Transmission over heat temp warning display...

Wife and I got up on Sunday morning out the door by 3am to go see the sunrise and try and get some pics of the moon.

I'm not sure how high the elevation was probably 2k feet give or take.

We were going up a forest service road pretty good incline and very rough so I had it in 4 wheel high.

About 2/3s the way up we got the warning, it said see owners manual.. I went ahead and kept going since were so close. Just as we got up to the top the warning went away.

I will get my reader out and see if it has anything stored. I've heard of problems when towing but this wasn't anything just driving so I'm a bit perplexed.

Should I call the dealer?

Some pics for your viewing pleasure...

 

Nice pics! Is your truck still under warranty? If so, I'd call the dealer. If not, maybe still call them but keep a close eye on things. That's odd it went off and you weren't hauling anything...

 

https://www.tundras.com/threads/2019-transmission-cooler-kit.60550/page-35#post-1869318

Yeah I'd be calling and asking why there isn't an external cooler, oh and get the fluid changed.

 

Yeah, time for a dealer inspection. You don't need to be towing to get high temps in these transmissions. I've gotten 235ish in the pan and 255 at the torque converter (measured on my Scan Gauge II) doing exactly what you just did.

The dealer should be able to scan the truck and report the specific fault. Ask them what temp is needed to kick off the alarm and what temp the transmission fluid can handle (and report back here). Wouldn't hurt to raise a stink about the lack of tranny cooler either....

 

Thanks guys I’m still under warranty only 11k on the OD.

I’ll give the dealer a call and report back.

 

4hi and slow speed is one of the easiest ways to overheat these trannys. Next time you find yourself crawling up anything throw it into 4lo.

 

I was wondering about that, I did try to get it in low on the way down but all it would do was beep and flash at me, so I left it in Hi

 

Not to ask a dumb question but you said it was beeping and flashing at you when you tried to put it in 4Lo. Did you have it in Neutral when you went from 4hi to 4lo?

This tread caught my eye as the last two trips i have been on i got a high temp trans warning climb steep hills so i need to change the fluid and have the dealership look at it to make sure the cooling system is working properly.

 

I was coming down and decided that lo would help in not having to brake too much. I did not read up on how to get it on low I tried stopping but did not try putting it in neutral. My wife was freaking out on the way down (good thing it was dark on the way up) so I didn't want her to think anything was wrong so I just left it in Hi all the way down. It did not overheat / warn me on the way down it was only on the way up.

 

Put it in neutral to switch to 4lo next time. Happy to hear you guys made it down safe. Picture are awesome of the moon!

 

Definitely get the dealer involved.

I think as more time goes on... we will see more temperature related transmission issues with these '19/'20 trucks and Toyota needs to pull their head out of their ass to address the issue.

I've got 3400 miles on my truck and Im already gathering the needed parts to put a trans cooler on it.

 

was this in drive the whole time?

I wonder if a lower gear would have helped.

 

Not going up, I was going down.
Might have..

 

Until Toyota initiates a service campaign (which could take several years, if ever), you are better off having a complete flush done on the trans and immediately installing a retro-fit trans cooler. Welcome to the club. MY2019+ Toyota trucks no longer have a cooler and many of us have already installed a kit so we can avoid the dreaded ATF overheat warning. Your truck should not have overheated in the conditions you described. 4L MIGHT have made a difference but shouldn't have been necessary.

 

I agree, my only thing is I’m not paying a penny. Ambient temps were in the 50s no towing simple drive up a service road, Toyota will own this problem.
I will be pulling the window sticker tonight and see if it had the cooler listed.

 

Just because you might lack an external cooler does not mean that would solve the issue if you repeated it with an external cooler. My 08 has an external cooler, and it still gets hot. The temperature will jump over 200 instantly if the torque converter unlocks, hell the other day in long drive through in 100deg weather the trans got to 240 just from sitting in gear parked. It sounds like the issue was you were going slow in high range so the converter had to slip a lot which inherently generates heat, regardless how many/what type of coolers you have. Low range makes everything happier. The reason the trans didn't get hot going down the hill was because it wasn't doing anything, even if you were in 1st gear it would've been locked up to use engine compression and not slipping like when it tries to put power down.

