Upon buying my 2023 I almost immediately noticed how pessimistic the transmission is of the engine's ability to provide enough power at low RPM when using cruise control. If I'm in full control at 70mph, it'll stay in 5th gear on 3% grades or so, no problem. If cruise control is dictating things at 70mph, it downshifts at the first sign of any uphill. It's annoying enough that I don't use cruise control in slightly hilly areas--flats only. I am curious if trans behavior on cruise control was always like this, or if Toyota recalibrated stuff for 2020 to make it all work with the adaptive cruise control. Do 2010-2019's also exhibit this "downshift out of fifth on a 2% climb" behavior when the rig is totally stock?

Yup cruise control blows on this car with gear hunting and holding low gear too long. Doesn't matter the trim or year. Sucky sucky.

Our 2020 does this and is my biggest complaint with the truck. It's also the reason we had to remove the TRD Pro exhaust from the truck as the constant hunting induced massive and resonating cabin drone that was terrible on highway trips.

Even in early 2000s cars and trucks, this shifting behavior is not acceptable and is a well-known Toyota transmission logic tuning issue. When driving on the highway and without cruise control, the torque converter will unlock in 5th, thus allowing the truck to handle far steeper grades. With cruise control is engaged, the truck will downshift into 4th on almost any grade. Better yet, the thing will stay in 4th well past the grade and often times requires me to lightly stab the throttle to induce the upshift. What's really funny is when you hit just the right minor amount of grade and trans will go 4th-5th-4th-5th-4th-5th until you get out of the grade. My wife and kids use to think I was doing it myself and screwing with them.

How Toyota has not been able to remedy this absolutely awful shifting strategy and behavior is unacceptable.

If we're driving in hilly areas or areas with long grades, I often times just leave the truck 4th. It's a far more relaxed drive and at speeds below ~75mph running in 4th in areas such as these doesn't result in a measurable mpg impact.

Power really isn't the issue with this truck. If Toyota would have simply dropped in their 8 speed auto which has been on the market since 2008, they could have remedied this shifting issue a decade ago plus the truck would be much quicker and would get 15-20% better mpgs.

Toyota is an ultra conservative brand that is totally risk adverse and typically 5 to 10 years behind in technology.

Living in Western Washington and driving in the Cascades quite often and before I switched to 35s, I always switched to S4 when trying to use cruise control. It is less wear and tear on the drive train to drive-train to run the engine a few RPMs high and alleviate the gear hunting on the transmission.

No that I'm on 35s, have yet to regear, and have an "empty" weight around 5200 lbs - I'm in S4 all the time. I don't even bother with overdrive - it won't stay there more than a minute or two even on the I-5.

These transmissions hunt better than my English Springers and they are no slouches.

I don't seem to have this issue.. Mountain, Freeways at 80 etc. Only time I use the manual side is a steep downhill in 4wd(not bad enough for crawl) or I want to put rubber on the ground.

My 22 does this in the mountains between Arizona and California. Will a tune address this at all?

Yes, cruise control is always hunting, downshifting at the slightest incline.

When leaving Moab a few weeks ago, our rental TRD Pro downshifted to 3rd at 80mph.

Once I hit the Rockies, I stopped using cruise and it held gears much better.

I know that mine doesn't hunt at 80MPH w/ or w/o cruise on. I'm not sure at what combinations of speed/load it hunts but I know I've had it happen, usually at speeds lower than 80 and on inclines.

You must not live in an area that has long grades and/or steady wind. Our 2020 4Runner on Pro wheels, standard size AT tires, 1 to 4 passengers, and 0 to 100lbs in luggage routinely does it between 60mph and 85mph here in the Midwest where grades a minor but really long and winds ranging from 10mph to 20mph (often times much worse on the Plains).

This whole hunting issue could be largely addressed with just a couple lines of code in the TCM to tell the damn trans to unlock the torque converter in 5th on mild grades rather than going for 4th. TCM and ECU see a change in vacuum in 5th when going up a minor incline and assumes you're getting ready to climb a mountain. LOL. So dumb that they can't fix this and it's been this way since the 5th gen was introduced 100 years before Christ himself.

Agreed on my area lacking long inclines. On a trip to Nashville with a full load I tended to not use cruise so that part of the experiment went unfulfilled. When going up mountains my MO was to simply gas it to maintain speed. The downshifts occurred and stayed as long as necessary. With cruise on I'm pretty sure it would have hunted. Realistically I think it's the nature of the beast. Just the limits of the engine/transmission/gearing/weight/programming revealing themselves. A 4.7/4.6 V8 and 6sp trans would solve things! In the future if I try cruise under the same conditions I may also try DS mode on the inclines if hunting occurs.

Not wanting to beat a dead horse.....but....yes.....it will downshift on hills with CC active.

I have found around 65 on CC to be the most frustrating as not only will it downshift it will accelerate past the 65 up the hill and keep the throttle down as you crest the hill. It is easy to be pushing 72 right over the top of the hill with a 65 CC set. It can get aggressive at times!

Like others have said, I will put my foot on the pedal and manually give it just a bit more to prevent the downshift then just release at the top or I will hit cancel and take over then resume.