KZJ78 stuck in 4wd (1 Viewer)

[yotaland]

Hi all,

I recently bought a KZJ78 that appears to be stuck in 4WD with the hubs unlocked. The front prop shaft spins when the car drives (and can't spin by hand), but both front wheels turn freely when jacked up.

Neither the hub lock nor the 4WD buttons work or light up when pushed. I have seen that I can manually disengage 4WD by switching the vacuum lines?

Has anyone had this before, and does anyone know where I should start looking?

Thanks!

 

[Tanner H]

Check out this older thread. Seems like a similar problem.

2

Thread 'LJ78 JDM 4WD Problem'

Jun 1, 2008

I have a 1990 LJ78 Prado SX5, when I first start it in the morning I can push the hub button and the indicator light will come on, I then push the 4WD button and the indicator light comes on. I then switch the 4WD drive and hub button off and both indicator lights go out. So the vehicle is cold and everything works 100% of the time. I then drive the vehicle until it is up to temperature and do the same test. The hub light comes on 100% of the time but the 4WD light will not come on. This is not intermitten it is repeatable each time the vehicle is warmed up. I am pretty confident...

• 2001Slayer
• Replies: 18
• Forum: 70-Series Tech

Losing vacuum when the truck warms up for some reason maybe??? Drive until the 4WD does not engage, then pop the hood and check for incoming and outgoing vacuum at the VSV valves per the pic. The hoses marked with red arrows are incoming. Check incoming vacuum by pulling both hoses, cap one with your finger, check for vacuum at the other. Check outgoing vacuum by pulling one hose at a time and checking for vacuum at the plastic nipple (blue arrows). If hub lock and 4WD are switched off at the dash, vacuum should be present coming out of the top VSV. If hub lock and 4WD are switched on at the dash, vacuum should be present coming out of the bottom VSV. If vaccum coming out of the VSV is not as it should be, could be indicative of a valve problem or electrical problem. If you reinstall the outgoing hoses backward, the 4WD dash switch will work backward. Shot in the dark...HTH.
View attachment 235303

 

[Rigster]

Check the "4WD" switch in the dash. Verify the plug is still soundly connected/seated properly to the switch. If this plug is disconnected, it will remain in 4WD

 

[Tanner H]

@Rigster I was thinking that too..but i would assume the dash light and hub lock light would blink? Maybe not.

Also thought maybe the 4wd system was not working for the previous owner and maybe they simply pulled the bulbs out of the cluster before selling.