Transmission Overheating - anyone else?

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fuzznuts

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Land Cruiser 250 First Edition
I wanted to share my experience with the community in case others are having similar issues.

My Land Cruiser (1100 miles) is reporting overheated transmission fluid under certain conditions that my service center has been unable to replicate and therefore do anything about especially with the absence of any thrown codes.

On relatively slow (10-45 mph) winding paved and gravel roads that head up into the mountain near me, the transmission temp gauge gradually climbs to about 3/4 of the way to the red. If I continue on a dirt road that also puts the vehicle under load at slow speeds going up a hill the gauge will eventually hit the red and I will get a message that the transmission fluid temp is high and to pull over safely. This dirt road seems to be the trigger that actually overheats the transmission. The section of off-road trail is not tough trail and does not require low-range or even locking the center diff. Kias/Subarus have been on this part of road in the past.

I currently only able to read transmission temp sensor #1 from the ECU and between 245F and 250F the vehicle is overheated. At around 235 the gauge is 3/4 of the way towards the red. At one point I watched the temp gauge, in the span of about 4-5 seconds, go from blinking red (overheated) then drop to the middle point and then move back up to just below the red all while not moving.

As another data point, I am routinely in the 200F-215F while putzing around town which seems to be on the warm side however I do not really know what the expected normal operating temp is. I have also noticed that from about 130F to 215F the transmission temp gauge remains in the middle.

I am not able to replicate this issue while driving in the city or highway driving in the mountains.

Is anyone else experiencing anything similar? I would be curious to know what temps others have been observing around town and under load like mountain or light off-road driving.
 
fuzznuts said:
I wanted to share my experience with the community in case others are having similar issues.

My Land Cruiser (1100 miles) is reporting overheated transmission fluid under certain conditions that my service center has been unable to replicate and therefore do anything about especially with the absence of any thrown codes.

On relatively slow (10-45 mph) winding paved and gravel roads that head up into the mountain near me, the transmission temp gauge gradually climbs to about 3/4 of the way to the red. If I continue on a dirt road that also puts the vehicle under load at slow speeds going up a hill the gauge will eventually hit the red and I will get a message that the transmission fluid temp is high and to pull over safely. This dirt road seems to be the trigger that actually overheats the transmission. The section of off-road trail is not tough trail and does not require low-range or even locking the center diff. Kias/Subarus have been on this part of road in the past.

I currently only able to read transmission temp sensor #1 from the ECU and between 245F and 250F the vehicle is overheated. At around 235 the gauge is 3/4 of the way towards the red. At one point I watched the temp gauge, in the span of about 4-5 seconds, go from blinking red (overheated) then drop to the middle point and then move back up to just below the red all while not moving.

As another data point, I am routinely in the 200F-215F while putzing around town which seems to be on the warm side however I do not really know what the expected normal operating temp is. I have also noticed that from about 130F to 215F the transmission temp gauge remains in the middle.

I am not able to replicate this issue while driving in the city or highway driving in the mountains.

Is anyone else experiencing anything similar? I would be curious to know what temps others have been observing around town and under load like mountain or light off-road driving.
Click to expand...
I can't say I've experienced high transmission temps by looking at the gauge but 250 seems high, what did you use to measure these temps?
1725752719092.png
 
My scanguage. I believe there may be 2 sensors but I have only found the codes for temp sensor #1 and I am not sure where that sensor is located.
 
tempImageMyPo4f.jpg

  • Bottom left is engine oil temp
  • Bottom right is transmission temp #1
  • Top right is water temp
The vehicles transmission temp gauge was just outside of the red at this point. I have been able to overheat the transmission 4-5 times now pretty consistently.


IMG_2211.jpeg
 
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Reactions: lcq
This is a fascinating problem. A couple of things: (1) it does not seem to be an indication problem since you only have it under specific conditions, and (2) the transmission should be way more robust than this (i.e., run much cooler). Have you flushed the transmission and changed fluid and filter? I would do that for sure. It's possible you have a factory machining defect or debris lodged in one of your hydraulic "circuits" that may be giving you an issue. A flush is not going fix a defect, but it could dislodge any possible manufacturing debris.
 
I have not done anything with regards to transmission fluid. I am curious what a drain/flush would reveal however and I have discussed with the service center doing exactly what you have said, flushing the transmission but nothing done yet. I will have to pay to have anything done since Toyota will not authorize anything since the problem can not be replicated and there are no codes either and I have been reticent to jump in to throwing money at the situation for troubleshooting purposes but will do at some point as it won't happen any other way.

I have been a little disappointed in the low end power for off-road use and now the transmission problem has left me overall disappointed very early on in the platform as a whole.

