Okay, I have a '94 4runner, auto, 4wd. The 4wd is not working. I did a manual hub swap recently, but I don't think the problem is in the hubs. With the front end jacked up off the ground, and the hubs locked, the cv axles turn but the front driveline does not and when I unlock the hubs the cv axles don't turn. When I put it in 4wd the light does not come on. I blew the engine this summer and put in a rebuilt one, so maybe something is disconnected from when I did the engine swap? I haven't really used the 4wd enough since them to know if it worked then. Could this be a vacuum problem? Can somebody help me out with the location and description of the vacuum lines I need to check? Help would be greatly appreciated. Thanks.

 

Sounds like the vaccuum disconnect on the axle isnt working properly.... check the vacuum lines is a good place to start.

There should be a little box on the axle that has a vacuum line, follow it, or see if its connected.

 

The little box on the drivers side of the differentail has two vacuum lines - one engages ADD and the other disengages the ADD.

There is a bank of solenoids on the Pass side fender (under the hood) that these two vac lines come from. THey are electric solenoids that switch the vacuum from one line to the other.

So, you could have a vac hose disconnected somewhere or you could have a wire disconnected somewhere.

Or you could also have a transfer case problem....

 

In the same sentence, you could mention the switch on the transfer case that activates the solenoid.

 

Okay, so far I have not seen any holes in the vacuum lines where they hook up to the little box or to the solenoids. When I have the hubs locked and shift into 4wd, I can here a click that sounds like a relay or something? Sounds like it could be coming from behind the gauge cluster maybe... Any suggestions on what to check next and how to check it? Thanks.