Is that normal when I engage 4X4 that...
 

This is my first vehicle with 4X4 manual engagement. I only had automatic as request 4X4.

If I engage either 4X4 high or low and then turn my steering fully CW or CCW and then move forward or reverse, it look like the brake are partially engage. I feel I need to push more on the gas pedal to have the truck move, it move like if the differential is lock, and when I release the gas I feel the brake reapply, the truck stop within a feet or 2. If my steering is straight I don't feel that.

Yes, normal behavior for "true" 4x4. Reference your owners manual for a full explanation. Basically, you only want to use 4x4 on a loose/slippery surface where the front tires can easily scrub, especially when turning.

Normal Yes wise practice no unless you are on slippery surface.

You may want to read this before you use the 4x4 system on pavement:

http://www.4x4abc.com/4WD101/def_turnpart.html

Thanks...actually I did engage the 4x4 because it was raining like hell and had lots of water accumulation on the road. Is that ok to engage the 4X4 with weather like that?
And in winter when you have mix surface of asphalt and snow/ice, like on a road but is is not actually snowing but that you could suddenly have your wheels on slippery surface but not 100% of the time, can I engage it ?

Sorry if it’s in your signature (on mobile can’t see it), but what trim do you have?

In my experience, on mixed surfaces, I will engage 4 hi if I’m at a stop light or some other low speed or stopped point. Once I get going I will switch back to 2 hi. At traveling speed, 4x4 is not going to help you very much and I have found I’m better off driving for the conditions in 2 wheel drive than feeling or hearing the binding. It’s the getting up a hill or starting from a stop that are tricky, and that’s where I use 4x4. For XL/XLT trims it’s more work doing manually, but that’s the price we pay for not having 4A.

I’ll add, a true 4x4 (4H or 4L) don’t work well as insurance as AWD or 4A would, they are better at being used only when required.

F150 2017 / 5.0 6SP / XLT 300A / Lightning blue / 18" LT tires 4x4 SCREW 157" WB / Tow package, 3.73 HDPP, PAYLOAD 2473 lbs

Ok so in a snow storm is it ok the leave it 100% of the time?

Thanks, just wanted to confirm that you do not have the 4A mode. I would avoid using 4x4 in the rain, unless you are trying to launch from a stop in a straight line. At high torque it is slippery, but not slippery enough to release the binding that happens when you take a corner.

If there is a layer of snow on the ground, or I am on loose gravel, I do leave it in 4x4 100% unless I am making very sharp turns (parking lots or hairpin curves for example). Sometimes if I am on the highway, I will take it back to 2 hi if I’m just cruising and not experiencing any problems.