I was just reading another post when this issue came up. I was towing in the mountains this summer with an 8000 pound trailer give or take and the only way to make my truck down shift when climbing a hill at 50 mph and not loose speed was to manually put it in third gear. When I did this the truck pulled like a champ but like I said I had to initiate the shift myself. Has anyone else experienced this. My truck is a supercrew, max tow, 5.4 liter, 6-speed, with 3:73 rear gear ratio.

 

Were you in tow/haul mode? Then yes, the PCM will tend to defer downshifting.

With that load, I'd manually keep it out of O/D ....

 

Yes I was in tow/haul mode. It is a 2009 and no O/D off button is present anymore.

 

Yes, I am aware of that deficiency. I meant by using the gear selector ....

What happens if you don't engage tow/haul?

Sounds like you need some custom tuning - a tow tune, preferably a hi-octane one to make some decent torque gains ...

 

Sounds like it's not working right. I doubt you need a tune just to get it to give maximum performance. I know my 4.6L 3V will hit any gear I like just by pushing on the accelerator. It downshifts more readily in tow/haul mode but if you floor it in regular mode (tow/haul off) it will downshift quickly to the lowest gear that will not take it past redline. Then it really hauls ***!

Sounds like a warranty issue.

 

I pulled my motorcycle trailer to California (from Texas) last year with a friend's GMC 2500. In tow/haul mode, a tap of the brake pedal forces the transmission to downshift and hold the gear, providing instant engine braking.

I wish this was standard on every truck. It was definitely a nice feature that I used a lot in the mountains.

 

Are you sure about this? I have had several Super Duty trucks with this feature, and my 2010 F-150 now has it, too. None, including my 2010, perform the way you described. The tow/haul basically holds shifting to a higer rpm when accellerating, and then provides engine braking when braking. The harder you brake, the harder it engine-brakes. As for deferring downshifting, I find mine more sensitive to snag the next lower gear if I am losing power. Now, I have yet to pull my larger travel trailer, but even using the truck loaded up a bit, it performs the same as my past Super Duties. The only thing I really notice is it shifts to the final gear (O/D) gear alot quicker than my Super Duties would to O/D. In the Super Duty, I could run up to 62mph before they would hit O/D.