Sequoia 4WD - how is it different from AWD?

mnwanders

New Member
Feb 9, 2017
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This feels like a bit of a dumb question but I realized today that I still really don't understand how the Sequoia 4WD works.

Background: I've been a 1st gen owner for 6 mos now, this isn't my first 4WD, I'm not mechanically illiterate, but I'm obviously not an expert, and I'm into this forum and others for the sole purpose of overlanding and exploring.

So I've read a bunch on the topic and I thought I understood the difference between AWD and 4WD until today. The crux of the issue is i don't understand how the basic unlocked differential 4WD configuration of the Sequoia is any different from AWD other than the vehicle now has the option to engage the front wheels (other than normal 2WD mode). To me, the only true 4WD must be when both front and rear differentials and the center differential are all locked. Am I wrong?

And for those Landcruiser types who love their full-time 4WD, if their diffs aren't locked, isn't that just the same as the Sequoia with the 4WD engaged?

Thanks ahead of time for the lesson.

Oh, and sorry if this the wrong area to post, it just didn't seem to fit in any of the other topics.


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Jim Smola

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Dec 28, 2016
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Inman SC
This feels like a bit of a dumb question but I realized today that I still really don't understand how the Sequoia 4WD works.

Background: I've been a 1st gen owner for 6 mos now, this isn't my first 4WD, I'm not mechanically illiterate, but I'm obviously not an expert, and I'm into this forum and others for the sole purpose of overlanding and exploring.

So I've read a bunch on the topic and I thought I understood the difference between AWD and 4WD until today. The crux of the issue is i don't understand how the basic unlocked differential 4WD configuration of the Sequoia is any different from AWD other than the vehicle now has the option to engage the front wheels (other than normal 2WD mode). To me, the only true 4WD must be when both front and rear differentials and the center differential are all locked. Am I wrong?

And for those Landcruiser types who love their full-time 4WD, if their diffs aren't locked, isn't that just the same as the Sequoia with the 4WD engaged?

Thanks ahead of time for the lesson.

Oh, and sorry if this the wrong area to post, it just didn't seem to fit in any of the other topics.


Sent from my iPhone using Tapatalk
Your correct that our 4wd is just as good and your correct that our 4wd is only all wheel drive. the center diff lock distributes 50/50. Our front and back differentials are open and to be 4 wheel drive we need lockers.
 
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Jim Smola

Moderator
Staff member
Dec 28, 2016
424
157
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Inman SC
This feels like a bit of a dumb question but I realized today that I still really don't understand how the Sequoia 4WD works.

Background: I've been a 1st gen owner for 6 mos now, this isn't my first 4WD, I'm not mechanically illiterate, but I'm obviously not an expert, and I'm into this forum and others for the sole purpose of overlanding and exploring.

So I've read a bunch on the topic and I thought I understood the difference between AWD and 4WD until today. The crux of the issue is i don't understand how the basic unlocked differential 4WD configuration of the Sequoia is any different from AWD other than the vehicle now has the option to engage the front wheels (other than normal 2WD mode). To me, the only true 4WD must be when both front and rear differentials and the center differential are all locked. Am I wrong?

And for those Landcruiser types who love their full-time 4WD, if their diffs aren't locked, isn't that just the same as the Sequoia with the 4WD engaged?

Thanks ahead of time for the lesson.

Oh, and sorry if this the wrong area to post, it just didn't seem to fit in any of the other topics.


Sent from my iPhone using Tapatalk
Also once the diff lock is engaged, all of the atrac is disabled.
 
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XPLORx4

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Jan 10, 2017
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Also once the diff lock is engaged, all of the vtrac is disabled.
I don't think that's the case in my '05. When the tcase is locked, the VSC system is disabled, but the TRAC system still applies braking to spinning wheels, functions as a sort of limited-slip diff, and allows some power to be transmitted to the wheels with more traction. I confirmed this by attempting the same obstacle with the brake fluid sensor disconnected (to disable VSC/TRAC) and with it connected (so that the TRAC system works), and I got a lot more wheelspin with TRAC disabled.
 

XPLORx4

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Jan 10, 2017
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To add to previous comments, the key difference between AWD and 4WD-capable vehicles is this:
1) AWD only: 3 differentials. Front, center, rear. Center diff cannot be locked. Also lacks 4WD low range gears. No option to use 2WD only. Center diff can dynamically transfer torque between front and rear axles as needed. The torque split depends on the specific design of the center diff.

2) part-time 4WD: 2 differentials. Front, rear. Center transfer case mechanically locks the front and rear driveshafts for 50:50 torque split. Typically also has 4WD low-range gears. Driver can shift between 2WD, 4WD-hi, 4WD-low. Most part-time 4WD systems have a console-mounted transfer case shifter.

3) AWD with locking center diff: 3 differentials. Front, center, rear. Center diff may be mechanically locked. Typically also has 4WD low-range gears. Driver can shift between 2WD, AWD, 4WD-hi (center diff locked), 4WD-low (center diff locked).

