No, it does not have an effect at low speeds.
I've never seen either a 4R70W nor a C6 that would do that. Every one of them that I've driven start and stay in 2 when the shifter is in 2. I can't explain how you had the only two that don't do that.
No, it is not. Go read it again. Ford recommends towing in overdrive UNLESS it is frequently shifting in and out of overdrive.
When the shifter is in 1 there is a hydraulic circuit that forces the torque converter clutch to UNLOCK. It is impossible for the torque converter clutch to lock in manual 1. If you are in automatic first gear it can lock if the throttle is open at least 75%.

 

MK, I think we are saying the same thing,
sorry if I explained. wrong , Ford RECOMMENDS locking out of overdrive if you're experiencing frequent down shifts while towing heavy loads.

 

So does common sense.

 

Years ago my father and I towed his 24' Bayliner from CA to Vancouver island with his iirc 05' 2wd F-250 with the 5.4 not sure what auto trans, it had but plenty of power. When it was his turn to drive he would leave it in od, I explained that it's hard on the transmission shifting up and down constantly creating extra heat.
He understood what I was explaining, but in his way of thinking OD meant extra power or stronger pulling power if you will. After that experience I can understand how people can think that way if they are not tow or truck savvy.

RIP Dad..

 

I don't think you remember correctly. An '05 2wd F-250 did not have any way to turn off overdrive. All '05 F-205s had a TOW/HAUL button which would not turn off overdrive.

 

Thanks.. not surprised I don't remember,
thanks for the correction.

 

So trying to clarify for my situation:

I DO NOT want to tow my trailer up the hill with trans gear selector in 2 or 1? This would be bad? Maybe 2nd would be bad (too high a gear for this situation and would cause extra heat), but 1st might be okay (somebody on my last trip told me to drop it into 1st low gear and start climbing)?

I'd be better off leaving the truck in Drive, and putting it into 4x4 Low mode (and likely do the Sous mod) to keep the front wheels from locking if not needed? Is this correct?

 

Yes, for a 10MPH climb, put it in 4LO on the transfer case and D on the column, and let the transmission decide from there. But if the tranny is "hunting" for gears, press OD off (or press tow/haul if that is the label on your shifter).

As to the mod to make it 2LO, really does not matter on a dirt/gravel road but can be worth the mod on hard pavement.

 

Putting it in 2 wont let the transmission shift into 3rd or 4th (OD)

Putting it in 1 wont let the transmission shift into 2nd, 3rd or 4th

Put it in 4 wheel low and go!

 

Yes, leave it in drive with the OD engaged in 4x4low range. Now this is on the dirt road. I also believe 220 although high will not hurt your trans for the time you will be towing. You shouldn't be seeing that high of temp in low range. And it should pull really well. Just remember to take it out when done. Needs to be in neutral with foot on the brake. If it don't come out, back up a little, then forward and try again. That does happen some times.

 

I do this in Mexico on the dirt roads but I find letting the hubs engage really reduces my turning radius while trying to turn around and launch a boat. The turning radius on the crew cabs already sucks on these trucks. I've been unplugging the PVH solenoid to remedy this but once I do the "Sous" mod I won't have to pull over and do that anymore.

 

I won't be able to put mine next to the 4WD switch because I have Park Aid there but I am hoping to put it next to the power point.

 

Thanks for the feedback everyone. I will give it a go in 4Low on the next trip. I changed the fluid in the transfer case yesterday in preparation for giving it a workout coming up.

 

It would be helpful to others if you report back on your findings, good luck with the test.

 

Correct.

Or to 1. When in 2 the transmission starts in 2 and stays in 2.

You can run up to 220F all day long with no problems. You can go as high as 250F for up to a half hour at a time.