oh boy... hold up here.. what the hey is engine braking?
Well I see 3 questions here;
1) so are you saying a 2018 Ram 1500's 4WD Lock is not true 4x4,
it depends on the trim level of your vehicle, the "upper" trim levels with a transfer case that has the auto 4wd mode,
correct it uses a single disk wet clutch with a cam assisted function to engage the front axle drive. The trucks computer controls the activation of that clutch, this clutch and it's activation is when the computer decides to in auto 4wd and hi "lock" 4wd that is why you can do figure 8's in a parking lot with almost no binding or wheel hop.
2) Would you ever use 4WD Lock while driving on a snowy, slippery highway? The take away here I'm seeing is just slow down haha
,
certainly can if it's snow covered or slick that's what it's for, slowing down is just a prudent thing to do.
3) oh boy... hold up here.. what the hey is engine braking?
Engine braking is what you feel slowing your truck down when you lift off the throttle or downshift the transmission to slow the truck. If you put your truck in 1st gear and head down hill with no throttle applied the truck is pushing and the engine is trying to slow the truck down, low range will do even more.
The problem with the transfer cases with auto 4wd is that in conditions of extremely low traction at the rear wheels, is that the cam that aids (actually does most) in clamping the transfer case clutch doesn't have any force to aid in engagement then the rear wheels can slip and not hold in the front axle and you lose engine braking in those conditions, yes you can try and use your brakes and have the abs kick in and allow you to have no control.
I like my truck in every way except the transfer case operation in extremely low traction conditions, this transfer case is nice under 90% of it's use for me, and I use it every day in my driveway.