Best gear to tow in?

I have a 2021 SR-5 6cyl. 4X4 access cab auto trans. with the Tow package, After reading a lot of posts here and my owners manual, I am confused about the best set up to tow a 3500 lb. boat. The manual only says that the ECT button can be used to tow, But some posts say to not drive in "D" but in "S" and then no higher than 4. I have been driving in D with the ECT on. Is this incorrect? My old Tundra did fine in "D" with the OD off button pushed, Is this the same as the ECT button? If I drive in "S-4" should the ECT button be on?? Very confused, Dealer had no concrete answer. Just -well,,Try this or Try this.. I tow a lot, mostly level terrain.

 

I tow in S5 and lower depending upon terrain. If it shifts in and out of 5th I drop down to S4.

 

In response to the thread title, the best gear to tow in is S4 + ECT. Your torque converter will lock up and you won’t have the gear hunting you would get in D and consequently your trans temps will be in a normal range for towing on flat land. (You also have manual control for down and up shifting). S4 locks out the OD gears (5&6) like an “OD off” button. ECT raises the shift points so it will hold gears longer on the upshifts.

Get yourself a device to monitor your trans temps. I use a Scangauge2 but there are other methods that work just as well.

 

Level terrain 3500# I would do S5 ECT on.

S4 is ideal for temps but gets quite noisy at highway speeds. I'd just be ready to bump it down to 4 whenever a change in grade arrives.

 

Thanks, for the info-Will change my shifting pattern ..I'm wondering-,,Just what does the ECT button do?? Why is it necessary when there is the "S" option? I do see it raises the RPMs. when in "D". I don't quite get it..

 

ECT, (electronically controlled transmission), is not “necessay” but, when turned on, changes the shift points (in D or S mode) to a higher rpm when the upshift occurs. In effect, hangs on to the gears a bit longer. Good for the towing application or just for zipping around in S mode (or D) without the towed load.

 

I may be wrong. But on your old tundra D with the OD off button pressed basically locks the transmission out of overdrive. I think 3rd gens have a six speed with 2 over drive gears(5th and 6th.) Using S allows you to select gears manually so you can stay out of overdrive. Its doing the same thing but a different way of achieving it basically.

 

If you read the manual it states to tow in S5 and lower for 3rd gens.

 

That’s not actually true. It says to use S5 when engine braking (while towing or not towing).

 

I'll have to pull out my manual and double check but I'm fairly certain in the towing section it states that towing is to be done in S5 and lower.

 

It’s not worded well and people constantly regurgitate that towing in D will damage your transmission.

 

that's for sure. I missed the part about engine braking performance. In my manual on page 186 it says the following

"Vehicles with an automatic transmission: To maintain engine braking efficiency and charging system performance when using engine braking, do not use the transmission in D. If in the S mode, the transmission shift range position must be in 5 or lower."

 

Just towed the boat 150 mi. and used S4 ECT on- average RPM 2500at 55 MPH./ On higher speeds (60MPH) used S5 ECT on- still was 2500 RPM I noticed no difference between the the two, But it was a lot different than "D" with the ECT on. That was 2100 RPM at 60 MPH with the tranny looking for shift points a lot. Mileage was a little lower in S mode compared to D. I think I'm going to to tow in S mode with ECT on from now on.