I have a 96 Explorer XLT V6. It has developed a problem with the 4WD. When I
put it into 4WD high the light comes on but does not engage the front
wheels. I can then put it in N and switch it to 4WD low and can hear the
actuator motor switch to Low 4WD, I also see the light on. Again the front
wheels do not engage. Have removed the actuator motor from the transfer case
to check and see if it works and it does. So I put the truck up on stands
and wanted to see if the front wheels turn and they did. So a friend and I
put pressure against the tires and were able to stop the tires. I am at a
lost what could be the problem, any suggestions?

 

Did the '96 Explorer use the vacuum disconnect on the front axle?

 

Yes, there is two vacuum lines attached to a round object that is connected to the front axle. I have check the vacuum on these lines and seems to have some vacuum there. I do not have a tester to see how much vacuum.

 

that would be the first thing to check but if it is 4x4 auto it will only engage when it needs to

when was the last time you changed the transfer case fluid

 

You should not be able to stop the tires. The vacuum shift motor on the front axle is driven open and driven closed. That means there will always be a vacuum on one of the lines going to the motor. I think that's where your problem is.
If you follow those lines back up to the Vacuum shift relay It might be bad. I think you can bypass it and send vacuum to each line directly and see if your front axle engages.