1991 Toyota surf wont shift into 4x4 properly

[91surf]

hi i just bought a 1991 toyota surf LN130, l2te auto, when i got it it had a pretty bad shudder and flat spot in the acceleration so i restarted the ecm and put a auto transmission treatment and it has improved alot, but i cant seem to engage the 4x4 via the 4 hi leaver, the leaver shifts fine and the 4x4 light goes on, but when i try to drive it feels very sluggish like half the power of 2 wheel drive is available and when i try to turn the steering wheel it almost sounds like the CV joints were creaking and the left rear side droops down, i have tried to check the vacuum lines to the diff and they seem ok, when 4x4 is engaged i can rotate the transfer case shaft half a rotation then in locks up.

is the 4x4 linked with the hard, soft setting automatically?

What other things can i check to find out if it is the transfer case or if it is the front diff?

Thanks

 

[fourwd1]

... the leaver shifts fine and the 4x4 light goes on, but when i try to drive it feels very sluggish like half the power of 2 wheel drive is available and when i try to turn the steering wheel it almost sounds like the CV joints were creaking and the left rear side droops down ...

That sounds like you in 4 Low instead of 4 Hi.

is the 4x4 linked with the hard, soft setting automatically?

hard soft setting ???

What other things can i check to find out if it is the transfer case or if it is the front diff?

Thanks

Remove the front drive shaft and see what happens

 

[91surf]

the hard/ soft setting for the rear shocks controlled via the button near the auto shifter and the rear electric window switch.

is 4L controlled via the gearbox ? or the transfer case?