The motor will rev MORE when you downshift. For instance, if I am at 4,000 rpm in 3rd gear, it's going to spin faster DOWNSHIFTING into 2nd.

OP is trying to get his truck to shift up (to 4th gear in my example).

 

Both tow/haul and sport modes hold rpm high when coasting downhill. And you have to get on the throttle for a second or two before tranny upshifts. I find that annoying, but it's a normal trait. I only towed once (in tow/haul mode), and on a steep downhill, I also notice the tranny just wouldn't upshift even at around 4K rpm. But I think that's by design, since it's trying to engine-brake as much as possible. The problem is a low-compression smallish engine trying to slow down thousands of lbs is almost useless for that. Anyway, you have 2 options if not happy with that. The first (which I did), is to use the brakes to slow down and bring rpm down to maybe 3K, then release and repeat. The second is you could upshift manually (manual mode) to the next higher gear (lower rpm)... but you'd have to use the brakes more.

 

Thanks for the replies. I understand how the cruise down shifting operates.
I did try to click up the gears to try to get an upshift.
I did not take it out of tow/haul.
I've been trailering for 12 years, last 3 trucks were Tundras.

The wrench symbol, unable to upshift without going to into neutral, signals that this is not operator error 🤔🤔

Now hopefully the dealer will not tell me that they cannot duplicate problem.

My intention was to see if others had this occurrence so I can be better informed when I take it in.

 

Keep in mind that the dealer will not be able to duplicate the problem unless they drive it under the same conditions and with the same trailer like you experienced. Best thing is to have a service manager ride along with you so you can duplicate it for them.

 

Cross your fingers. lol. Hopefully the wrench set a code the dealer can see. My guess, there is a flash they will perform to the electronics.

 

See update