I have a 09XLT 5.4 6 speed with 3.55 rear end. We just purchased a 26 ft travel trailer. It weighs about 5.5 k lbs. The truck pulls it very well. One odd thing, when pulling on flat land, the truck will hunt between 5th and 6 th gear. I am in tow/haul mode and figured that would keep it out of 6th gear.

I guess the transmission knows what it is doing, I just thought it odd that it will shift into 6th with that much weight and in tow/haul mode.

 

As far as I know tow haul mode only increases the rpm shift point, basically dragging out the shifts longer to so when the truck shifts it's not at the bottom of the next gear.

 

That sounds logical... I just hate when it constantly going back and forth between 5th and 6th..... Probably when I put some more weight in the trailer it will not be so inclined to go into 6th...

 

How often does it shift gears, several times in a mile, or once every couple miles?

Heat deteriorates transmissions (well, almost anything mechanical). Unlocked torque convector and frequent gear shifting increases trans heat. Overdrive is fine (and you have 2 of them) as long as it maintains the gear for a while.

Read your owners manual about the tow haul mode. You might invest in a trans temp gauge to see the effects of your shift patterns.

 

Don't all 09 trucks have the temp guage on the dash now? My FX4 does.

 

Just a comment....

I wonder if the trucks computer will 'learn' your pulling the trailer while in tow/haul mode after a while?

I only pull a 3500# trailer, and found the same thing the first few times - constantly hunting for the right gear - seems to have calmed down a little now.

I've also found in tow/haul mode, I've had to adjust how and when I use the throttle on hills - I kind of had to 'learn' how to give the computer my input at the right time.

 

What speed are you pulling at and is it flat ground? Also, cruise control off or on?

My trailer is about the same weight at 24 ft and pulls solid in 6th gear (tow/haul mode) all day long though I have the 3.73 rear.

 

the frequent shifting seems much worse with the cruise on.it's kind of annoying driving all day without cruise.and my 09 has 3.73,s 7500 gvw trailer

 

Unless your pulling on absolutely flat ground, I wouldn't tow with the cruise control on. The cruise control makes abrupt adjustments which causes the tranny to shift a lot more than manually feathering the gas pedal. Seems to be a downside with the 6-speed tranny and tow/haul mode as compared to my old setup where I just towed in 3rd.