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I was reading through my Tundra manual and I noticed it said not to use cruise control when towing, I never use cc when in the city or in heavy traffic but there is much less fatigue when using cc when towing any distance.
The manual says not to do it for safety reasons but is there other reasons that I am not aware of?
 

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I have towed with my cruise control and noticed it will turn off when the rpms go above 3000 when it needs to downshift to make it up a hill at speed.
 

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Your drivetrain might not like it. It can lead to overheating, if not in "flat" terrain.
 

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I wanted to search this issue as well. over the weekend i towed a travel trailer and tried using the CC. It didnt seem to work very well. i think with the different throttle sensitivity and shift points that the tow/haul function provides, it messes with the CC logic or something. It seemed to not know how much throttle to apply and was shifting up and down somewhat erratically. i didn't really try it with tow/haul off since i was towing a sizeable trailer. Anyone else have some feedback here? I used to tow with my suburban and CC on regularly and didnt have issues. it helped keep my speed down which is hard for me :)
 

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Personally, I want 100% control of the vehicle, throttle, brakes, shifting when towing.
So, I never thought to use CC and never experienced this.
If it is important to take a break and rest your leg on a really long, flat trip, my suggestion would be to use tow/haul to get up to speed, then disengage it and engage the CC.
If you are in congestion or dealing with grades, CC shouldn't be on anyway.
And you don't need tow/haul mode on if you are already up to speed and will be going 65 mph for 2-3 hrs.
 

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Looks like everyone's comments above match my experiences as well. I tow a 9000 lb 5th wheel and on level roads while in 4th or 5th gear, the CC will function normally, but the second i hit any sort of incline and the truck needs to downshift, the cruise will shut off. I'm sure its just a safety feature Toyota has programmed into the ECO to prevent damage to the engine or drivetrain while the truck is operating under severe conditions.
 

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Looks like everyone's comments above match my experiences as well. I tow a 9000 lb 5th wheel and on level roads while in 4th or 5th gear, the CC will function normally, but the second i hit any sort of incline and the truck needs to downshift, the cruise will shut off. I'm sure its just a safety feature Toyota has programmed into the ECO to prevent damage to the engine or drivetrain while the truck is operating under severe conditions.
While damage to the vehicle powertrain and subsequent reduction of reliability is a concern to Toyota, my opinion is that both the owner manual recommendation and the automatic shut-off under severe conditions is to guide the owner into operating the vehicle with full mental attention. Towing at rated capacity requires more time to bring all that momentum to a safe condition in an emergency, and they don't want their convenience feature compromising the owner's reaction time; in other words, if a lot is at stake, keep your head fully in the game. BWDIK ;)
 

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I use it, but not a lot. Downshifting gets crazy on the slightest hill. I use tow/haul, and come down one on the gear selector. Fine across a lot of Kansas and Nebraska, as long as you aren’t going into too stiff of a headwind. Ha
 

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I use it a lot when towing my motorcycle trailer with a bike on it. No. It's not 5,000 lbs of payload.

But my true favorite is to just run the transmission in manual mode. Now THAT's the cat's pajamas.
 

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Looks like everyone's comments above match my experiences as well. I tow a 9000 lb 5th wheel and on level roads while in 4th or 5th gear, the CC will function normally, but the second i hit any sort of incline and the truck needs to downshift, the cruise will shut off. I'm sure its just a safety feature Toyota has programmed into the ECO to prevent damage to the engine or drivetrain while the truck is operating under severe conditions.
I am so curious as to how this makes any sense. As soon as the cruise control cuts out, I push the pedal down with my foot to maintain speed. It is less safe on a highway to be changing speeds constantly. The thought of holding down the pedal on a 2,000 mile trip is ludicrous. I am no less in control of the vehicle while the cruise control is engaged or not.
 

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I agree, my guess it's as a result of the "unexpected acceleration" from a few years ago.

Sent from my SM-N960U using Tapatalk
 

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I have had a 2011, 2016 and now 2021 Tundra and have towed with all of them. The 2011 was the best, we could load up an enclosed snowmobile trailer and travel across South Dakota on I-90 with the cruise set at 75. Worked like a champ and only complaint was the small gas tank then. Pulled all the river breaks without losing a beat. Downshifted automatically and flawlessly, loved.
Trade to a 2016 model and if it even saw a hill it kicked out of cruise :mad: pissed me off till no end when driving across this long state - 400 miles with minimal traffic.
Haven't tried the 2021 yet but expect the same. When I researched this back in 2016/17 someone passed along the info that the brain box had been updated to kick out for "safety reasons"
Every time I asked about it at the Toyota garage they just shrugged their shoulders and said "I don't know" or "Never heard about that issue before"
So I'm gueissing when I get my 2021 out on the big ol' long interstate that it'll kick out just like the 2016.

Has anyone heard of any sucessful reprogramming of the ECU to prevent this annoying problem?
 
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