The Sequoia uses implementation #3.
 

mnwanders

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Feb 9, 2017
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Thanks for the help guys. That is definitely more clear.


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Scott Jackson

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Jan 10, 2017
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To add to this:

01-02 Sequoia DO not have ability to Lock the center Diff manually. It ONLY Locks in 4lo 1st gear.. so Reverse, 2nd and Drive, it unlocks and goes back to AWD. ( this can be VERY bad in off-road situation, like Snow Bank Busting) I have NO idea why Toyota did this.. Makes no sense. VSC is disabled by VSV OFF switch, and Low Range shift, . Trac always on... unfortunately. (Need to make a switch for that, so I can use it if I want, only when I want)

There is a wiring MOD to add your own Center Diff Lock switch. I think ALL 01-02 owners should do this if they plan on going off road.

03-05 Toyota added the Center diff lock button. (not sure if VSC, and trac are disabled, perhaps just 4 low??)

06-07 - Toyota to moved to 5 speed full electronic with a 60-40 ish torque split. It can be locked for 50/50 split as well.


Tip -

If you break a shaft, or Diff while in AWD, ALL the power will be pushed to the broken shaft, meaning... NO GO! This is why it's bad to use AWD while off-roading (dirt roads ok), if you lift a tire attempting to climb an obstacle, your entire rig will just stop moving, and could roll back.
I have personal experience with this, and it cost me dearly, as it broke a shaft when the wheel came back down, then I could not get the T-case to shift back into 2wd, just got the flashy lights. I had to get pulled to about 10 mph for it to sync up, then if finally when to 2wd after some horrifying noises you NEVER want to hear.
 

Jim Smola

Moderator
Staff member
Dec 28, 2016
424
157
43
Inman SC
To add to this:

01-02 Sequoia DO not have ability to Lock the center Diff manually. It ONLY Locks in 4lo 1st gear.. so Reverse, 2nd and Drive, it unlocks and goes back to AWD. ( this can be VERY bad in off-road situation, like Snow Bank Busting) I have NO idea why Toyota did this.. Makes no sense. VSC is disabled by VSV OFF switch, and Low Range shift, . Trac always on... unfortunately. (Need to make a switch for that, so I can use it if I want, only when I want)

There is a wiring MOD to add your own Center Diff Lock switch. I think ALL 01-02 owners should do this if they plan on going off road.

03-05 Toyota added the Center diff lock button. (not sure if VSC, and trac are disabled, perhaps just 4 low??)

06-07 - Toyota to moved to 5 speed full electronic with a 60-40 ish torque split. It can be locked for 50/50 split as well.


Tip -

If you break a shaft, or Diff while in AWD, ALL the power will be pushed to the broken shaft, meaning... NO GO! This is why it's bad to use AWD while off-roading (dirt roads ok), if you lift a tire attempting to climb an obstacle, your entire rig will just stop moving, and could roll back.
I have personal experience with this, and it cost me dearly, as it broke a shaft when the wheel came back down, then I could not get the T-case to shift back into 2wd, just got the flashy lights. I had to get pulled to about 10 mph for it to sync up, then if finally when to 2wd after some horrifying noises you NEVER want to hear.
Excellent!!
 

Westley Blevins

New Member
Jul 13, 2018
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North Texas
This one was very helpful to in understanding the way the AWD/4WD system works on my 2002. I have only used 4WD in a 2011 ram 1500 (you just turn a dial for 4hi, 4low, 4auto, 2wd) I'm glad I found this.
 

Atrac mobile

New Member
Sep 16, 2017
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To add to this:

01-02 Sequoia DO not have ability to Lock the center Diff manually. It ONLY Locks in 4lo 1st gear.. so Reverse, 2nd and Drive, it unlocks and goes back to AWD. ( this can be VERY bad in off-road situation, like Snow Bank Busting) I have NO idea why Toyota did this.. Makes no sense. VSC is disabled by VSV OFF switch, and Low Range shift, . Trac always on... unfortunately. (Need to make a switch for that, so I can use it if I want, only when I want)

There is a wiring MOD to add your own Center Diff Lock switch. I think ALL 01-02 owners should do this if they plan on going off road.

03-05 Toyota added the Center diff lock button. (not sure if VSC, and trac are disabled, perhaps just 4 low??)

06-07 - Toyota to moved to 5 speed full electronic with a 60-40 ish torque split. It can be locked for 50/50 split as well.


Tip -

If you break a shaft, or Diff while in AWD, ALL the power will be pushed to the broken shaft, meaning... NO GO! This is why it's bad to use AWD while off-roading (dirt roads ok), if you lift a tire attempting to climb an obstacle, your entire rig will just stop moving, and could roll back.
I have personal experience with this, and it cost me dearly, as it broke a shaft when the wheel came back down, then I could not get the T-case to shift back into 2wd, just got the flashy lights. I had to get pulled to about 10 mph for it to sync up, then if finally when to 2wd after some horrifying noises you NEVER want to hear.
I believe in 05 to 07, Toyota moved to a 5 speed.
Thanks.