4x4 Speed Sensitive Gear Buzz, Not Engaging

[MotoCARR]

Probably not the best timing on my part to see if my new to me 95 Tahoe's 4x4 works but here's where I am at. Over the weekend dropped trans pan and replaced fluid/filter and shift solenoids and at the same time checked fluid levels in the center transfercase and front "diff"/gearbox.
•Center transfercase was full, slowly backed the drain plug out and the fluid that seeped out was nice and clean.
•Pulled fill plug from the top of the front diff/gearbox, stuck my finger in there and could not feel any fluid at all. 1.5QT of 80W90 later, it starts to seep out the hole and I can feel the fluid level with my finger. I'm not sure how long it has been like this, I have driven the truck about 5-600 miles and have never activated the 4x4.

Here is how I went to engage 4x4:
•Slow to 1-2mph
•Shift truck to neutral (N)
•Pull 4x4 lever down to 4H
•Shift truck to drive (D)

The video below is the gear whurrr/buzz I hear after going through the steps above.
•Drive the truck and there is a speed sensitive buzz/whurr while driving.
•ABS kicking in as I come to a stop 0:14 sec mark
•Once I start going again, buzz/whurrr is gone

At no point is the 4x4 engaged, verified this by turning my wheel and looking out the window while sitting on 1-2" of packed snow/ice.



Thoughts!?

https://www.youtube.com/watch?v=Ve3KPEnYg7o&feature=player_embedded

 

[badazzbulldog]

you dont need to go into neutral to put the truck in 4 hi,i think the noise your getting is the front diff not fully locked in when you stop and start again is when it kicks in

 

[MotoCARR]

you dont need to go into neutral to put the truck in 4 hi,i think the noise your getting is the front diff not fully locked in when you stop and start again is when it kicks in

Thanks for the info, maybe I was reading how to engage 4L then? So i can be driving and just pull the lever back to 4H to engage 4x4?

 

[98_k1500]

As long as you are not spinning. Just coasting at low speed. Its not good on the shift forks to put it in at like 70.

 

[95Suburban]

Yep, any legal speed.

Sent from my 831C using Tapatalk

 

[MotoCARR]

As long as you are not spinning. Just coasting at low speed. Its not good on the shift forks to put it in at like 70.

So driving at 10-20mph, let off the gas, pull the lever, back on the gas. Ok to do this while still in drive at that speed?

 

[98_k1500]

So driving at 10-20mph, let off the gas, pull the lever, back on the gas. Ok to do this while still in drive at that speed?

Yup. Thats it. Shifting like that should be pretty much instantaneous with no strange noises.

 

[MotoCARR]

Yup. Thats it. Shifting like that should be pretty much instantaneous with no strange noises.

Awesome thanks for the info everyone, I'll give it a go tonight in the 3-5 inches we are supposed to get tonight