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Towed my Jayco trailer(22FB, 4365lbs dry) from Austin to Blanco St Park. Roads smooth, rolling hills, light traffic. This is a Dual Cab, tow package with 4.6L engine. Pulled easy although it did a lot of shifting on the hills. Gas mileage was 12mpg as opposed to pulling the same trailer with a 4Runner that got around 9.5mpg. This was also with the tow/haul engaged. Needless to say, I'm pretty pleased with the truck. I may have done a little better mileage with the larger engine, but my towing time is a small percentage of my total driving time so I went for around town economy.

Here's a question for you experienced trailer guys. I'm still fuzzy on the "S" usage on the shifter. My understanding of it is that it is a standard shift without the clutch and you select which gear you want using the +/- control on the shifter. The digital display only goes to 4 but it's a 6 speed trannie. Does that mean it changes operation to a 4 speed?Exactly how is this control used, and, is it used with the tow/haul or independently?
 

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The "S" mode lets you select the highest gear you would like to drive. It defaults to 4th gear as that gear will usually prevent an overspeed of the transmission. It is useful while driving in heavy traffic, descending hills while towing. The truck will still start in 1st gear from a dead stop, but only upshift to the gear showing in the "S" display. If you shift into S and hold the lever forward to +, it will shift into 6th, bypassing 5th. The Tow/Haul mode is disabled in the "S" mode, which will limit automatic downshifting when slowing down.

There have been many discussions on the topic. If you search you should be able to find the transmission pdf file that explains it a little better.
 

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The first tow and maybe even the second was not what I expected (lots of tranny confussion) but once the tranny programs itself for towing, towing in auto "D" mode is amazing. I only use "S" mode for going down step grades to keep the heat off of the brake rotors. Trust me I called and complained about my tranny on the first tow and the dealer said "leave it in "D" for a couple tows and it will learn what you want and need and all the shift points will smooth out". The dealer was correct and this tranny pulls perfectly in "D" mode and stays in the right gear for the right amount of time. By the way, my trailer weighs 8200 pounds from certified truck scales.
 
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