Driving our Sunseeker up a 7% grade in the Big Horn Mountains.

[bayoubelle]

Originally Posted by BehindBars

Correct. Assuming we’re still talking about the Ford E450 6 speed, the transmission will override the request for 1st gear and drop to the lowest gear available with a safe RPM. If the vehicle speed then drops lower, and the lever is still in 1, the transmission will continue to downshift toward 1st as the RPM limiter will allow.

Thanks [emoji4]

[dcheatwood]

Tow haul will put you in the lower gear you need when you apply your brakes. Use it.

[n1acguy]

There is no such thing as an unloaded motorhome. Most are often very close to max weight. I use tow/haul all the time. I was sceptical at first that it didn't have a manual mode, but tow/haul works very well. The 6 speed is the same trans in all of the medium duty trucks. Ford's goal was to produce only 1 trans. They do use slightly different ratios depending on engine types (diesel or gas), so I was surprised that the E series didn't have a manual mode as the F series does with the same trans. I believe it's because Ford hasn't updated the dash electronics in the E series in many, many moons.
I can tell you that the 6 speed works so well in tow haul mode, that you'll never want to shut it off once you understand how it works and how to make it do what you want. In short, when descending a grade, you use light braking to get to the speed you want. As you do this the trans will select whatever gear it needs to be in to get it to hold that speed, then you stay completely off the brake, if you need a little more braking action use gentle braking to slow you more the truck will drop another gear.

It's a little slower to upshift when you want more speed however. Again, you have to coax it a little. Subtle action on the accelerator will make it upshift, but you give it too much, it might shift twice, and you only want 1 gear.

In theory you should just be able to leave it alone, but to get the full benefit of tow/haul you have to give it a little time to figure out what speed you want. If you're making abrupt changes it'll seem to stay in too low of a gear and not want to shift up.
Our weight with car in tow totals just under 18000. We descended from 6800' to about 1500' coming down from the Sequoias and down from 8000' on the west side of the Grand Staircase in N Arizona (that was steep). I stayed off the brakes most of the time on both descents. The only time I really used brakes was just to get to the speed I wanted long enough for the system to react, and then the truck did the rest.
I'm very impressed with the 6 speed electronic control. It could be quicker, but maybe it intentionally isn't to counter drivers who see-saw the accelerator.

Sorry so long.