Tow haul mode

antman78 wrote:
The MH T/H setting controls the fuel injection timing. When the setting is set to "n", the fuel injection timing is optimized for normal driving conditions. This means that the engine will get better fuel economy and performance when it is not hauling a load. So, unless you are hauling a load, it is best to keep the MH T/H setting set to "n" for the best performance and fuel efficiency.

Better when not heavily loaded. Unless you have a way to undock the house part of the motor home from the chassis it's always heavily loaded.