Forester

I have a 95 v6 automatic 4runner

My problem is it wont shift to 4L, only 4H. The light never comes on.
I read all other 4wd problem threads extensively and I cant seem to find this same problem.

What I do know:
vacuum is good, add works fine, only one solenoid works(the one that keeps the add engaged). From here i figured part of my problem was the add relay as it is not sending a signal to the other siloniod. I pulled the relay and it looks fine, although i don't know how i can tests if it works(any ideas?). Because the relay looks fine I believe the relay is not getting a signal from the t-case. What signals the relay? And how, or does, the signal to the relay relate with the t-case not engaging into 4L

At this point I believe my problem is the 4wd actuator on the drivers side of the t-case, but I am not sure how it works. Is the actuator completely mechanical, and if so what are the wires coming out of it for? Is there an electric motor in the actuator, or is this a sensor? Also, the lever for the actuator is smooth and if seems to fully "click" in all three positions(2h-4h-4l). How can I test whether the actuator works or not? And if this is not the culprit what is? Finally, where is the 4wd sensor on the t-case, and how can I tests if it works or not?

Summary:
How or can I test the add relay?
What signals the add relay?
How does the 4wd actuator work?
How do I test the 4wd actuator?
Where is the 4wd sensor, and how can I test it?

Sorry for so many questions, but any help would be much appreciated!
Joseph