92 4runner wont lock into 4wd

I have a 92 4runner with v6 5speed maneul tranny it has the A.D.D hubs ,when I put it in 4wd its not going into 4wd the 4wd indecator in dash is not coming on ,that could be a bad bulb cause it doesn't come on when you turn key on.The transfer case is working all right .Its something in the front end thats not engageing .I noticed on the front diff. there is some kind of solenoid there with vacuum hoses and a electrical connection .Does this have anything to do with it not locking into 4wd?

There are several switches, relays, and vacuum solenoids in the ADD system.
Lock and Unlock vac solenoids failures are common.

Check your actuator, not sure of the spelling, I had the same problem and replacing that fixed it.