Automatic locking hubs??

Sorry if this has been asked/answered before. I tried search and couldn't find anything but I'm not even sure I know the right search terms so I'm coming the experts on TW!

Question is: does my 4x4 ('07 DC) have automatic locking hubs of some sort? I've started to wonder if, in 2wd of course, the front axle shafts turn driving the front differential? That would seem a real throw back as the mechanical drag is a totally unnecessary hit to MPG.

In short: I'm not really certain exactly how the electronic transfer case works. Again, if this has been answered or there's a FAQ that covers this somewhere just point me to it!

Thanks much...

 

i wish i knew also. the only thing i can think of is to have someone else drive your truck while you look underneath and see if the prop and axle shafts are turning. i wish they would go back to manual shifting t. cases and lock outs. that way there is no bones about it.

 

From what I was told by the dealer, they're always locked, the engage is a vac operated solenoid in the front end

 

Then I guess the only way to know for sure the diffy's 'in' it would be to lift the front end and (making sure it was in 2WD before lifting it) rotate one tire...if the other one rotates in opposite direction then it is!

I could kick myself now... I should have done this when they had it on lift getting new tires.

Anyone doing a brake job?

 

Hubs are always locked in. Disconnect is in the transfer case. Yes it a drag. Pun intended...

 

woo hoo! got this off of ToyotaNation...

"You can think of the hubs as "always locked." The axles always rotate with the tires.

The ADD system disconnects the axle shafts from the differential. It just has to do one side, the action of the differential lets the side gears freely spin if just one shaft is attached, so the carrier doesn't move.

Finally, the actuator motor on the front of the axle tube is a vacuum one, not electrical. It operates a fork that moves a splined sleeve that connects and disconnects the axle shafts. If you remove it you could probably move sleeve manually. But just disconnecting the vacuum line might do it too, at least in one direction. Depending on the problem."

So the axles spin, but the diffy is effectively taken out by the splined shaft. I hope the t-case is also taken out of the drive line so THAT drag is removed?

ADDED BY EDIT:
DUHH...of course the t-case is taken out: I could turn the front drive shaft by hand when I was lubing the u-joints.

 

Current Toyota's use a system called Automatic Differential Disconnect (ADD)

The first 4x4 vehicles used a live hub, it was always locked then Warn came along and made a locking hub which was actually an unlocking hub because it allowed you to unlock the hub and let it free wheel.
Then manufactures started using automatic locking hubs, the problem was you needed to stop and back up for it to engage.

With the ADD you still have a live hub (always locked, the front axles turn with the wheel) but it disconnects the differential.

 

Interesting, good info. I do not recall seeing any lines (electrical or vacuum) going into the front diff....

 

Thank you... I have been (incorrectly) saying it does have 'auto locking hubs', as I didn't know there was another method of disconnecting the front differential gears from running in 2WD... ADD, hmmm!

I guess ADD accomplishes the same thing as Auto Hubs, but better since you don't need to back up after going into 2WD!?