Pulling a trailer and tow/haul mode?

Discussion in 'Towing & Trailer Tech' started by theflatlander, Apr 20, 2014.

  1. theflatlander

    theflatlander New Member

    I have a 02 gmc sierra. I have to replace the tow/haul button and shift lever which is a common problem that I am sure you guys all know of.

    It got me thinking about using the tow/haul mode more. I have pulled a lot of trailers and my last truck was a older manual. None of this fancy mode stuff.

    Is it necessary to use tow/haul mode? What exactly does tow/haul mode do? I have always heard never pull a trailer with your with the over drive option on. Is that always true or is there a weight ratio that my truck can pull without having to worry about using overdrive or tow haul mode? The most I plan on pulling is a 87 alumcraft competitor 16.5ft with a 50hp tiller motor. I dont know the exact weight of everything on that trailer.

    looking for any tips and information.


    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    The Purpose of the Tow/Haul Mode is to:
    ***Reduce the Frequency and Improve the predictability of Transmission shifts when pulling a Heavy Trailer or a Large or Heavy load.
    ***Provide the same solid shift feel when pulling a heavy trailer or a large or heavy load as when the vehicle is unloaded.
    ***Improve Control of Vehicle Speed while Requiring Less Throttle Pedal activity when pulling a Heavy Trailer or a Large or Heavy load.

    Automatic Transmission Equipped Vehicles are provided with a button at the end of the shift lever which when pressed enables Tow/Haul.
    ***When the button is pressed, the Tow/Haul has been selected. Tow/haul may be turned off by pressing the button again, at which time the indicator light on the instrument panel will turn off.
    ***The Vehicle will automatically turn off Tow/Haul every time it is started.
    ***Tow/Haul is designed to be Most Effective when the Vehicle and Trailer Combined Weight is at least 75% of the Vehicle’s Gross Combined Weight Rating (GCWR).

    Tow/Haul Is Most Useful Under The Following Driving Conditions:
    ***When pulling a heavy trailer or a large or heavy load through rolling terrain.
    ***When pulling a heavy trailer or a large or heavy load in stop and go traffic.
    ***When pulling a heavy trailer or a large or heavy load in busy parking lots where improved low speed control of the vehicle is desired.

    ***Operating the Vehicle in Tow/Haul when Lightly loaded or with No Trailer at all will Not Cause Damage.
    ***However, there is No Benefit to the Selection of Tow/Haul when the Vehicle is unloaded.
    ***Such a Selection when unloaded may Result in Unpleasant Engine and Transmission Driving characteristics and Reduced Fuel Economy.
    ***Tow/Haul is Recommended only when pulling a Heavy Trailer or a Large or Heavy Load.

    Edit.....as far as Towing in Over-Drive, IMO it Depends on the Tow Vehicle, it also Depends on the Weight of what's being Towed, and last where/what kind of Terrain your Towing.....Freeway/Highway, and/or up Hills/Mountains etc...

    When Towing my Boat, I Never Tow in OD.....with the Engine, Gears, and Size Tires I'm Running on my Truck....I Stay in 3rd, for me, I would rather Burn a Few Extra Gallons of Fuel, than Burn-up my Transmission.

    Here's one more piece of information and its regarding The Tow/Haul Not Working, which is Most likely due to the Wire/Wires that go down the Shifter, down to the base of the Steering Column, and down at the Base is where the Break of the Wire/Wires will be, below is a Video that shows how to repair the Wires for the Tow/Haul Button,

    Last edited: Apr 21, 2014
  3. theflatlander

    theflatlander New Member

    I have posted this on another forum also and keep getting different suggestions on what settings/gears to use when pulling. My boat isnt extremely heavy since it isnt a glass boat, but with the hills we have around most of our lake country it would make more sense to pull in third gear.

    I really dont see the reason why not to pull in fourth gear/OD as long as my rpms arent constantly changing and my truck is shifting every couple minutes.

    I guess I should of really put in my topic why shouldn't I pull in fourth gear/OD?
  4. doublecardan

    doublecardan Member

    I am assuming that you have the 5.3 with the 4l60e combo. The reason most people would recommend not towing in overdrive is because with this tranny, there are only two od clutch plates and with the constant unlocking of the torque converter it would generate quite a bit of heat. Most of this is dissipated through the tranny external cooler.
  5. WorthFlorida

    WorthFlorida Rockstar 4 Years 100 Posts

    The bottom line of tow/haul mode is the transmission shifts to the next gear at a higher RPM. This places less strain on the clutches, bearing & gears inside the engine/trans/differential, thereby every thing should run cooler. I usually use tow/haul mode when going from start to about 45-50 then you can go back to regular mode provided that your're on level ground and how heavy of a load you're pulling. If you're towing at max load limit of the truck and allot of steep hills, stay in tow mode. I use tow mode when I i have a load in the back of the pickup at or over the max carrying weight. A pallet of fresh cut (with damp soil) St Augustine sod weights about 2000 lbs.

    My 2012 Silverado 5.3L 6-speed auto, 3.42 locker rear end has plenty of power and when I pull a Murano on a tow dolly I can easily cruise on I-95 with tow mode turned off. On local roads I can easily pull this load not in tow mode but I will put it in tow mode to keep the transmission happy. The truck has a DCI display with a transmission temperature reading. I'm pulling 4000 lbs and the truck has a max rate of 7500 lbs pull weight. I'm sure you can tell if your truck is straining when towing by how many times the trans wants to down shift. Using the tow mode really depends on your fell of the truck. FYI, in tow mode around 60+ MPH the trans does shift into 6 (OD) gear.
  6. bsmntcritr

    bsmntcritr Member

    When towing in low speeds (traffic), I generally hold the truck in T\H mode as the the shift point higher between gear changes. I only need my right foot to initiate a lower if needed quickly. On the freeway I set the trans in manual mode and lock out 6th gear. The current RV is in the 7500 to 8000 lbs area and is too heavy for for 6th gear to be of much use. I don't use T\H on the freeway for the simple reason of engine breaking. When the trans downshifts because I have hit the brakes while on a down slope, the engine revs will climb well beyond 4500 rpm. There isn't any slow down rather the opposite. The the engine can't develop any back-pressure - twin 3" exhaust pipes will do that for you! The DIC is always set to display trans mission temps when I tow.

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