Tow Haul Mode really necessary?

I’m a Canadian down in Florida the last few months. 2023 Tundra with 4800 lb trailer. I cruise at 60 mph, on cruise control to maintain the speed. Florida has these frequent very slight hills, from a small stream valley or when the main highway climbs up a bit to pass over a secondary road. On level roads I see 1650 RPM and about 22 Litres per 100 km (sorry that’s in Canadian units). That’s in 8th gear.

With tow haul engaged, a slight climb causes the mileage to drop to about 30 Litres per 100 km where the transmission then drops down to 7th. Mileage settles about 35 Litres per 100 km in the slight climb. The spouse keeps complaining about the frequent downshifts, and certainly it is annoying, and the number seems excessive

With tow haul off, maybe I shouldn’t, but instead I see that the transmission stays in 8th gear as the mileage drops, and it settles about the same 35 Litres per 100 km going up the slight hill. No downshifts at all. Maybe one downshift in 20 miles versus one per mile in tow haul. Seems so much easier on the transmission. I could use S7 but then I’m needlessly doing 2000 or 2100 RPM on the flat areas.

Do I need to have tow haul on to protect the engine? Or can I not use it and save the transmission from so very many down shifts?

I see the manual says tow haul has some steering effects, and allows for engine assist for braking. It also says to use it for a trailer. However there is no caution about long term engine strain if not. I’m not talking about jack rabbit starts, or a requirement for quick engine response. Just cruising.

Am I putting extra strain on the engine/transmission that affects long term?

Stan

 

Not a 3rd gen owner.

Can you not just lock the truck in 7rh gear?

I own 2, 2nd gens. I just lock them in 4th. No down shifts and minimal mpg losses from not being in the highest gear.

I'd rather have higher RPMs overall vs having to deal with multiple down and upshifts.

 

@Pstan do you have an obd reader and that is why you can see what gear the truck is cruising in? Not sure how you are determining what gear it's in. Also just set the cruise and let the truck do it's thing. Of the 7 modern truck I've personally owned this truck by far shifts smoother than all of them so surprised the spouse can even notice. Also if you have the JBL sound system shut the fake engine noise off and that will quiet things down considerably Also if you keep it in tow or tow + it will hold gears longer and not shift up and down so much too. That or start taking the train places....

 

Or maybe time to trade er in for a new model???..,...,..........the spouse

 

I'd use it. It's not the engine you're worried about. It's about cutting down on the constant shifting back and forth and the t.c. . . Granted, these trucks don't do alot of shifting unless it's pretty hilly but I'd use it. . Not worth a couple m.p.g.s. . Just my .02

 

No offence, but I doubt you are smarter than a computer. When you tow, put it in tow haul. It's engineered that way. Further to that, you can ignore it, leave it shut off, but when the tranny fries out of it, don't come back and start a thread on " Shitty Transmissions "

 

I agree with trade in...... This is one of the smoothest shifting transmissions. If the shifting bothers her get her in a BMW M5 with a double clutch trans and hit it hard, then she will notice what a quick hard hit between shifts really is...

 

This. You can experiment a little and see how your fuel economy changes when locked in 7th. I see 1 - maybe 2 - mpg hit when I lock it down a gear, but much less shifting. Overall, it makes for a more comfortable tow.

Personally, I rarely ever use Cruise Control when towing. The truck can’t anticipate hills like you can, it can only react to load once you are on the climb. Giving it a little more pedal before the climb or at the base helps maintain speed up the climb. The cruise control sees a decrease in speed and compensates with a downshift and heavier throttle to get back up to speed. If you drive proactively rather than reactively, you can often times keep the truck from downshifting AND get better fuel economy. I get much better fuel economy when I’m actually piloting the vehicle than letting th le computer pretend it’s driving.

 

With that said^, I can use CC, but cancel it as I'm going down hill, then I manual step on the gas to maintain, plus increase speed a bit. Once I'm close to cresting the hill and know I'm close to the peak, I'll click the CC back on.

Regardless the rig, towing a trailer and using CC, will not be a "set it and forget it" situation. The trucks computer wants to maintain the exact speed you set it for. This will cost you mpg's and you will feel multiple up and down shifts.

You will have to experiment to see what works best for your truck and trailer.

For example:

My 2nd gen gets 14 mpg empty while letting the computer doing the shifting .

I hook my 10k 5th wheel RV to the truck and travel 800 miles I get 9.8 mpg. I do the gear selections. I use cruise when I know it's flat and traffic allows it.

I lock the transmission into 4th as a max gear and top out at 70 mph. I slip into 5th on the random downhill stretch that I know has no sharp curves. I know you have more gears, but the principle applies.

Like said above, you will have to use your own experience to " feel" what gear the truck likes to tow your trailer in.

Us that tow a lot all have OBD computers that monitor the functions of what is going on with the engine and transmission.

I use a ScanGauge2. I have one all my vehicles. It's nice to know the actual temps vs a very, very rough indication from the dash gauges.

