Transmission overheating in 4HI when going uphill - Toyota's answer (or non-answer)

[Gfenza89]

Mine is smooth with the exception of the first cold shift or two… my BMW with the lauded ZF8 was the same way on a cold start. If your transmission is acting like that consistently then you have a problem.

Yeah I know…Toyota won’t even inspect the fluid for me, they sent an engineer FTS to the dealer and he said dropping the transmission would open a can of worms. What an absolute joke

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[Muckle]

Also having this issue. Both when towing a 1200lb trailer or just traveling forest roads while not towing anything and nothing in the bed.

I haven’t had it overheat and go into limp mode because I’ve stopped or just monitored it closely.

 

[BAQ717]

Also having this issue. Both when towing a 1200lb trailer or just traveling forest roads while not towing anything and nothing in the bed.

I haven’t had it overheat and go into limp mode because I’ve stopped or just monitored it closely.

No bueno. Too many people on here with the same issue for it to be an isolated issue. Hopefully everyone reports it to the dealer rather than just posting about it on here so Toyota is forced to take action.

 

[timetoeatpotatoes]

Also having this issue. Both when towing a 1200lb trailer or just traveling forest roads while not towing anything and nothing in the bed.

I haven’t had it overheat and go into limp mode because I’ve stopped or just monitored it closely.

somethings _gotta_ be going on.

 

[Lando]

Hmm, I’ve had zero issues with mine but I have not been in 4Hi going uphill. This is disconcerting if I need to be off road. I never had an issue with my old Chevys off road and I have climbed logging roads up mountains.

I would expect a TRD Off Road to be able to handle these situations as described without issue. Will be monitoring.

 

[JakeJoeBob]

Ive done some extensive up hill in hi with simliar loads and have not experienced this. However there is enough in this thread to suggest that something is going on.

Worth noting that the OTT tune will drop your transmission temps but I did my mountain overlanding trip before I got the tune. Not ideal to have to get a tune to fix the issue but just wanted to throw it out there as a possible solution.

 

[OGBugsy]

Does this happen with the hybrid as well?

 

[Bcphoto3]

Does this happen with the hybrid as well?

Yes. Mine is a Trailhunter.

 

[Madmez]

Yeah I know…Toyota won’t even inspect the fluid for me, they sent an engineer FTS to the dealer and he said dropping the transmission would open a can of worms. What an absolute joke

Mine was smooth up until 8k miles. It started making a clunking sound and had jerky shifts in low gears. I took it in, had a test drive with the tech but we couldn't replicate the issue. It's a bummer because the jerkines is random. He scanned it and checked the trans oil but said everything was fine. If it got worse, to bring it in.

 

[bsquaredMTB]

Update: I took the truck in today and they said that the connectors to the fans were loose causing them not to kick on to keep the engine cool enough. They plugged the in correctly and flushed the coolant in the truck. I have ABSOLUTELY NO clue if that's a reasonable thing or not. What do you guys think? Is this something they should check out during regular maintenance or is it possible that those plugs just happened to be loose?

 

[BAQ717]

I think there’s more to it than that. My guess is that Toyota will eventually need to issue a transmission logic update or update the radiator/integrated trans cooler. I have a hard time believing all these people have unplugged fans

 

[Texas Bob]

How is the technician supposed to duplicate the concern?
They can't fix what they can't find.

The technician's reply was that the truck's "transmission control history log" did not show a problem. That is how he/she is supposed to know what was going on. Apparently the data logging function is also broken, or else you got a technician who doesn't do the work but makes a denial of problem report anyway. OP: complain about BOTH problems to Toyota.

 

[GDobbins]

How it happened:

I was driving on a grated 2 lane wide dirt road in 4HI when the transmission overheated. I was loaded down with about 400lbs of gear and 2 people, 285/70r17 tires aired down to 20psi (2k miles on the truck.) I've done that road in a built and loaded down 4th gen 4runner and a F350 on 37s with a 3,000lb truck camper, and they both handled it no problem. I crossed an old Chevy Astro van that was coming downhill, and it made it. All this to say I expected my brand new TRD Off-Road Tacoma to be able to do this road no problem. I could see the transmission temp gauge start to go up as soon as we started going uphill, then the temp gradually climbed until it reached the red about halfway up the mountain at about 6k feet elevation. I lost power and it kind of felt like the truck stalled. I put in in 4lo and the transmission temp dropped a little below the red and stayed there consistently as we continued our way up. But 4LO was painfully slow for this type of road, and I was just itching to actually make some way up the mountain. So, I put it back into 4hi to see what would happen. Sure enough, within minutes the transmission temp was back up to red and the truck stalled. So I put back into 4lo and stayed there until we made it to the top.

The road it happened on:

I brought it to Toyota and this is what they said:

I asked the service advisor for his advice because the problem I had was real, and I expect that if it happened at 2k miles, chances are it'll happen again. His advice was to use my phone to record everything I can in real time and submit the evidence to Toyota. But the thing is I don't want to have to "prove" anything to Toyota, I just want the truck to work the way it's supposed to.

Has anyone else experienced this? What does the 4g community think? I'm thinking maybe I should have bought a 3rd gen...

I just experienced this on my first real test with my trailhunter. It was a very steep scramble and I got a transmission temp warning in 4HI. Let it cool and switched to 4LO and didn't have a problem. It wqs very steep though, too the point I thought it may have messed with the sensor.

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