No 4wd

[WAZ]

I am new to the 4Runner and this is my first 4WD. So please excuse my lack of knowledge. When I shift my 1990 4Runner in Four-wheel the light does not come on in the dash instrument cluster and the front wheels don't get drive. Where is the first place to start looking.

I normally do my own work on my cars. I have have the 1990 Service Manual. So have some experience. Thanks for any help.
Waz

 

[TSP-MIKE]

I'm guessing you have ADD (Automatic Differential Disconnect). If so you will need to see if the solenoid on the front differential and see if it's connected and works. If everything looks visually fine then check the vacuum lines going to the solenoid, make sure there are no breaks in it. If all that is ok then check the vsv valve that those vacuum lines are connected to and test them.

The 4WD high is just a big circuit. When you put it in 4wd, it lets power goto the 4wd solenoid in the transfercase, then to the vsv valve that controls the ADD.

For the light circuit, when you put it in 4wd, there is a switch that goes from the transfer case to a switch in the ADD then to the 4WD light on the dash. There are 3 things to look for here, First is the fuse, Second check the switch on the the transfercase and see if it works, third check the switch on the ADD. If any one of those switched don't work then that is what causing the light not to work.

Hope this help

Mike