I have a '91 4Runner and the four wheel drive is not engaging in the front differential. It has auto locking hubs. When I engage the 4x4 the front drive shaft turns but it's just not locking in there in the front differential. Any ideas on what to check to git 'er workin' again? All help is much appreciated!

 

Isn't there suppose to be vacuum lines going to the diff? Check it. Hope you're testing this on dirt.

 

I'm kinda new to 4Runners but I believe the front axles are activated by air (engine vacuum). So you may wanna start looking under the truck and check for cracked/dis-connected/missing hoses.....

 

Thanks guys! I will check the vacuum hoses manana.

 

Don't know much about the auto differential disconnect(ADD), but it is operated by vacuum which engages a slide coupler in the driver side front axle shaft.

 

you might want to do a little searching... there are tons of threads on fixing the 4wd. now depending if u are auto or manual there are many diffrent switches and vacuum lines, so when u put it in 4wd do u hear a click from the behind the dash? also here is a link for a repair manual for the 4wd..

http://www.ncttora.com/fsm/1993/susp...26addcontr.pdf

 

my buddys runner did the same thing check/clean lines also check little vacuums in engine bay