Hey I'm new here and i just bought a 1990 Toyota pickup 4x4 5spd 22re
i tried the 4x4 and thought it worked because when i shift from 2h to 4h i can hear a click in the dash but the 4x4 light does not come on, so i tried 4l and it felt like it was working because the gear ratio was so low so i figure the transfer case is ok. so i tried using 4h to get out of a little jam and the front wheels were not spinning.
what are the things i should check first
please help

 

Connectors on transmisson. Any hanging off or not in the right place? Wheel hubs locked?

 

Well I looked underneath and didn't see anything hanging or anything and if I'm not mistaken the front hubs are always engaged I think the diff has something engage the axles

 

Do you manual lockers or auto? if namual you have to get out and turn them.... if auto then no.... you could jack the rear off the ground and put it in 4wd and see if it pulls the truck off the jack lol. Or jack it all up on stands and see..... if the front wheels are not turning and the light is off.... then something is disconnected.... look hard... i hard the same issue after i did a clutch in a buddys truck i forgot to reconnect one lil connector and it kept the 4wd from working......

 

vacuum lines, or electrical connectors to the front diff.

 

If it's got ADD read this.
http://www.off-road.com/trucks4x4/ar....jsp?id=399612

 

I had exactly the same problem. It was a vacuum line the got connected incorrectly the last time it was in the shop. Follow the vacuum line up from the ADD up to the passenger side of the engine bay. It goes into a small black box and comes out the other end. With the engine running, pull the line and see if there is any vacuum there.

 

The click in the dash means the switch at the t-case works, but the light not coming on means the actuator is not moving over to engage the diff w/ the axle. So, somehow you are not getting vacuum or the actuator itself is not working right.

Look at the front diff for the two vacuum lines going to the actuator to right (as your facing it) of the diff. If they aren't disconnected there and/or have no holes in them, trace them back all the way to the two vacuum switches they go to. Not sure where they are on your truck. They're under the hood on top of the pass. side wheelwell in a 2nd gen 4rnr. Anyway, make sure they are connected there and that the switches function = creating vacuum. If all appears well, the hoses may just be switched around.

 

thanks for all the help guys. It seems the steel connector for the vacuum line rotted away so now i just have to figure out if i can fix it or if i have to replace the add

 

How badly? Can you get a pic?

 

not really sure exactly how add works but would just switching to manual hubs fix this and negate the need for the vacuum lines? probably a noob question but im just trying to learn!

 

no... with the add flanges, your hubs are always locked... the problem u are having is that your front diff is not engaging. Gotta fix thos vacuum lines, or manually lock the diff. then add the manual hubs.

 

i managed to drill out the broken connector and pressed in a piece of 3/16 brake line as a new connector and reconnected the vacuum line now the 4x4 works great. thanks for all the replies and suggestions i really appreciate it

 

This same dang thing happened to me after my buddy rebuilt my transmission!! Thanks to this thread I can show him where he f-ed up or just do it myself. Since I paid to have the thing fixed to begin with, and I got stuck once, I might as well have him do it.

 

I was going to suggest something like that. S'why I asked how bad it was broken. Congrats to a DIY'r...

 

hey guys im having a similar problem with my front diff not engaging im getting the light on the dash coming on so im assuming that the actuator is engaging the switch and i have check and do get vacume from the right hoses at the add what else could be wrong if the actuator is engaging the light transfer case is good front drive shaft engages when in 4wd
does there need to be a certian amount of vacume to engage the diff over and less vacume to engage the switch?
help would be nice

cheers
frank