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  1. #1

    Default Tow Haul Mode Question

    After research on different sites including a search of the GM Powertrain site I have a tech question I cant find an answer for and Im hoping someone else knows the answer or where I can find it.
    My question concerns 07 and up 6spd automatic transmissions (6l80) myc.

    When activating the Tow Haul Mode transmission shift points are changed, in addition to this what other changes happen?
    Does the timing advance?

  2. #2


    I was always under the impression that tow/haul mode changed shift points and pressure but did nothing to the engine, but I don't have any sources to confirm or deny this.

  3. #3


    I don't have all of the changes, but here are some:
    - the shift points change (as you noted)
    - the tranny will auto down shift when going down a steep hill and the brake is used.
    - there is a hold function when stopped going up a hill (as at a stop light), preventing truck from rolling back,
    - when lane change signal is used the normal 3 flashes will change to 6.

    I'll post more if I find any

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  4. #4


    All of the above on my 2011, if the trailer is hitched or not.
    I am a American solder, I am a member of the finest fight force on earth, I am the bump in the night. I will defend the United states of American Against all enemies both foreign and domestic. Repent now all those who would do my nation and it's people harm; For when we come it will be too late.

    2011 GMC Sierra SLE, Z71 with 5.3 l and max tow/haul package

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