep it within those Max. limits.

Normal operating Temperature: 230F and below.
Transmission temperature warning light: Turns on at 240F


Depending on what you tow, that is weight, 230F is the Maximum temp you should ever be be at.
The dash warning will light up at 240F.
And I would guess that would only come close if it was a hot day and you were towing max load (4500lbs).
My 2014 Cherokee towing an approx.1800lb boat I was at 170F in general. No tow it was in the 150F area.
My 2021 Cherokee without towing was in the 150-165F area on the highway. I have not towed the boat yet. But I would Imagine
it will be similar to my 2014 as the numbers look pretty close without towing.
Add some tow weight and hills and I am sure you will climb those numbers close to 200 or a bit over.

I hope this information can put some minds at rest as to where that Temperature should be.
It sure did for me!!!!
 

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Thank you for this official information.
This is something I have been wondering since I bought the Jeep and this is the first official number from Jeep I have seen.

I wonder what temperature the transmission oil cooler thermostat (yesterday I found out there is such a thing by browsing on rockauto) opens to let fluid into the auxiliary transmission cooler...

BTW, if anyone is curious:
https://www.rockauto.com/en/catalog/jeep,2015,cherokee,2.4l+l4,3308798,transmission-automatic,oil+cooler+thermostat,16221
 

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Admittedly, I live in Alberta not Arizona, and I haven't done any towing in serious mountains, only the foothills of the Rockies, but I tow a >4,000lb travel trailer and I can't recall ever seeing transmission temps over 200°F. Suggests the auxillary transmission cooler works well and keeps things well within the designed operating limits.
 

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Thank you for this official information.
This is something I have been wondering since I bought the Jeep and this is the first official number from Jeep I have seen.

I wonder what temperature the transmission oil cooler thermostat (yesterday I found out there is such a thing by browsing on rockauto) opens to let fluid into the auxiliary transmission cooler...

BTW, if anyone is curious:
2015 JEEP CHEROKEE 2.4L L4 Oil Cooler Thermostat | RockAuto
Ok, I answered my own question in case anyone else is...curious. The transmission oil thermostat will open to circulate oil into the auxiliary transmission cooler at ~ 180F:

https://derale.com/product-footer/product-instructions-footer?download=152:15719&start=140

That means the auxiliary cooler isn't even being used during 90%+ of the time.
In retrospect, the "auxiliary" part should have been the tip-off.
 

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Mine got up to 209 degrees coming down from a mountain camping trip... Kept it in 3rd gear instead of riding the brakes.
Trailer is about 2k lbs, I have the 2.4l

Interesting that towing up hill it only got to 197.... Downhill harder maybe?

Going up the hiss was around midnight, coming down was 6pm... May be related
 

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Mine got up to 209 degrees coming down from a mountain camping trip... Kept it in 3rd gear instead of riding the brakes.
Trailer is about 2k lbs, I have the 2.4l

Interesting that towing up hill it only got to 197.... Downhill harder maybe?

Going up the hiss was around midnight, coming down was 6pm... May be related
That's interesting. I'd think that uphill would be tougher on the transmission than downhill even if you are engine braking the whole way...

Having said that, 209 is not even close to the thermal limits of the transmission fluid.
 

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Discussion Starter · #8 ·
Ok, I answered my own question in case anyone else is...curious. The transmission oil thermostat will open to circulate oil into the auxiliary transmission cooler at ~ 180F:

https://derale.com/product-footer/product-instructions-footer?download=152:15719&start=140

That means the auxiliary cooler isn't even being used during 90%+ of the time.
In retrospect, the "auxiliary" part should have been the tip-off.
Actually the transmission needs a minimum temperature to work properly. It is designed to operated at a specific range. If the aux cooler was on all the time it would probably keep the fluid to cool for the transmission to work properly.
That is my understanding.
 

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It doesn't need a minimum operating temperature to work properly. It works at all temperatures. If it didn't how would people who live in very cold climates manage to drive their vehicles? There is specific shift patterns that are used until the fluid is warmer but it still works regardless of temperature.
 

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Transmission got up to 192 this weekend going up to the cabin.
This is on a highway going ~55mph uphill, going down to 35mph for the last 2000 vertical ft.
Downhill on the way back, it didn't even warm up up to 150 until we were most of the way down the mountain.
I did some engine braking in 3rd for the first 15mi, but the transmission temp was still very cold, then it was 5th all the way down so I wouldn't have to use my brakes.
 

