Toyota Repair: 93 4runner 4wd light, vacuum ports, vacuum lines

Question
We have a 93 3.0L Automatic. After a light front impact our 4wd is not
engaging...no 4wd light...nothing. The impact was nowhere near the front diff so
I am lost as to how it happened. The truck still drives fine but it's just begun
snowing and we need our 4wd. I would like to fix it myself. Thank you so much
for your input.

Answer
It uses the ADD type of 4x4 engagement in which the front differential is engaged by a vacuum operated actuator, the switch to indicate that it is in 4x4 is also in the front differential so I suspect this is where the problem is, make sure the vacuum lines are connected to the actuator and the switching solenoid located on the left inner fender under the hood, if they are connected the actuator vacuum ports may be clogged, removing the actuator and cleaning the ports and then testing it on the bench to check for proper operation should take care of the problem.