2025 4Runner Transmission Overheating on Climbs Off-Road

[Gunnison]

Just because there isnt a dipstick doesnt mean you have to unseal anything. How do you think the fluid gets put into the transmission?

By unsealing I mean doing what you mentioned below, getting under it and doing that check versus just being able to check it from under the hood. That would have been “extra”’at the dealership.

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[HVLA]

By unsealing I mean doing what you mentioned below, getting under it and doing that check versus just being able to check it from under the hood. That would have been “extra”’at the dealership.

On a brand new vehicle? You need to find another dealership asap.

 

[Gunnison]

On a brand new vehicle? You need to find another dealership asap.

I know right, I already been to three and am going to try some more.

 

[Gunnison]

Just got the 4Runner back from the second dealer. They ran a health check and found no fault codes. They then ran the Record of Behavior (ROB) and found the two instances of high transmission temps. The first dealer I went to did not find this. The dealer that did created a Technical Assistance Case (TAS) with Toyota and it got assigned to a TAS agent to investigate. This was the first nationwide TAS created for this, so I humbly ask all Tacoma and 4Runner owners who have experienced this issue to take it to a dealer that will diligently inspect the ROB for diagnostic codes and have them create a TAS with Toyota. If Toyota has enough TASs then hopefully they will come up with a fix. Toyota did not say definitively whether or not this would be covered past warranty. Also, the 2024 Tacoma they gave us as a loaner had the same issue when we took it off-road. Thank you everyone for your posts on this.

 

[jarussll4]

Just got the 4Runner back from the second dealer. They ran a health check and found no fault codes. They then ran the Record of Behavior (ROB) and found the two instances of high transmission temps. The first dealer I went to did not find this. The dealer that did created a Technical Assistance Case (TAS) with Toyota and it got assigned to a TAS agent to investigate. This was the first nationwide TAS created for this, so I humbly ask all Tacoma and 4Runner owners who have experienced this issue to take it to a dealer that will diligently inspect the ROB for diagnostic codes and have them create a TAS with Toyota. If Toyota has enough TASs then hopefully they will come up with a fix. Toyota did not say definitively whether or not this would be covered past warranty. Also, the 2024 Tacoma they gave us as a loaner had the same issue when we took it off-road. Thank you everyone for your posts on this.

Almost the exact same thing that I am going through with my new 2025 Land Cruiser which has the same powertrain. I agree with you, if enough people report it, hopefully Toyota will do something about it.

 

[Gunnison]

Almost the exact same thing that I am going through with my new 2025 Land Cruiser which has the same powertrain. I agree with you, if enough people report it, hopefully Toyota will do something about it.

I was wondering if it was happening in the Land Cruiser, sorry you are experiencing it too. Yea, I know it can be a pain in the butt but taking it to the dealership and making sure they find it in the ROB and they file a case with Toyota seems to be the official way Toyota will keep a log of these instances.

 

[02SE]

If you're driving up a steep incline that requires 4wd, and doing so at a slow speed, you should be in 4Lo. This will dramatically increase the mechanical advantage of moving the vehicle, and the torque convertor won't slip as much, which can lead to overheating the transmission fluid.

I'd say this was more driver error than anything.

 

[jarussll4]

A lot of the vehicles with this Power Train (8 speed tranny with iforcemax and possibly just the 8 speed with Turbo too) are having teh same issue. I also think that the ones that are not is because they have not been reading the temps or paying attention to the tranny temp gauge (which I founf out it doe snot say much)
Here are the links to all the forums:


24-25 Tacomas https://www.tacoma4g.com/forum/thre...rheating-on-long-climbs-off-road.12606/page-8



25 4Runners: https://www.4runner6g.com/forum/thr...smission-overheating-on-climbs-off-road.4888/



24-25 Land Cruisers: https://www.landcruiserforum.com/threads/transmission-overheating-anyone-else.2108/

 

[jarussll4]

If you're driving up a steep incline that requires 4wd, and doing so at a slow speed, you should be in 4Lo. This will dramatically increase the mechanical advantage of moving the vehicle, and the torque convertor won't slip as much, which can lead to overheating the transmission fluid.

I'd say this was more driver error than anything.

4LO in a paved road would be very unsafe. Is not just off road that is happening is also happening on steep slow HWY climbs up mountains (For me Idylwid, CA and Desert to Julian ,CA). Paved twisty roads. I have had other 4x4's for over 30 years and had never had to angaged 4lo in a paved road. IT IS NOT DRIVER ERROR

 

[jarussll4]

If you're driving up a steep incline that requires 4wd, and doing so at a slow speed, you should be in 4Lo. This will dramatically increase the mechanical advantage of moving the vehicle, and the torque convertor won't slip as much, which can lead to overheating the transmission fluid.

I'd say this was more driver error than anything.

Maybe I just need to drive my wife's Prius, since she was driving her car up to Idylwild too and her tranny temps were below 200F by the end of the drive and mine was 240F. Both cars unloaded (actually hers had my 2 daughters)

 

[outdoorCO]

I have only 2000 miles on mine, but have been driving on a lot of mountain roads, on and off road from 5k-12k feet.

Did a road that climbed 3k over 6 miles the other day in high-4, transmission temp never budged from center once it warmed up.

Have also done 80mph up steep grades on I70 west of Denver, no issues.

 

[Gunnison]

If you're driving up a steep incline that requires 4wd, and doing so at a slow speed, you should be in 4Lo. This will dramatically increase the mechanical advantage of moving the vehicle, and the torque convertor won't slip as much, which can lead to overheating the transmission fluid.

I'd say this was more driver error than anything.

Yea I don't need to be driving that slow the whole way, I should be able to make it up a hill in 4H without having to switch back and forth between 4H and 4L every time I slow down for a rock

 

[AlanA]

You can install an aftermarket Tranny cooler on the 6th gen. This is on a 4th gen Tacoma but its very similar.

 

[jarussll4]

I have only 2000 miles on mine, but have been driving on a lot of mountain roads, on and off road from 5k-12k feet.

Did a road that climbed 3k over 6 miles the other day in high-4, transmission temp never budged from center once it warmed up.

Have also done 80mph up steep grades on I70 west of Denver, no issues.

Are you switching to Manual mode when in dirt raod climbs or you just leave it on Drive?
I noticed that if I switch to Manual and keep it reved up between 1st and 2nd it does fine, but I should not be doing that on paved HWY roads regardless of the climb or speeds.
When on high speeds or freeways mine is fine (it'll get up to 212F), but is the slow twisty paved climbs of slowing down and going between 15-45 and the constant climb on dirt roads also slowing down and speeding up (probably a torque converter issue)

 

[jarussll4]

You can install an aftermarket Tranny cooler on the 6th gen. This is on a 4th gen Tacoma but its very similar.

I should not have to add anything to a vehicle that is marketed as an offroad vehicle so that I could go hilly twisty roads that Priuses, Civics, Subarus and all other regular cars out there can do without even going over 190F on their tranny. Maybe if my vehicle had 200K miles, I would. But on a brand new vehicle?

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