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Transmission got up to 192 this weekend going up to the cabin.
This is on a highway going ~55mph uphill, going down to 35mph for the last 2000 vertical ft.
Downhill on the way back, it didn't even warm up up to 150 until we were most of the way down the mountain.
I did some engine braking in 3rd for the first 15mi, but the transmission temp was still very cold, then it was 5th all the way down so I wouldn't have to use my brakes.
What kind of gradients and what elevations do you hit? Sounds like it's pretty steep that last bit up?

I've been impressed with how cool the transmission in the KL stays. Going to our cabin are several 6-7% grades. Over 180 miles, the total ascent is 16,250 ft with 11,470 given back (4,780 difference in altitude with a LOT of hills in between). I think I've only hit 190+ on a couple of occasions when it's been really hot out and I pushed up the steepest grades 75 MPH+. Gotta get out of that heat ASAP! I run the adaptive cruise control probably 95% of the way. Don't know how much engine braking is used by adaptive cruise control, but I know my 2.0L Turbo doesn't have much to begin with.

My JK seems to break 190 backing out of the driveway! Not really, but it does get pretty hot doing that same drive. I have "guaged" it so I can keep an eye on transmission temps and put in an aux trans cooler which helps some. My RAM gets REALLY hot doing that drive, but I'm usually towing. 75 MPH+ going up 7% grades would probably cook the transmission right out of the RAM. The JK couldn't hit 75 MPH+ downhill with a 74 MPH tailwind, so it stays about as cool as it can be.

Don't have those worries with the Cherokee.
 
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What kind of gradients and what elevations do you hit? Sounds like it's pretty steep that last bit up?

I've been impressed with how cool the transmission in the KL stays. Going to our cabin are several 6-7% grades. Over 180 miles, the total ascent is 16,250 ft with 11,470 given back (4,780 difference in altitude with a LOT of hills in between). I think I've only hit 190+ on a couple of occasions when it's been really hot out and I pushed up the steepest grades 75 MPH+. Gotta get out of that heat ASAP! I run the adaptive cruise control probably 95% of the way. Don't know how much engine braking is used by adaptive cruise control, but I know my 2.0L Turbo doesn't have much to begin with.

My JK seems to break 190 backing out of the driveway! Not really, but it does get pretty hot doing that same drive. I have "guaged" it so I can keep an eye on transmission temps and put in an aux trans cooler which helps some. My RAM gets REALLY hot doing that drive, but I'm usually towing. 75 MPH+ going up 7% grades would probably cook the transmission right out of the RAM. The JK couldn't hit 75 MPH+ downhill with a 74 MPH tailwind, so it stays about as cool as it can be.

Don't have those worries with the Cherokee.
Unfortunately, I don't remember the exact grades. It's the Sonora Pass (Hwy 108) in California, driving from the SF bay area, so it's a total of just over 5000ft elevation change (sea level to a bit above 5000ft elevation), so it's not the steepest part of the pass, which on wikipedia is 7-28%.
There are some pretty steep areas, and there are long, steep sections with speed limit of 65mph following a traffic light, so accelerating uphill from stop to 65+mph.
The last 15 miles the speed limit decreases to 35-45 because of how windy it gets, and the last mile it goes back up to 55, so it's a real mix.
I also noticed that the engine coolant temp was 210-230, cooling back down to 190 quickly after cresting a small hill and having a respite from climbing.

I had a trunk full, 2 people and a baby in the car, and like I said, AC was on coldest setting (but not MAX AC) and fan was on medium speed.
I did have to pass some slower trucks on sections where the road split into 2 lanes per direction.

Engine Oil temp stayed at 2/3 most of the time on the way up, as it always does when coolant temp is elevated.

I wasn't worried, but it did seem warmer than what I'm used to... But the majority of the time we've gone to the cabin in the past (before baby) has been at night, so ambient temps are much cooler and AC is not on.

I don't know what role the active grill shutters play in this because they do close at higher speed and reduce airflow over the radiator and inside the engine bay compared to the 3.2L and 2.0T equipped cherokees.
 
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