4wd issue.

I was in a slight accident, where driver side front wheel was broke off. Had to replace rack and pinion cause it's stripped out the area where the rod screws in, both control arms and cv joint. Sat for 2 years while I traveled for work. I ran it everyweekend I made it home, never saw any 4wd lights.
I got the truck fixed at a local reputable autoshop. Know that truck is fixed, the 4 lo light is flashing, with no beeping, and won't go into 4wd. It is deffinitly in 2wd cause when driving the rpms where normal. Any ideas as to what it may be. The mechanic said the switch is prob bad, bit didn't seem sure of himself.
The truck drives good and had computer scanned for any codes none found? Pls help me out if possible. Thank you all!

 

With it sitting for that long my guess would be the 4wd actuator. But that’s just a guess. Plus it was in an accident so there could be something damaged.

In 4 high the rpms will not change.

 

I climbed under the truck and found a rectangular plug with 5 or 6 spaces in it hanging, is this for the 4wd? It is in middle of truck between rack and pinion and the axel

 

Yep, plug that in and your 4wd should work

It goes on top of that black box. that's your 4wd actuator in the pic