Also for future reference, when you go to neutral and switch to low range (or vice versa) it will take a few seconds to shift the transfercase, so be patient. It's not like high range where it'll slam into engagement.

 

I think you'll be waiting a long time if you wait for Toyota to do something about it. For me, the ~$400 I spent on the cooler kit was well worth saving thousands on a tow for my truck and my TT if my A/T overheated.

 

240F is not hot enough to trip the warning light. There's no way you got those temps in your pan either- I had a 2010 with the same cooler setup and even though the TC output temps would sometimes hit 240-250F, my pan temps always stayed stable at ~210F. I agree that there's no guarantee he would solve the problem but you can't sit here and tell me the cooler would make no difference. These trucks should NEVER *NEED* 4L unless you're pulling the space shuttle out of the grand canyon. Unloaded up a steep trail 4H should have done the job without the warning light.

Those who have experienced the warning light on MY2019+ Tundras have solved the issue by installing the cooler.

 

I will make another run up the mountain and go in lo this time and report back. I have an appointment with the dealer for next Monday. I am also going to hook up the software and see if there is anything stored.

 

If you have the tow package it will say engine/trans coolers. The older trucks that had the external coolers said Auxiliary Trans cooler. The omission of the one word is all they need to be legally covered. Your truck has the warmer/cooler puck, so the window sticker isn't going to help you. I am with you, I wish the truck had come with an external cooler, but the reality of it is that Toyota isn't obligated to do anything and they didn't lie or falsely advertise in anyway that would hold up in court.

 

One thing nobody has commented on is the light went off on the last 1/3 of the climb. I was still in hi and still climbing...?

 

I think I agree, it still won’t absolve them of a defect.

 

Instructions on how to use 4x4 are in visor

 

This is true. If there's a defect your warranty will have you covered for sure. I hope you can get it figured out without too much hassle.

 

There are a number of factors that could have caused this. More than likely your TC stator started to freewheel or you got going fast enough to actually lock up the TC clutch. There may also be thermal management strategies in the PCM that engage when the warning light hits to prevent damage to the A/T. PCM might have grabbed a lower gear and locked up the TC clutch once the warning light tripped. Unfortunately I can only speculate without seeing it first hand.

 

I was well schooled on hi, I really didn’t think or even try lo on the way up it just didn’t occur to me that I should be in lo.

On the way down I thoughtit might help in slowing the decline.

 

It was a very rough ride so to take it easy on the wife I never went over 10 mph and I’m almost positive I was 5-7mph all the way up.

 

I thought I heard of at least one faulty sensor causing the light to come on erroneously. Dealer should be able to identify it if that was the problem.

 

I would disagree on most points you stated. Obviously 240F is not enough to trigger the warning light, which I never said, I was merely pointing out that it's not hard to get the trans to get hot even WITH a cooler. Additionally, the pan temp was indeed at 240F along with the converter per my OBD2 reader; I agree the pan trails behind the converter, but that doesn't mean the pan can't get hot if the converter is just cooking.

And on your last point, I completely disagree with you that you should "NEVER NEED 4L". I have driven many trucks offroad, both recreationally and racing, and the surest way to overheat a transmission is to push it when you're not in a low enough gear and the torque converter is struggling to keep you moving. I can even attest to this in a not-offroad nor space shuttle towing experience a few weeks ago, where I was in stop and go traffic climbing I-70 in Colorado towing a 24ft trailer, and the trans was spiking from creeping forward 20ft every few minutes to the point I dropped it in low range as we sat there for an hour creeping along.

And to conclude my spiel, I do not think it's a bad idea to get an external cooler--I would--I'm saying if you're pushing your truck hard up a steep hill just chugging, just because you have a cooler does not NECESSARILY mean the issue is solved, it very well may be how OP was driving based on my personal experience. Of course, the flip side is we have no knowledge of what was actually climbing or how the truck was being used. I may very well be wrong on all points.

 

hey don’t blame my driving! Lol

To put the road into perspective.. I drove up in 10 years ago in a 2008 Mazda CX-7 4 banger FWD and 5 years ago in a beat up 98 Chevy 4x4 in rear wheel drive only..

there is no ffing way my driving or this road should over heat the tranny