Bj 74 - 4wd system

[chui]

HI.
Have a BJ74 which is giving me a huge headache with the 4LOW system for 4w drive. Once engaged into 4 low (hubs locked etc) the front wheel dont move. Realized that the centre diff does not lock. I have no H4 Button. Have come to realize that the vacuum soleniod may have issues even though the vacuum still works. But sometimes it engages other times it fails.
Have now locked the centre diff manually. Front and rear diff working during normal driving. So I just need to lock the font hubs and I will be in H4.
Wanted to know:
1. Can I mess up my front diff by doing that (locking centre diff manually). I can always open it up and unlock it. The hubs however are not locked during normal driving.
2. Where can I get a vacuum solenoid and H4 Button / switch from. The button is 4 pin so I cant use any other kind of switch. Here no one has anything. Is there any alternative or will I have to import it? Can I use parts from the 75, 78, 79 or 80 series. The 79 series is the local toyota dealers sole car they sell so they will be stocked. Is the vacuum solenoid the same as the BJ74?
3. The 4wd (4low) does not enage . Changed the vacuum switches, bearings, checked cv jints, front axle, diff, but nothing. The light on the dash board showing the 4wd, sometimes the rear diff light, switches on other times it doesnt work. Have no idea why? What could be the problem?

Thanks a lot. PS Im in Kenya - East Africa

 

[roscoFJ73]

You dont actually have a centre diff,its a part time transfer case.

In all honesty ,you would be better off converting it to a manual shift and scrapping the vacuum system altogether.
The vac system is normally quite reliable but East Africa is not going to be the easiest place to fix this
You would need the front plate from a manual t/case and the shift mechanism ,although others have converted the vac shift mechanism to a manual set up.
Maybe someone can chime in and give directions for this

I dont think you are harming the t case by driving with it in 4H with the hubs unlocked,at least if you keep the speed down.

You would have to see if the 79 series uses the same type of shift mechanism,all the australian 79 series are shifted manually

 

[chui]

hi.. thanks...
any further info on how to change to a manual system..