problem with ADD
 

I just bought a 1991 toyota because it has a 22 re and a five speed the down fall is the auto locking hubs are not locking in i suspect a bad switch the problem. but i don't know where the swich is located. is it on the t-case or on the shift lever?

any help is apreed :bang:

does it have auto lockign hubs or the ADD

Automatic differential disconnect...
Is there a bunch of vacuum lines on the front diff?

how can you tell the differance?

This will help you see what is going on, not necessarily your solution:
http://www.4x4wire.com/toyota/tech/add/

Auto hubs and ADD are NOT the same thing.

:guitar:

yes there are vacuum line on the front of the diff

EDIT" nvm

Thanks wabbit.


I had a problem with my ADD system, it was no longer getting vacuum to keep the shift fork locked, which wouldn't allow the front wheels to put the power to the ground.
I ended up bypassing the VSV's and ran a vacuum line directly from the ADD shift tube to the engine, this kept constant vacuum on my shift fork.
Before that i added manual locking hubs so i could unlock them and not have the cv's spin.

If you are going to do this you will need manual locking hubs.

Auto hubs were 84-89 only I believe, so he has ADD.

Some more info:
http://www.4x4wire.com/toyota/tech/autohub/

:guitar:

Werent auto locking hubs phased out/replaced by ADD in like '87..'88 or so?

so it has to be ADD :)

EDIT: Wabbit said it before i did :)

in my eyes the cure would come in the form of a solid axle swap. but untill then i want to see if i can make what i have work. also my 4 wheel drive light does not come on. any idea where the swich is ?

Well when you throw the TC in 4wd it sends a signal to the vsv to creat vacuum.

Your light will only come on if that shift fork is locked

is there a switch that is trigered when you put it in 4 ?

Yes:
- http://www.off-road.com/trucks4x4/ar....jsp?id=399612

thanks for the help. now i understand my truck better. and what i need to do next