2012 Toyota Tundra 5.7 SR5 Towing Package

Thanks everyone for your comments about towhaul on our new Tundra. We are looking forward to our first trip in the new truck in 19 days. We are going to Topsail Hill for our 10th year and we can not wait. We will have to be careful on our payload, we cant take as much in the Tundra as we did in our dually.

mastercraft1995 wrote:
Put it in Tow/Haul mode and leave it.

X2. I have tried S5 in my 2007 for a while when I first got it, and trust me, tow haul in "D" is the only way to go, and really the only way it works correctly, and I live around plenty of mountains in Utah, Nevada. The computer knows best!!

Put it in Tow/Haul mode and leave it.

According to Toyota, tow mode operates the same way in every Model year 2007-13.
All the PDF's are the same for each year.
The tow mode light will come on when pressed in "S" mode, but it does nothing.
Once you read the PDF you will see why it is impossible for tow mode to work in "S"mode.
Every feature in tow mode is tied to the computer selecting the proper gear, controlling how the throttle operates,etc.
"S"mode by definition is a full manual mode. There is nothing wrong with using "S" mode and certain situations it is the better choice,but for most people tow modes works just fine in most situations as long as you don't exceed the parameters for it to operate correctly.

To the OP, 5th and 6th gear are essentially overdrive gears. My suggestion is that you place your transmission in S mode, click it to 5th gear and put it in tow/haul mode. Perhaps S mode locked out tow/haul in earlier trucks, but I know my 2010 still allowed use of tow/haul in S mode.

By putting it in 5th gear it keeps the trans from shifting into 6th gear, which is a very high ratio gear. This prevents your trans from constantly shifting between 5th and 6th gear. That keeps your trans heat down, keeps wear and tear on the drivetrain down and helps improve your fuel economy.

When approaching a steeper incline I like to manually downshift before the hill and get my rpm's up prior to the hill.

Goldstalker wrote:
I agree use tow/haul and lock out 6th gear.

Tow/haul mode is disabled in "S" mode.
From the shop manual,"
The conditions required for tow/haul control to operate are as follows:
- Shift position: D position (Tow/haul control does not operate in the S position)."

The owners manual does a poor job of explaining how tow/haul mode works, therefore there is a lot of misinformation on what tow/haul mode does and the parameters in which in works best.
Most complaints about tow mode allowing the tranny to shift into one of the overdrive gears is the result of people towing at to fast of a speed.Once you get much above 55MPH, you have exceeded the parameters of the programming.
here are a few other things that tow mode does.
" Throttle Control
Throttle control changes the relationship between the accelerator pedal depression angle and the throttle
valve opening angle.

During tow/haul control, the throttle valve
opening is increased by throttle control. As a
result, acceleration performance is ensured."
"Shift Schedule Control
The shift schedule control changes the upshift and downshift schedules during tow/haul control.

For the upshift schedule, the upshift timing is changed to higher vehicle speeds, enhancing the use of
lower gears. As a result, drivability is ensured."
"For the downshift schedule, the downshift timing is change to a wider throttle valve opening angle,
enhancing the use of higher gears. As a result, the frequency of gear changes is reduced, allowing optimal
shift quality."
"Wide Open Throttle Shift Timing Control
Due to wide open throttle shift timing control, upshift timing is delayed to make use of high engine power
when the accelerator pedal is fully opened.

Wide open throttle shift control operates in 1st, 2nd and 3rd during tow/haul control."
"Powertrain Cooperative Control
Through cooperative control with ETCS-i (Electronic Throttle Control System-intelligent) and ESA
(Electronic Spark Advance), and electronic control of the engagement and release speed of the clutch and
brake hydraulic pressures, excellent response and shift shock reduction have been achieved."
There is a lot more information, including diagrams that explain in detail what I have put in quotes.
I am willing to email the PDF's to some of you that would like them.
I also have the PDF's for nearly every component of the Tundra.
I have one the first Tundras made and help run a 20,000+ member Tundra forum.

I generally do not use Tow/Haul when towing. I would be interested to know more precise detail about what T/H actually does. Not much information available except that it changes shift points and the manual says you will get slightly poorer MPG in T/H.

In T/H the transmission will try to utilize 6th which at least in Colorado it cannot hold with even a slight incline. So it will unlock the torque converter which feels like a slight shift, and if that is not enough it will downshift to 5th. It might also lock or unlock the torque converter multiple times in 5th or even shift to 4th. For this reason I will generally drive with the selector in S5. The torque converter will stay locked up and there is not all the hunting around by the transmission. BTW even if you have T/H selected it is deactivated if you use S shift mode.

For engine braking on hill decent, I also don't find T/H aggressive enough for lower gear selection. I use S mode and select the gear that gives the necessary engine braking.

I agree use tow/haul and lock out 6th gear.

Turn on tow/haul and put shifter in 4th or 5th. On long or steeper inclines use 4th-for short or lower inclines use 5th.

I leave tow/haul on all the time when towing as it changes the shift points and other things for some sort of an advantage, though I'm not sure what that is. I figure the software is smarter than me so I keep it on. It will still shift in hills as you describe. To be honest, I've never noticed much difference with it on or off except it shifts a bit different.