front hub 4x4

Does anyone know if the front hubs on a 2005 tacoma is always engaged, just waiting to be put in 4wd, or does it engage as you put it into 4wd?

With my old 1990, I had to manualy engage the front hubs, so I actually knew when they were in.

 

'05 and up use an Automatic Differential Disconnect which disconnects one side of the axle

 

OK thanks..... but I was wondering with the ADD, is the front diff. or dirve axle always turning when in 2wd, after the transfer case has released from the front drive shaft??

 

from http://www.4x4wire.com/toyota/tech/add/ :



Toyota introduced the Automatic Differential Disconnect (ADD) 4-wheel drive system on its trucks in 1989, and on the 4Runner with the 1990 redesign. This system is composed of a vacuum-activated shift fork in the front differential driver's side axle tube: when the transfer case lever is moved to the 4Hi position, vacuum is applied to the fork which in turn moves a sleeve to lock the inner stub axle shaft from the carrier to another shaft in the tube. This axle assembly powers the driver's side wheel, while the passenger side is a single shaft from the carrier to the inner CV joint. While in 2WD, the driver's side axle is disconnected within the tube. The ADD trucks also have hub flanges at the wheels instead of conventional hubs; a series of vacuum switching valves (VSV's) in the engine bay to control the actuator; and a transfer case position indictor switch, which controls the dash light.

 

OK...thanks for everyone's help explaining this for me.