Overheating Transmission

[WookieBait]

Not sure how many times this needs to be said, but 4L / manually shifting will solve any and all of these overheating issues. This vehicle regardless of how people feel, is not designed to do really any off roading in 4H.

It's all cool though, if you want to smoke your transmission off road for not wanting to use 4L and leaving it in 4H/D, buy something else. I'm not sure why this is even a conversation, takes nearly zero effort.

Using 4l only delayed the issue for me and made traveling off-road annoyingly slow. also would happen to me on city streets in hilly areas, I'm not stopping to put my car in 4lo and out when driving on normal roads. No other full time 4wd vehicle has required such work around but, again it only delays the problem for me, will still overheat.

People on this forum get way too invested in defending this piece of shit transmission. It shouldn't overheat, full stop it's a problem. maybe they should of put better cooling in.

 

[WookieBait]

Curious why we have 4Lo… and the NPS is lying?

NPS errs on the side of caution because if they say it's a "easy dirt road" you get morons in cx5 rentals getting stuck blocking the road, great sand dunes np is notorious for this..

Parson Branch Road | Off-Road Trail Maps, Difficulty, Trail Status | onX Offroad

Explore the Parson Branch Road off-road trail with detailed trail maps, elevation, distance, trail difficulty, and trail photos.

www.onxmaps.com

"4WD is not needed at all for the route and is friendly for stock-height vehicles."

 

[rysn]

Not sure how many times this needs to be said, but 4L / manually shifting will solve any and all of these overheating issues. This vehicle regardless of how people feel, is not designed to do really any off roading in 4H.

It's all cool though, if you want to smoke your transmission off road for not wanting to use 4L and leaving it in 4H/D, buy something else. I'm not sure why this is even a conversation, takes nearly zero effort.

Doesn’t solve the issue actually. It’s also not a viable solution on paved roads in town or in stop go traffic on the freeway when in grades.

 

[Slippers]

Doesn’t solve the issue actually. It’s also not a viable solution on paved roads in town or in stop go traffic on the freeway when in grades.

Just looking for clarification: Are you having overheating issues driving on pavement, around town and in traffic?

 

[phxdsrtrat]

I'm going to chime in here as an old man who has been off roading for over 40 years in Arizona where sometimes the temperatures are around 115F - 120F. We also have an extremely steep grade on I-17 Northbound to get out of the valley where many vehicles towing heavy loads tend to overheat. So, not only coming from point of experience but living in an area here temperatures have a factor.

Up until my LC 250 I have never owned a vehicle that required the use of 4 LO to keep the transmission from heating up. I have always manually shifted at slow speeds while off road so I can't speak to that point.

When towing my trailer (2500 lbs) up and out of the valley the transmission does not heat up. So this is not an issue for me.

Last summer I did the trail to the Harquahala summit in my LC 250. A nice, easy to moderate difficulty trail depending on road conditions. I've done this trail a few times before in 2 other vehicles. It was a typical AZ summer day with a temperature around 110F. Even with manual shifting in HI 4 I saw the transmission temperature rise. It got close to the red line about halfway up so I did pull over and let things cool down.

For me, living in AZ I have installed a auxiliary transmission cooler on almost every off road vehicle I own. It's just good insurance out here to make your transmission last longer. So, I did this with the LC. A fairly involved project but not outside my skill set.

I did the same trail 2 weeks ago. Same style driving, 4 HI with manual shifting. Same temperature of 110F. Same dry road conditions.

The transmission temperature started climbing. It leveled off at about 3/4th the length of the gauge and stayed there through the climb. So, the transmission cooler had a positive impact. I forgot my ODB II scan tool so I couldn't get the exact temperature.

For me, because of our high temps here I consider this acceptable. However, from what I am reading people are seeing this in lower temperature climates. I don't think adding a transmission cooler when you don't live in these extreme conditions is an acceptable solution simply because you are using 4 HI on a dirt or gravel road with a slight incline. I believe Toyota needs to look at this and figure out a resolution for what is one of their flagship offroad products. The Tacoma and 4Runner also have reputations that should be protected.

-Curtiss

 

[WookieBait]

Just looking for clarification: Are you having overheating issues driving on pavement, around town and in traffic?

Not who you responded to, but YES. Mine overheated driving around on paved roads at lower speads in hilly neighborhoods (Think downtown SLC/SF). I think most people that don't offroad or live in the extremes of dealing with low speed hilly areas will ever experience any issues. Putting it in 4lo and using tow mode, or manual shifting does not resolve the issue, it only delays it. So if you aren't pulling constant grade putting in 4lo or manual shifting might seem like it resolve it, but it doesnt, you just didn't do it long enough. You can read of people having the same problem with the same transmission in the 4runner/tacoma as well.