I think it would be interesting to see what temps folks here are recording for city and mountain/off-road driving as I am seeing readings all over the place.
 
It’s possible transmission updates could fix the issue. The transmission could be slipping the torq converter and clutches more than needed. When Toyota gets the info then they can create fixes.
 
You could try to put the transmission at max 4th or 5th gear. It may be hunting for a gear.
 
I will share a story with you. Not sure if this will help. Right after I bought my FJ in 2014 I moved from NM to Oregon. I moved my stereo and my vinyl records. I have a big stereo and over 3,000 vinyl records. I had the double axle u-haul. The biggest trailer they will let an FJ tow. It was fully loaded. Nothing will work a transmission like towing. My route took me through Durango, Silverton, Ouray. Over the Rockies, then later over the Cascades. To preserve my brakes I was down shifting the transmission a LOT. Temperatures did rise, but never approached redline. I could even smell things occasionally, so I know I was stressing it. When I got to Corvallis, the first thing I did was take it to the Toyota dealer and had them flush and change fluid and filter. Their inspection showed no damage, everything was fine. Many years later, no more towing, but every kind of off-roading you can think off, I can't get the transmission temp to move. It is under no stress. And that is how it should be. I bet other LC owners don't see their temps move much at all unless they are towing something. Just moving the vehicle should be no sweat for the transmission. Going up a mountain? Pfft... You, my friend, have a problem in your tranny of some kind most likely, as it should not do what it is doing. My $0.02.
 
This person is observing something similar in terms of elevated transmission temps albeit not actually overheating.

And here seems to be another report of high transmission temps. Perhaps something is wrong with my transmission specifically but perhaps I am not unique with regards to this problem either.
 
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The LC250 probably needs a stand alone liquid to air heat exchanger put on.

Manufacturers have started to omit these to cut costs and run higher transmission temps because the hotter transmission fluid is thinner and less resistant to pumping resulting in marginal fuel economy improvements.
 
fuzznuts said:
This person is observing something similar in terms of elevated transmission temps albeit not actually overheating.

And here seems to be another report of high transmission temps. Perhaps something is wrong with my transmission specifically but perhaps I am not unique with regards to this problem either.
Click to expand...
I have a scanguage as well, if you will share the code you used to input sensor #1, I'll do the same and run a few of the trails here and report back.
 
A couple questions.

Does the LC have a transmission cooler? If so, does it have a fan?

And while we're on the subject, does the turbo have an intercooler? Just curious.

Anyway, if you're not too far, I could drive up there and take my LC over the same trail to see if my transmission gets hot.
 
Colorado said:
A couple questions.

Does the LC have a transmission cooler? If so, does it have a fan?

And while we're on the subject, does the turbo have an intercooler? Just curious.

Anyway, if you're not too far, I could drive up there and take my LC over the same trail to see if my transmission gets hot.
Click to expand...
The transmission cooler is built into the radiator. The turbo does have an intercooler.
 
Op what is yor trans temp read after the car sits overnight? I am wondering if you have a faulty temperature sensor.
 
I have a scanguage as well, if you will share the code you used to input sensor #1, I'll do the same and run a few of the trails here and report back.
Click to expand...

TXD - 0701221AAA
RXF - C462051A36AA
RXD - 3008
MTH - 00090005FFD8

Anyway, if you're not too far, I could drive up there and take my LC over the same trail to see if my transmission gets hot.
Click to expand...

Feel free to DM me and I can share the route, it includes driving through Golden Gate Canyon State Park

Op what is yor trans temp read after the car sits overnight? I am wondering if you have a faulty temperature sensor.
Click to expand...

69F on cold start this morning after sitting overnight.
 
fuzznuts said:
TXD - 0701221AAA
RXF - C462051A36AA
RXD - 3008
MTH - 00090005FFD8



Feel free to DM me and I can share the route, it includes driving through Golden Gate Canyon State Park



69F on cold start this morning after sitting overnight.
Click to expand...
I used the scan gauge on a 30 min trail ride with moderate inclines in 4LO and only got the transmission to 165 degrees, however it is only in the high 40s outside. I did compare the transmission oil pan via IR gun and it registered 140 degrees at its hottest point, so I'm thinking sensor #1 may be the torque converter temp. Next weekend I'll do an extended run with the forecast in the 80s for another data point.
FYI my 4Runner TRD PRO tranny temp was in the 225-235 range pulling a 5,000 lb trailer up grade in gear 4.
 
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fuzznuts said:
TXD - 0701221AAA
RXF - C462051A36AA
RXD - 3008
MTH - 00090005FFD8



Feel free to DM me and I can share the route, it includes driving through Golden Gate Canyon State Park



69F on cold start this morning after sitting overnight.
Click to expand...
Temp looks normal, assuming ambient temperature was also in that range. Do you also get random temperature spikes in city driving, similar to the ones you described on dirt roads that may also indicate an issue with the sensor?

