i towed for the first time with my o5 psd trailer and machine weighed 11,000 lb im not sure about the tow haul mode seemed to work good but on desending some steep hills it would kick down and tach would go to like 4,000 rpm for quite a while and then finally upshift is this how it is suppose to work ?? it did tow good though maybe im just not use to the new tranny

 

I've had my for A year now and yes thats normal, just don't let go over 4200 red line.

 

That down shift is like a tranny break...saves on the truck breaks...wonderfull when towing.

 

Depending on the length and % of grade, I think I'd keep to below 3000rpm and suppliment with wheel braking.

That's like running second? gear to 60mph. ???

I don't have the automatic transmission. What gear does your transmission drop to when you're using the trans brake?

 

I have a toy hauler that is typically loaded to around 10,000 lb. Going down some of the 8% grades in T/H mode the tranny will hold back the truck pretty well. The engine will rev to around 3800 or 3900 or so sometimes when trying to hold that load.

Generally it will not be that high for lesser grades.

You can always press the brake pedel a bit harder or add some trailer brake, but keep in mind that as you press the brakes and let up and then press them again, at some point the tranny will shift to a lower gear to add more tranny/engine braking.

If the engine gets to a point where it is revving more than you are comfortable with, simply toggle the T/H mode button and kick it out of T/H mode. At that point you'll be freewheeling though and wheeee, you can pick up speed pretty darn quick.

As F250Wheels says, just don't let it rev over 4200 RPM. You could let the trailer push it to 3900 RPM all day long though and not see a problem - this motor spins well for a diesel