 

[sweet5ltr]

I've driven multiple days, 8-hours straight in 4L in Moab, 90° ambient conditions, I also live in one of the most mountainous / remote regions in America. I am not saying this (4L/M) is a solution, just a requirement for the OEM setup until Toyota inevitably has an OTA update for the PCM/TCM or TSB where there is a reflash for these systems at the dealer. Right now, it is required, and I don't really care because it doesn't bother me but it seems to bother many other people for the inconvenience. 4H does not provide any of the throttle control of 4L and you can just feel the transmission suffering on inclines at low speed - I only run in 4H in areas without hills or climbs.

I've built numerous drag cars with very high stall converters, driven on the street in Florida, they had the largest auxillary transmission cooler I could physically fit and an additional electric fan dedicated to that cooler. I'm not new to these issues, but I'm not doing any of this until the warranty period has expired, which won't be until 125,000-miles.

If you take it upon yourself to install a transmission cooler, just be prepared for a warranty denial claim for anything regarding the OEM transmission - they will blame the install and potential ingress of foreign material, debris etc etc etc.

That's the situation we are dealing with at the moment. Toyota demands this platform be in 4L (read the manual), and until enough transmissions are cooked, they won't make an effort to change it. As more people begin to off road these platforms, we will see solutions either from Toyota or the aftermarket.

So, options are to either sell it or do whatever you can to NOT heat the fluid. The moment you start cooking trans fluid, the longevity of that transmission is heavily compromised.

 

[izzysanchez]

You dont need 4Lo or transfer case for lower gears. Toyota puts it in all land cruisers to add unnecessary weight and reduce gas mileage. They don’t know what they are doing and cant design a 4WD to save their life. They are clueless and have wasted all that weight since the first FJ40 in 1958.

Joking aside (in case i need to point that out), your transmission should not overheat. However if you know how an automatic engages, there is a time for 4Lo to get better control of your power train. No shame to join a good 4WD class for those who want to know.

 

[GR8Santini]

Again I was on a trail....Hell its not even a trail it's a dang Road that has been there since 1838. Its all maintained by the forest service. OnXOffRoad rates it a 2 (Easy), and that is being very liberal. You do not even need 4WD to complete this. It links Cades Cove to the Tail of the Dragon. If my transmission was overheating on this trail, then there is no hope for this vehicle to do anything of real value off road. Again 4LO or manual shifting is just making excuses for a vehicle you are now invested in and won't come to terms that Toyota is no longer the purveyors of quality and reliability. I'm sure there are a lot of new 4Runner and Tacoma owners who also will agree with me.

Going down a paved road you don’t have issue - right?
On a trail if you leave a AWD vehicle in ‘D’ it will constantly search for optimal gear out of the 8spd with load, grade, traction, etc - that’s going too raise temps.

Select manual & pick an appropriate gear for the trail & tranny will be happy. If that’s too difficult sell the LC for something more numb & mindless to drive.

 

[izzysanchez]

Again I was on a trail....Hell its not even a trail it's a dang Road that has been there since 1838. Its all maintained by the forest service. OnXOffRoad rates it a 2 (Easy), and that is being very liberal. You do not even need 4WD to complete this. It links Cades Cove to the Tail of the Dragon. If my transmission was overheating on this trail, then there is no hope for this vehicle to do anything of real value off road. Again 4LO or manual shifting is just making excuses for a vehicle you are now invested in and won't come to terms that Toyota is no longer the purveyors of quality and reliability. I'm sure there are a lot of new 4Runner and Tacoma owners who also will agree with me.

So you didnt read my whole post, did you. I said regardless the transmission should not overheat, thats is not acceptable. The only time i had a land cruisers transmission over heat was on an 80 series, on 4 low, tough trails, and was doing too much two foot driving and got the fluid too hot. Otherwise, its not acceptable for that to happen.

 

[Matthew@LC250Mods]

The transmission tuning is largely the cause of this. The torque converter is tuned to stay unlocked at all times in 4H, to make things less jerky, but that creates a lot of heat especially at low speeds and when climbing hills, etc.

I would highly recommend the Mishimoto Transmission Cooler. One of our members on here was the first to install one and confirmed it fits with very, very little modification. This was originally designed for the Tacoma but is 93.75% plug & play on the LC250 and tremendously helps avoid the trans overheat warning.

 

[Matthew@LC250Mods]

Thanks very much for the recommendation, I'll look into that. At this point the transmission is just a final straw to a series of disappointments since ownership. I am likely getting rid of this as soon as my registration and title are received (Still on temp tags)

Dang, sorry to hear that! I hope the experience turns around, or if not, you can find a replacement that checks all the boxes!

