2012 Tundra Tow/Haul Switch

[Neal H.]

I tow a 2015 Vibe 27BHS with a 2012 5.7L Tundra 4X4. The owners manual for the truck says to use the Tow/Haul switch when towing heavy loads. However some people tell me to take it off Tow/Haul on Interstates or other high speed roads. Can someone tell me the best way to use this option? Thank you.

[4mula1fan]

Not sure how tow mode works on a Tundra, but on my Titan tow mode extends shift points in the lower gears to get you rolling easier. It does nothing in the upper gears. I have to turn off O/D manually...I would say to use it if the manual says to.

[awellis3]

Originally Posted by Neal H.

Can someone tell me the best way to use this option? Thank you.

Yes. When towing, engage Tow/Haul and leave it alone.
Unlike older Tundras with overdrive (like my 2005), the Tow/Haul "alerts" the transmissions computer to analyze its inputs using a different set of computations. This results in altering up- and downshifts. It also allows the tranny to go into its highest gear, even when towing. Also, you'll notice the tranny responds to braking by downshifting more quickly.
Set it and forget it. That transmission knows more about its job than we do.

[acadianbob]

I'd say your trailer is a heavy load. The Tow/Haul mode is there for performance and drivetrain longevity reasons. You should use it.

[djeirlessr]

I have a 2011 Tundra and use tow/haul mode when pulling my FW. Just for the heck of it I put it in tow/haul mode without pulling the FW just to see if it made any difference in fuel mileage. It had no effect I still got 17.5 mpg. When pulling around 10,000# to Florida I averaged 9.5 to 10.2 mpg. I guess because I was pulling down hill all the way. You should use tow/haul mode when pulling heavy loads.

[Edmund]

Have been towing @ 7000-7500 lbs for five years with a 2010 Tundra. Always use the tow-haul. It was put there for a reason.

[SilverArrowPro]

Biggest thing the tow haul mode does is help the transmission from over heating.

[bluewoo]

Use T/H mode that's why the engineers put it there.

[SilverArrowPro]

engineers... that's funny.. you are talking about people who put spark plugs where you can't reach them, or filters in locations where you have to remove a transmission and separate the housing to get to it... engineers.. that's funny stuff.

[Maron]

I tow a 7500+ Rockwood 8329SS w a 2013 Tundra and use the tow/haul in and around city towing but I shut it off on the highway. My measurements indicate a 2, to 2.5 mpg improvement without the tow/haul on the interstates.
The reason that is important is I make 2 1800 mile tows from Chicago to Phoenix annually and with a 26 gallon tank that reduces the stops and shortens the time.
I just read that they are going to 36 gallon tanks in new models & I wish I had that capacity.

[Maron]

And djeirlessr isn't that far off on his down hill comment. Going West to east last Spring my mpg was up from 8.5 to 10.2. Had to have been a prevailing tailwind.

[chipmy]

Like Maron's post, at times when were on highways that are relatively flat I have T/H off. When off interstates or in hilly environments I turn T/H on. I have experimented with the T/H on and off during a trip and I do see a reduction in my MPG with it on. So that's why I only use it when in situations that would require it. 2006 Toyota Tundra Quad cab with a Hybrid Shamrock 19' wich is about 4500lbs.

[wuffwuff]

Heat is not your engine/trans friend. Use the T/H any time you tow, unless your pulling a utility trailer with you Cub Cadet. Any kind of weight will cause the trans of over heat if running at high rpm straining to keep the pace in the wrong gear. Think back over the years .... you probably had a friend that tried to pull a camper behind a car, and only got halfway on their trip and the trans over headed and had to be replaced. The engine will overheat also trying to pull in the wrong gear. Like some of the above posts, the Trans Control Module will shift according to towing conditions. Watch the Tachometer and your see little change in rpm's at highway speeds.

[bluewoo]

Originally Posted by SilverArrowPro

engineers... that's funny.. you are talking about people who put spark plugs where you can't reach them, or filters in locations where you have to remove a transmission and separate the housing to get to it... engineers.. that's funny stuff.

What the hell did you buy? LOL
Something did ok on my Toyota so I wont complain, But you do have a point with engineers!

An engineer is a practitioner of engineering, concerned with applying scientific knowledge, mathematics, and ingenuity to develop solutions for technical, societal and commercial problems.

[Maron]

Wuff Wuff, the 2013 Tundra Limited has a transmission temperature gauge mounted on the dash and if I'm not mistaken something special to do with extra cooling for the transmission. In my journeys across the hot southwest I've never seen a temperature change when using the t/h function or not using it. So while I understand extra heat is not Good on a transmission performance I don't think the T/h button influences that.

[Ditchooker]

tow/haul does not change any physical parameters, (ie line pressures) it is just throttle and shift pattern modifications. The unit that comes in the Tundra is very good for staying cool. I am running a Torque app with actual temps, and it stays in lock up very well, (keeping temps down) and the factory cooling is also very good. pushing hard with my old trailer (7k lbs) I never got over 208 degrees.