Tacoma Automatically Shut Off with AT Oil Temp Warning

2021 TRD OR DC LB. I was off roading recently and my tacoma shut off twice over two hours due to an high AT Oil temp warning. In both cases I was in 4L with the rear diff locked. On the first occasion I had gotten stuck for 15 minutes (high centered and flexed out), gotten unstuck and then hit an incline and receaded slightly, i.e. hit a bump and did not power over it. The tone sounded, the high AT oil temp warning showed and the vehicle shut off. I waited a minute and tried restarting and it started right up and drove fine thereafter. When it was safe to do so, I sat for 30 minutes to let it cool down.

An hour later, I had been off roading for 40 minutes. I was in 4L mostly with the diff unlocked. I came to a rougher section, and locked the diff in order to get unstuck. I left it locked for 10 minutes. I eventually climbed a steep, deeply rutted section. As I was negotiating a stump and bucking a little, the high AT warning sounded and showed, the vehicle sounded like it was stalling, and then a low oil pressure warning briefly showed before the vehicle shut off. In this case, I was at 30'. I tried restarting the vehicle after 3 minutes. It had trouble starting, but eventually turned over. I got up the climb and then found an easy exit - moving out of 4L and into 4H.

I've had no issues since in driving home, driving to/from work (60 miles). I wheel in 4L a lot and have never previously experienced this issue. It certainly was not an intense enough trail that I would expect the transmission oil should really be hot. I've heard mention of bad sensors, a bad fuel pump, or possibly the sealed transmission might not have been filled properly by the factory.

What do you guys think is going on? Thanks in advance for your help and ideas.

 

An OBD Bluetooth scanner connected to an app isn’t a bad idea to monitor temps in situations like this. Even if the temps really isn’t your problem, you’ll be able to keep an eye on various things.

 

Interesting, are you saying I could actively track the temp or just plug in while the issue is occurring to check the temperature? Do you have a recommended device?

 

I have an ultra gauge that works great for watching pan and torque converter temps. Plugs into OBD port and stays there.

 

Active view

 

Not mine, but this is an scan gauge II setup in a third gen. This one is showing transmission pan temp, torque converter temp, coolant temp, and current gear. I have one in my 2.5 gen, love it and have battery voltage showing instead of gear.