 

[GR8Santini]

Take a breath. Fact is if you own a LC250 you have moved up to an All Wheel Drive vehicle now. It is not a Part Time 4WD system like you’ve owned before. Much different. Any off-road adventure providing a lot of slippage will raise transmission temperatures. There are suggestions in your owners manual on how to prevent the slippage - as any wheel slipping is creating heat in a AWD system that you as the owner should try to prevent. If you’re going up a grade over walking speed you have wheels slipping. Find a specific Manual gear in 4Hi that works for you on the trail, or go to 4Lo. If you leave it in Drive in 4Hi & slip you’ll have a Hibachi for a tranny sooner or later. Or blame it on the vehicle.
Please don’t do any posts on towing temps..

 

[sweet5ltr]

The transmission tuning is largely the cause of this. The torque converter is tuned to stay unlocked at all times in 4H, to make things less jerky, but that creates a lot of heat especially at low speeds and when climbing hills, etc.

I would highly recommend the Mishimoto Transmission Cooler. One of our members on here was the first to install one and confirmed it fits with very, very little modification. This was originally designed for the Tacoma but is 93.75% plug & play on the LC250 and tremendously helps avoid the trans overheat warning.

I 100% agree with this, but Toyota corporate won't and will deny any warranty related claim for the transmission after this point. They will point to the install for potentially allowing XYZ contamination into the transmission.

I'm not sure if we could have a Toyota dealer install this under the guise of 'towing' to maintain the factory warranty (I wouldn't want them touching mine, unless it was a very competent service department). Doing that, along with adding an additional electric, thermostatically controlled fan, it would solve all of these issues.

 

[MSINAL]

The transmission tuning is largely the cause of this. The torque converter is tuned to stay unlocked at all times in 4H, to make things less jerky, but that creates a lot of heat especially at low speeds and when climbing hills, etc.

I would highly recommend the Mishimoto Transmission Cooler. One of our members on here was the first to install one and confirmed it fits with very, very little modification. This was originally designed for the Tacoma but is 93.75% plug & play on the LC250 and tremendously helps avoid the trans overheat warning.

I agree the xmission is causing itself to overheat because of the torque converter slip. What makes little sense is why it doesnt stop using the electric motor and allow torque converter to lock up when trans temp starts running out of control. Or hold lower gears when temp is starting to rise until it cools down. Of course deactivating the electric motor would de-rate the powertrain but thats obviously better than cooking the trans fluid.
Design flaw that needs a remedy asap.

Im going to go hug my 6speed manual trans now.

 

[QuickSilver66]

Out of curiosity, would driving in H4 but using MTS and selecting "dirt" help prevent the overheating issue?

 

[ultane]

And yes I will be unloading this shitbox as soon as I can.

That’s obviously the right decision for you. I hope you find something that satisfies you, and checks all the boxes.

 

[Matthew@LC250Mods]

To my knowledge, all of the settings still keep the TQ unlocked. It's possible Toyota comes out with a new trans flash in the future that has altered TQ tuning to help mitigate this. Then again, they may state that off road use counts as abuse and blame any potential failures on the abuse rather than the poor tuning choice.

 

[Bad1975]

Edited: I'm sure most here understand we don't just a traditional torque convertor only setup, instead on the hybrid it's the K0 clutch (Motor Generator Unit) between the Engine which has a clutch between the flywheel and K0 unit and Transmissions torque convertor, which switches between all electric, all ICE, combo and regen, it's a little more complicated than programming a simple TC lockup into the TCM.

Toyota needs to look into the programming for the K0 clutch operation, as its obviously got some programming refinements to be made, in addition they may need to update what conditions cause the electric fans to come on to aide in Transmission and K0 clutch cooling.

I've not received the temp warning ever, but I have had it 3/4 the way up on the gauge (stopped and began cooling after manual gear shifting and selecting the proper gear), cooling fans never kicked on as the ICE temp was fine. I've since fitted an aux cooler and have had nothing above halfway on the gauge since.

 

[MSINAL]

While trying to find diagram of the torque transfer i found this interesting analysis. Answers many questions we have regarding abrupt shifting behavior.

Toyota L580F Transmission Guide: Reliability, Problems, Repair Costs

The L580F is where Toyota’s modern truck-hybrid transmission story gets complicated in ways older Toyota truck automatics never were.

transmissionaudit.com

I can find the 10spd hybrid L4A0E.L4A0F diagram and it shows engine->K0->TC->transmission
Cant find this for LC250 L580F, i thought it was the same as 10spd layout.
Here is the source of 10spd layout. Appears to be same for 8spd but cant confirm.

Toyota Hybrid - Transmissions line-up

List of hybrid transmissions of Toyota and Lexus vehicles

toyota-club.net