Earlier today, I was driving home my newly purchased 2003 V8 4 Runner with 108k miles on it that is replacing my 3rd Gen that a kind soul ran a red light and totaled. The drive home is has some hills that are fairly steep but nothing that is longer than a couple hundred yards at most. About half way home, where there is the most hills, (this was from Salt Lake City UT to St George UT) near Beaver UT, my A/T oil Temp light came on. I was letting it cruise at around 83 to 84 up the hills with an outside temp of about 80 degrees. After the light came on, I backed off to about 78 and the light soon after went off. Does this seem normal for it to get that hot? From what i read needs get over 300 degrees to have the light come on. It didn't feel any different and was shifting fine. I also completed the drive without the light coming back on but was more careful not to let it cruise up hills. The previous owner of 8 years only used the runner for around town and said he didn't ever or make trips in it and had never had the light come on. Is there anything I can do to keep temps down such as an extra cooler or drain some fluid and refill a couple times?

Seems kinda strange, I would do a drain and fill in the trans, see what comes out and add new fluid back per the factory instructions.

Unless you're pulling something rather heavy at those speeds it's very odd, even in this heat. I vacation in Wyoming in the summer and make the trip from Texas/Oklahoma in the brutal heat doing 80-85 along highways. Some hilly and some not. I've never had an issue. I think many here can say the same.

Not normal at all. I run 80+ mph in hot weather all the time with a roof rack and mine has never come on.

The first suspect is the fluid level, although a cruise control not working correctly could contribute to hotter running by increasing the amount of time the torque converter is unlocked, but I still wouldn't expect a light to come on.

2003 should have a dip stick to check fluid level. It probably has a notch for both hot and cold checks and I would do both to make sure.

With the light having come on, though, you're probably going to want to get some new fluid in there anyway.

Thanks for the responses, I thought it seemed very odd as well.

I checked the fluid just barely with it being hot. The level was right at the lower notch for hot, I'll check it again later tonight when its colder to see what it reads.

Is it okay to add straight through the dipstick to bring it in between those levels? (or drain and fill) It was also fairly red still so i'm wondering if the fluid was changed.

If ATF WS wasn't use could this cause heat issues?

Something is definitely not right…. As other recommended I would start by changing trasm. fluid… maybe someone put wrong type of fluid.

Just FYI with condition you have described transmission temp in my truck would be around 150-160;

Possibly a sensor issue? I'd get a temperature gun and monitor the pan temps.

If it is actually high, you may want to check the lines to and from the cooler and the trans cooler itself for plugging.

Something just isn't right. The v8 also has an external tranny cooler which keeps things cooler. I am wondering if a line is plugged or someone changed the fluid with the wrong fluid and affecting the torque converter lockup.

If you can find someone with a TIS Techstream use that to see the actually tranny temps. Maybe it is just a simple sensor issue..

The thing that struck me as the oddest was that it went back off when after 5 minutes or so. I never pulled over and only backed off a couple of miles. I'm guessing it was either the sensor went wacky. Or I know the fluid was "topped off" by a Toyota dealership about 2k miles ago. I'm wondering if they dislodged something that temporarily plugged a line.

My next course of action will be to get an IR thermometer and check the pan after it warms up. The current ambient temperature is right around 100 degrees.