I am leaning towards a temperature sensor issue since I cannot see how the temperature can move from 250 to 200f in about 4-5 seconds.

This will not be a very precise way to measure, but you can get a temperature gun and measure how hot the transmission pan is while the gauge shows it is overheating. If the pan is way below the sensor, the sensor is probably bad.
 
Thanks for the data point, berry802. I would be interested in what you see on a trail that does not require 4LO as this would be a more direct comparison. I could put my truck in 4LO on this particular trail and I suspect the temps would drop although it should be unnecessary and a more unenjoyable drive as a result. I have read other threads on Tundra and Tacoma forums where the general consensus was that 4LO was the answer to elevated transmission temps which I struggle to accept. These vehicles should not require to be in 4LO on roads/trails that Subaru's, Kia's, or a dude on a unicycle can drive up.

Setting aside the trail and whether 4LO would help or not, just as concerning to me is that on paved and gravel roads I am seeing reported temps up to 225F or so and up to 215F around the city.

Do you also get random temperature spikes in city driving, similar to the ones you described on dirt roads that may also indicate an issue with the sensor?
Click to expand...

I am not seeing temp spikes around the city, I routinely see 190-215 around the city.

I too also wonder if there is an issue with the temp sensor however it does seem the transmission is overheating. When the transmission is hot or overheating, it smells like burnt transmission fluid. I plan to use my temp gun on the next trip to track what the pan is running at.

I am leaning towards a temperature sensor issue since I cannot see how the temperature can move from 250 to 200f in about 4-5 seconds.
Click to expand...

I do not know what the reported temps were when this happened ( I did not have my scan gauge ). I only observed the car's temp gauge go from the red, down to middle, and then back to just under red. In another instance, where I had my scan gauge with me, I saw that at 244F the vehicle was saying the fluid was overheated but at 250F a few minutes later the vehicle temp gauge was out of the red and a "few ticks" out of the red. Given there is about an 85F temp range (130F - 215F) for what the vehicle represents as in the middle, it is hard to make sense of what is expected/normal.

So for me, again only being able to see temp sensor #1, I have worked out the below:
  • 130F-215F temp gauge in middle
  • 228F - temp gauge is a few ticks above middle
  • 235F - temp gauge is 3/4 way to red
  • 244F - temp gauge is in red, vehicle warning of overheated fluid
Taking a step back - what temps are others here seeing under normal driving conditions?
 
Last edited:
fuzznuts said:
Thanks for the data point, berry802. I would be interested in what you see on a trail that does not require 4LO as this would be a more direct comparison. I could put my truck in 4LO on this particular trail and I suspect the temps would drop although it should be unnecessary and a more unenjoyable drive as a result. I have read other threads on Tundra and Tacoma forums where the general consensus was that 4LO was the answer to elevated transmission temps which I struggle to accept. These vehicles should not require to be in 4LO on roads/trails that Subaru's, Kia's, or a dude on a unicycle can drive up.

Setting aside the trail and whether 4LO would help or not, just as concerning to me is that on paved and gravel roads I am seeing reported temps up to 225F or so and up to 215F around the city.



I am not seeing temp spikes around the city, I routinely see 190-215 around the city.

I too also wonder if there is an issue with the temp sensor however it does seem the transmission is overheating. When the transmission is hot or overheating, it smells like burnt transmission fluid. I plan to use my temp gun on the next trip to track what the pan is running at.



I do not know what the reported temps were when this happened ( I did not have my scan gauge ). I only observed the car's temp gauge go from the red, down to middle, and then back to just under red. In another instance, where I had my scan gauge with me, I saw that at 244F the vehicle was saying the fluid was overheated but at 250F a few minutes later the vehicle temp gauge was out of the red and a "few ticks" out of the red. Given there is about an 85F temp range (130F - 215F) for what the vehicle represents as in the middle, it is hard to make sense of what is expected/normal.

So for me, again only being able to see temp sensor #1, I have worked out the below:
  • 130F-215F temp gauge in middle
  • 228F - temp gauge is a few ticks above middle
  • 235F - temp gauge is 3/4 way to red
  • 244F - temp gauge is in red, vehicle warning of overheated fluid
Taking a step back - what temps are others here seeing under normal driving conditions?
Click to expand...
Another possibility is that there is excessive slippage due to gear hunting or the torque convertor not locking up, and that causes overheating. Both of these would be software issues that need to be patched.

Have you tried putting the transmission in manual mode and selecting a relatively low gear, or using the tow/haul option? You may also be able to see the toque converted lock/unlock status with your OBD scanner.
 
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