My 2009 F250 tow/haul is turned on but engine braking (downshifting) is intermittent. I can’t determine a pattern as to when it does or does not engage. Are there conditions when it will engage? I haul 5,500 to 7,000 pounds of horses/trailer or trailer/hay. I spoke to dealer service and got some dismissive non-answer.

 

I think it's when it gains more than 5MPH with the accelerator pedal at zero, and I also think it will only shift down a maximum of two gears. I may be off on these, but I think I'm close.

From your owners manual: The Tow/Haul feature improves transmission operation when towing a trailer or a heavy load. All transmission gear ranges are available when using Tow/Haul. To activate Tow/Haul, press the button on the end of the gearshift lever. The TOW HAUL indicator light will illuminate in the instrument cluster. Tow/Haul delays upshifts to reduce frequency of transmission shifting. Tow/Haul also provides engine braking in all forward gears when the transmission is in the D (Overdrive) position; this engine braking will slow the vehicle and assist the driver in controlling the vehicle when descending a grade. Depending on driving conditions and load conditions, the transmission may downshift, slow the vehicle and control the vehicle speed when descending a hill, without the accelerator pedal being pressed. The amount of downshift braking provided will vary based upon the amount the brake pedal is depressed. To deactivate the Tow/Haul feature and return to normal driving mode, press the button on the end of the gearshift lever. The TOW HAUL light will no longer be illuminated. When you shut-off and restart the engine, the transmission will automatically return to normal D (Overdrive) mode (Tow/Haul OFF)