Front differential non ingaging ?

I got a 1996 Tacoma 4x4 as you can see in my avatar.I recently had a motor swap done,now my front differential is not ingaging.I would notice before when I shifted the floor lever in 4wheel low,my green lite would come on dash.I checked my 4WD fuse,fine,looked under truck,noticed there are 2 plugs that is connected to the transfer case.Could this be a electrical issue?Fluid level works off transmission fluid correct? Everything worked fine before motor swap,,,HELP.

 

I'm guessing your truck has a J shift transfer case. If this is the case there are only sensors in it telling the ADD actuator to engage or disengage. I don't have any experience with the vacuum actuated ADD but that could be your issue.

 

I got my vacuum situation fixed,I am getting vacuum to the actuator. When I pull the shifter and move it over to the neutral position,my green 4whell light will flicker on dash and I can here a clicking noise like a relay?