The 2016/2017 six speed transmission tow haul issues are on the 14,001 pound through 19,500 pound chassis. Tow haul works properly on the 22K and heavier Ford Chassis.
Here is info from the IRV2 forum titled "Ford wont fix the 6speed problem".
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SSM 45876 - 2016-2017 F-53/F-59 - 6.8L Engine With GVWR 14,001 lb and through 19,500 lb - No transmission downshift on downhill In Tow Haul Mode
Some 2016-2017 F-53 Motorhome Chassis and F-59 Commercial Stripped Chassis vehicles
equipped with a 6.8L engine and a GVWR of 14,001 lb through 19,500 lb (4th digit of VIN is 4 or 5) may not downshift when going downhill when in Tow-Haul mode. Engineering is aware of this condition and is investigating. No repairs should be attempted at this time. Monitor OASIS for future updates.
I have a 2016 22K Ford Chassis and my tow haul feature works as designed.
Safe travels. JD
2016 Winnebago Sightseer 33C on a 2016 Ford F53 Chassis
2009 Saturn VUE
Buddy our Bichon Frise
JD & Kathy