4x4 wont engage sometimes.

All of this is from memory so don't fault me if I'm wrong. With the manual hubs unlocked both front wheels spin independently even with the transfer case engaged. The transfer case will engage when the 4x4 button is pushed and is under a certain speed, should be less than 15mph or so. Once in 4wd you can then lock in the hubs to fully realize 4wd function. The factory hubs were auto locking and prone to failure, warn was the preferred replacement for them. If the transfer case shift motor is faulty or did not fully shift into it's selected gear all of the clicking and clanking was heard at the transfer case but the lamp at the button would not stay on after the attempted shift. To shift into 4low required the vehicle to be in park or neutral and the foot brake applied, this is also required for shifting out of 4low. There is a relay that is controlled by the push button switch that provides power to the shift motor if it is bad then the truck would make no attempts at shifting at all, It sounds like the shift motor is probably weak and unable to move it's mechanism with any resistance present. The fact that it will shift into 4wh leads me to believe that if you unlock the front hubs put it into neutral and set the brake prior to shifting it may shift more reliably. once its in 4wh leave it there, you can unlock the front hubs whenever 4wd isn't needed. It may be a bit of a hassle but by judging by your previous post the snow is normal where you are. Ford has deleted all of the online info about your truck since they've deemed everything older as obsolete.

You are saying: Unlock the hubs, put it into neutral THEN put the E brake down( the part you step on with left foot) And then push the 4x4 button?

Yes but this order, unlock, ebarake, neutral, foot brake held when pressing selector button. if it shifts the transfer case and you don't think that it will do it again leave it in 4wh. Then you can lock and unlock the front hubs as you deem necessary. The only reason for the ebrake while in neutral is extra safety.

I tried that. Did not work. When I push it, it drains a lil power from car, and I see the voltage meter on dash move a little bit. Any idea? Thanks again guys!

Also, I dont know if this helps. But my heater sometimes doesn't tirn on. But if you hit a bump, or slam the door it goes on great n stays on. Also, when I go to start my car. It displays " rear anti lock" in the same are as 4x4 n low oil amber lights up. But it does not display the 4x4 when I start it up. But I do here it in the back trying to click etc.