 

If you are in “D” then push the shifter over to the left so you are in “S” then the gear you are in will appear on the information screen. At least that’s how it is in the SR5. It shows in the little screen between the 2 analog gauges. As you manually shift it will shows the changes.

 

Adding that I love Tow/Haul mode and use it extensively driving in the mountains. Really nice for engine braking downhill and excellent response for steep hills. And always when towing. I figure if they put it on truck with the towing package then I should use it. It’s not necessary, but if it’s there you might as well take advantage of it.

 

Tow haul just changes shift points and accelerator mapping to help you feel more comfortable towing, plus what you mentioned. There really isn’t any protection. I find your comment about downshifting strange. In my experience tow haul holds gears longer than normal mode. Maybe the reason for the discrepancy from my experience is cruise control?

 

I agree.

In defense of the trailer industry, trailer tires are rated for a max speed of 65 mph. Toyota has tuned the trucks to take advantage of this speed.

You don't need top gear when cruising that slow.

Even though we get the best mpg at the top gear empty, it is not the case while towing.

I found it hard to wrap my head around the fact that the truck does not lose that much mpg running at higher RPMs yet the same miles per hour.

The engine is just running more efficient and cooler with hi engine speeds.

Get yourself a engine monitor and verify for yourself. Anyone that tows really should know what is going on with drive the drive train.

 

I've hauled a lot of trailers through the years. Everything from motorcycles to backhoes. IMHO Florida is not a place where the tow mode is needed. It only puts unnecessary strain of the tranny to be shifting as much as you say it does and leave the cruise off.

 

No automatic Trans should ever be used in Overdrive to tow. Tow/Haul limits the trans to 7th gear which is the strongest in this Tundras 10 speed being a 1:1 ratio (power is going straight thru the trans not using any gearing. Puting a load on a planetary gear set (what’s used to gear up for OD) will overheat and burn up the small star gears. 3rd Gen Tacomas are famous for burning these. Either use Tow/Haul (which also changes the fuel injector mapping between port and direct injectors) or lock it to 7th as the highest gear in Sport mode. Honestly I think you’ll want all the extra benefits of Tow/Haul mode (injectors, shift points, torque converter, steering pressure, ABS and stability control)

 

I learned this lesson on a Holiday Weekend in the middle of Nowhere. Most trailer tires are rated for 65mph. I had a double blowout on my boat trailer. Dog and wife in the truck - 100 degrees outside - many miles from a tire shop.

Maxxis does sell a trailer tire with slightly higher MPH rating - I bought 8 of them the next Monday.

Disclaimer - I don't recommend trailering at high speeds. But I live in Texas and the posted speed limit is 75mph. You can't drive 64mph across the open expanse of Texas.

 

Buy Goodyear endurance trailer tires. US made load E rated, with an 86or87 speed rating. Many of the quality trailers are starting to put these on from the factory. Awesome tires.

 

Just a point of clarification, most decent trailer tires are 81
max

not that I would ever go that fast but they are rated that fast

 

Your comment about overdrive is absolutely not true. All the planetaries rotate. The 1:1 ratio just means they all spin at the same speed. The high overdrive gears usually can’t be used because the wheel torque necessary to accelerate with a trailer is great than what the engine times the high gear ratio can produce so a downshift happens. It’s actually better for heat to keep transmission rotation speed low. If you tow up a steep grade in low gear at 5000 rpm, the ATF will heat up more quickly vs. taking the same grade in a higher gear and lower rotation speed like 2500 rpm.

Usually the clutches will let go first before a physical gear is damaged. Is there a thread on the Taco forums for these problems?

 

Oh yeah I know that part. It just shows what gear is the max gear it will go into when in sport shifting. The transmission will still down shift if you put your foot down but the screen will still show s8. Was curious how the op knew exactly what gear he was in....like he said he was in 8th gear not that he had shifted to S8 and was holding it there. Was curious if there was a Banks reader or something in the mix.

 

Hello Group. Original poster here. Many thanks for so many replies

Koditten: Yes I can use S7, that will give me about 2000 or 2100 rpm at 60 mph and prevent the Tx from going into 8th, which otherwise the Tx would do in D with tow haul, on level ish surfaces. Frankly I don't want the increased revolutions on the engine if I can avoid it. And I can with D, Toyota allows D with tow haul, and this limits the revolutions.

Teab: I just know the rpm vs speed that give me 7 8 and 9th gears in D. 10th I've never been into, thats like 75 mph downhill

Nomoredomestics: You said "just use it, its about cutting down on the shifing back and forth". Thats exactly my problem, using tow haul causes looooots of very short downshifts, for every small incline. Not true with tow haul off, for my florida driving.

To the group in general: I wasn't concerned about fuel economy with or without tow haul. It was all about the constant downshifting that doesnt occur with tow haul off. Again, very slight inclines I'm referring to, not reasonable hills. So my inquiry solely relates to transmission strain.

blenton: I try do exactly as you say, cruise off, and that works for most of the time, but its tedious to keep feathering the throttle the right amount at the right time, to prevent all these downshifts. And too may times it still downshifts on me anyway.

