View Full Version : Has anyone here "Defeated the ADD System" on a Toyota?

10-26-2011, 05:02 AM
I just picked up a new to me 96 t-100 4x4. (3.4l & auto trans)

The truck has a few problems, one being it will not engage into 4x4.

After a lot of research, it seems most likely to be the actuator, ADD relay or ADD switch.
I really do not like the ideal of ADD (Automatic Differential Disconnect). It works on vacuum lines and electronics. I would much rather have manual hubs.

After even more research I came across this article to completely bypass the ADD (Automatic Differential Disconnect) system.


It seems just a little too good to be true.

Has anyone here actually done this? Anyone have an opinion?

I guess my main questions are:

1. does it work as it should?
2. Do the dash lights still show "4x4 on"?
3. Any real downside?

Thanks in advance,

10-26-2011, 06:53 AM
I didn't read the whole link you listed. But I do know parts are interchangable between ADD and non-ADD. Find non-ADD parts and swap em out.

10-26-2011, 11:30 PM
I actually just pulled my front diff out and removed the actuator to prep it for shipping this morning. And yes, it looks that easy. Actuator is on the passenger side, 4 bolts and its out, you can engage 4wd by sliding the collar over. As the collar moves over it presses an indicator switch which turns your 4wd light on. I nearly did this mod when my actuator would not operate in cold weather.

And as Aikane said, if you get an electric actuator out of a newer tacoma/4runner it will bolt right in. Wiring it on the other hand will be another bag of fun.

10-27-2011, 09:26 AM
Yes it works, though later models use an electric motor instead of vacuum to move the shift fork.

11-03-2011, 11:39 PM
The 4X4Wire information is spot on! I just did the mod on my '90 4Runner (with changing out to manual hubs as well) and it works great. I was concerned that the 4x4 light would burn continuously, but it only comes on when the transfer case is shifted into 4x4.


11-04-2011, 12:02 AM
Yes, I defeated the ADD system by doing this...