i have a 1990 v6 extended cab pickup that is an automatic and i just got a new motor installed and i tried the other day to engage it into 4 wheel drive and the light doesnt come on and the front wheels dont engage. i was told it most likely was a vacuum problem so i checked the two vacuum lines comming off the transfer case for leaks and i didnt seem to find any does anyone have an idea of how to fix this and what to test. maybe a vacuum line diagram. anything will be apreciated

 

Welcome to YotaTech .... is it possible you got the vacuum lines reversed ?

 

try reving the motor for a few seconds and see if it engages, if it does then its def. a vacuum leak

 

If you have ADD, the vacuum lines will go from the front differential to two valve switches located on I believe the passenger side fender just to the left of the p/s pump.

 

Also check the electrical wire that connect to the front of the front differential, the wire goes through your alternator to the wire harness so check that if it is connected, it might of be disconnected, mine has that problem and it was the wire has disconnected like someone did it on purpose.

 

i have checked the vacuum lines and i have switched them and thats not the problem and it seems like the electrical is connected well i beleive i need to check to see if i get power and if i get vacuum. the two vacuum lines come off the transfer case and go to the blue and red things that are on the passenger side of the truck and i have checked those and they seem like there in the right place but it still doesnt work and i have tried to switch those. if i was to check the vacuum and the electrical what should they read

 

ditto everything said.

 

Not to doubt you, but are you sure it isn't engaging? It could just be your 4WD sensor is bad so the little light doesn't come on.

 

i have checked to make sure it that it didnt work i would go in gravel and have someone watch while i punched it and only the back tires would spin

 

my 4runner crabs really bad on pavement, almost more so than my pickup. thats how i know its working

 

does it have auto hubs or manual.....because i have herd stories of the auto hubs going bad. my cousin is having the same problem and i think the hubs are bad.

 

auto hubs suck