Koditten: "experiment and see what works best" you say. that is what I'm doing, but interested the the forum's opinion on transmissin strain if tow/haul not used on slight hills

22what: re tow haul you say "Its not necessary". Do you know that? Its not necessary to prevent transmission strain?

xc_tc: small hills causes downfhifts in tow haul, for me. with or without CC. Why is that "strange to You"?

Racer57: you say "IMHO florida is not a place where tow mode is needed". That is exactly what I was hpoing an expert would say. But until then, the manual says to use it......

PNW: Tow Haul lets me get to at least 8th gear, not just to 7th. Perhaps what you say is true for tow+ haul+?

XC-TC: Wow, quite the diagrams, my brain struggles to take it all in gotta study that.

thanks to all

Stan

 

Also figure out what the spouse doesn't like, if its hearing the engine when the truck downshifts as I said look into disabling the the fake engine noise using carista if you have the JBL sound system. If you have the JBL system and turn that off you won't hardly hear the engine in the cab.

 

This thread reminds me of a license plate I saw. Keep the fish. Throw the old lady back.

 

Hi Stan,
I only said that as a response that it is completely possible to tow all kinds of stuff without using the Tow/Haul mode. @Eurodriver even hauls a gooseneck with his SR model (no T/H Modes). I personally wouldn’t do it, as I feel they added the towing package to protect the truck from overuse. Myself growing up in the 80’s watching my old man tow trailers with a ‘64 Ford 1/2 ton 3 on a tree, a 77’ Oldsmobile station wagon, and ‘79 Dodge van, he pulled shit all over with those “ancient” vehicles and we only over heated half the time . So as a society we made it this far doing all that kind of stuff. But the modern vehicles have made towing so much better so why not just use it? I am wondering if you should get it checked out - my experience and nearly everyone who has towed with the trucks is that they do it very well, so your experience is an outlier.

 

We're basically saying the same thing. Yes, the planetaries are all spinning when the trans is in 7th, 1:1, but they are all locked and spinning at the same rotational speed as the input and output shafts ( ie, the Sun, Ring, and Carrier/Planetaries are all locked together ). Thx for the great reference charts. Yes, you can search the 3rd Gen section of Tacomas.com for many instances of burned up transmissions which resulted from towing in OD. ( 5th or 6th ).

 

Stan, it appears you are asking the wrong question - or least looking for the answer for one question the replace the answer of another question.

Do you NEED tow haul mode? Not necessarily, but it was designed to improve the towing experience and keep temperatures and vehicle vitals in check, letting the computer know that you are hauling extra weight as opposed to driving around empty. Will the vehicle function without using it? Yes. But you need to be more cognizant of how the vehicle is operating. The downshifting isn't from the Tow Haul mode - it's from your truck needing to make more horsepower to overcome the the drag of your truck and trailer climbing hills. You can either slow down a few MPH as you climb, or downshift and maintain speed.

If the real problem is the MRS being unhappy with the truck downshifting on hills, you have two or three options: lock it in to a lower gear and/or don't use cruise control on the hills. You honestly shouldn't be using CC while towing on grades or in traffic anyways - it's hard on the vehicle, makes for an uncomfortable towing experience, and lures people into complacency when they should, instead, be extra vigilant while pulling a trailer. I say that DESPISING the idea of telling other people what they should do, so please take it as an adamant suggestion.

CC is fine for a a couple of minutes on the flats or in wide open low traffic situations on ideal weather days and road conditions to move your leg off the accelerator for a minute. But honestly, if needing to push the pedal down more often when towing in the hills is an inconvenience or difficulty or a hardship, perhaps you should re-evaluate your capacity and ability to pilot a vehicle and trailer. Yes, I know that sounds like a jerk thing to say, but pulling a trailer requires more attention and effort than cruising down an empty stretch of highway or even driving an empty vehicle through moderate traffic. I routinely pull trailers on a 200 mile round trip where the longest flat stretch is maybe 3 miles and the longest straight road is maybe 5 miles. The rest is winding hills, roads cut in the side of mountains, and 1500 ft of elevation change from one end to the other with probably twice that elevation change from going up and down hills. Except the last 10 miles, there are all of 5 passings zones. I fully expect to be modulating the throttle the other 180 miles, as do the other drivers on the road, if I want to maintain a decent consistent speed. Else, the truck is jack rabbiting half the trip, my fuel economy goes in to the toilet, and I'm ready to lay down on the side of the road to escape the vomit coaster.

The third option really isn't an option, but you can pay more attention to what the road is doing and what the vehicle needs to be doing down the road. I say it's not really optional because it should be self-evident why doing as much ought to be considered required behavior instead of an optional action.

I'll end my rant, but your truck is designed to pull a trailer very well. That doesn't discount you from needing to pay attention and adjust your own driving habits, too.

 

This is a very good post!

 

Depends on the ol’ lady. Mine saw a Tundra in the dealer showroom while getting an oil change on her Camry. She texted me a pic and said. “We should trade your Tacoma for this”

Im picking up my 24 Blueprint Platinum TRD Saturday! I love that woman

 

I did though require the dealer to disable fake engine sound upon delivery.