Have Toyota Questions? Ask a Mechanic for Answers ASAP
Thank you for allowing me to help you with this concern today and am sorry to hear that this is happening. I will have to ask you a few questions so that I can get a better understanding as to what may be going on with your Tundra.
The Haul mode should not work in the S mode due to the fact that you, the driver are basically performing the same task. Here is a quick video on the Tow Haul feature and it keeps the truck in lower gears longer.
When you shift to the "S" Sequential position, you the driver are selecting the gear you want via the shifter and not the computer. Does this make sense?