Yukon 4wd question?

[Martinjmpr]

(Xposted from the Tahoe/Yukon forum, no replies on that one yet)
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OK so I'm still trolling Craigslist and other sites "window shopping" for trucks (I say window shopping because I can't really seriously shop until I sell my 4runner and that won't be until next year.)
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But I came across an ad for what purports to be a 2004 Yukon XL 1500 SLT. It had some interior pictures and I saw this:
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Up until now I had assumed that the 4wd Yukons came in two varieties: The Denali had a 6.0 V8 and AWD with no low range and the non-Denali models had the same 5.3 as the Suburban/Tahoe and the same 2 speed T-case with pushbutton controls next to the steering wheel. That would mean that the 4wd controls on a Yukon XL would either be identical to the ones on a Suburban (if the XL had the 5.3 engine) with the stacked 2hi/4hi/4lo buttons and the round "Auto 4wd" button, or if the XL had the 6.0 it would be AWD all the time and there would be no control at all, just a blank panel here.
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Is that not correct? What seems odd to me about this one is that there is no "Auto 4wd" button and that the top button (which would be the 2wd button if it was a Suburban or Tahoe) has the 'slippery road' thing which leads me to believe it may be the auto 4wd? So does that mean the 5.3 Yukon is always in "auto 4wd" mode with no straight "2wd" option?
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Dumb question, maybe, but was there ever an AWD GMC truck like this with a low range T-case?
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Thanks in advance. I'm learning!

 

[dar395]

My Yukon with the 5.3 (Which is an Option) comes with the three bottom stack the top one being 2wd, than Hi 4wd and Low 4wd. As far as I know the Yukon as well as the Tahoe standard engine is the smaller 4.6, the AWD system is also an option on the base package (Non-Denali) I've seen the Auto system on some trucks, I take it as an option as well. I like my simple, just the three bottons.

 

[Martinjmpr]

Never mind, got my answer. The control above is for the full-time 4wd transfer case and StabiliTrak system which was an option on some GM SUVs. It is a full time system with (AFAIK) no provision to lock the center diff. Reading through some of the forums it has a reputation of being rather problematic as well as returning worse MPG so I'm going to remember that when I start shopping.
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Dar it sounds like your Yukon has the standard system called AutoTrac that has 4 buttons, 2hi, 4hi, 4lo and a round button for "auto 4wd." The Auto 4wd apparently engages the front axle but leaves the T-case not engaged in 4wd until it detects slippage and then it engages the front axle.

 

[1stDeuce]

Actually, I believe all the low range equipped t-cases can lock the center diff. That would be the normal 4wd symbol. The squiggly symbol is for the unlocked 4wd position, which also keeps stabilitrac active. I think... It's been a while since I messed with one...

 

[Storz]

So the AWD Denali does in fact have Low Range?

 

[Martinjmpr]

So the AWD Denali does in fact have Low Range?

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No, the Denali does NOT have low range. For a few years towards the end of the GMT-800 series (2000 - 2006) GM offered "Stabilitrak" which was a full time 4wd system that incorporated a locking center differential and low range. This was a little bit different from the standard transfer case which had an "automatic 4wd" setting.
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As I understand it (I'm not an engineer so this may be a little bit off) the "automatic 4wd" system is not a true differential, instead it uses the ABS sensors to determine when the rear wheels are slipping and then through a series of clutches (I believe) it will activate the front driveshaft, putting the vehicle into 4wd. Once the slipping stops, the vehicle goes back to RWD.
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The Stabilitrak system, by contrast, was a true full time 4wd system with a center differential and was in 4wd all the time. The buttons on the dash let you lock the center differential or put it in low range. Stabilitrak was not very popular and it's not that easy to find. I don't think I've ever seen one in person.
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Stabilitrak equipped Tahoes/Yukonw and Suburbans/Yukon XLs (I don't know if it was ever offered on the Silverado/Sierra pickups) all had the standard 5.3l V8.
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This is different from the Denali package, which had the same drivetrain as the Cadillac Escalade with the 6.0 V8 and AWD (I would call it full time 4wd but GM usually refers to it as AWD) transfer case. The AWD transfer case has no controls and is non-lockable. There is no low range. You can identify this by noting that the area to the left of the steering wheel (where the 4wd controls on GMT-800 trucks usually sit) is a blank panel or a pocket - no buttons (obvlously this is the same on the 2wd GMT-800 trucks as well.)
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Hope that helps!

 

[Storz]

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No, the Denali does NOT have low range. For a few years towards the end of the GMT-800 series (2000 - 2006) GM offered "Stabilitrak" which was a full time 4wd system that incorporated a locking center differential and low range. This was a little bit different from the standard transfer case which had an "automatic 4wd" setting.
.
As I understand it (I'm not an engineer so this may be a little bit off) the "automatic 4wd" system is not a true differential, instead it uses the ABS sensors to determine when the rear wheels are slipping and then through a series of clutches (I believe) it will activate the front driveshaft, putting the vehicle into 4wd. Once the slipping stops, the vehicle goes back to RWD.
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The Stabilitrak system, by contrast, was a true full time 4wd system with a center differential and was in 4wd all the time. The buttons on the dash let you lock the center differential or put it in low range. Stabilitrak was not very popular and it's not that easy to find. I don't think I've ever seen one in person.
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Stabilitrak equipped Tahoes/Yukonw and Suburbans/Yukon XLs (I don't know if it was ever offered on the Silverado/Sierra pickups) all had the standard 5.3l V8.
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This is different from the Denali package, which had the same drivetrain as the Cadillac Escalade with the 6.0 V8 and AWD (I would call it full time 4wd but GM usually refers to it as AWD) transfer case. The AWD transfer case has no controls and is non-lockable. There is no low range. You can identify this by noting that the area to the left of the steering wheel (where the 4wd controls on GMT-800 trucks usually sit) is a blank panel or a pocket - no buttons (obvlously this is the same on the 2wd GMT-800 trucks as well.)
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Hope that helps!

Thanks

 

[tennesseewj]

Interesting...I've never stumbled across a Stabilitrak equipped rig that I recall. Sounds like it shares the same level of success as Quadra-steer, haha

 

[tennesseewj]

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No, the Denali does NOT have low range. For a few years towards the end of the GMT-800 series (2000 - 2006) GM offered "Stabilitrak" which was a full time 4wd system that incorporated a locking center differential and low range. This was a little bit different from the standard transfer case which had an "automatic 4wd" setting.
.
As I understand it (I'm not an engineer so this may be a little bit off) the "automatic 4wd" system is not a true differential, instead it uses the ABS sensors to determine when the rear wheels are slipping and then through a series of clutches (I believe) it will activate the front driveshaft, putting the vehicle into 4wd. Once the slipping stops, the vehicle goes back to RWD.
.
The Stabilitrak system, by contrast, was a true full time 4wd system with a center differential and was in 4wd all the time. The buttons on the dash let you lock the center differential or put it in low range. Stabilitrak was not very popular and it's not that easy to find. I don't think I've ever seen one in person.
.
Stabilitrak equipped Tahoes/Yukonw and Suburbans/Yukon XLs (I don't know if it was ever offered on the Silverado/Sierra pickups) all had the standard 5.3l V8.
.
This is different from the Denali package, which had the same drivetrain as the Cadillac Escalade with the 6.0 V8 and AWD (I would call it full time 4wd but GM usually refers to it as AWD) transfer case. The AWD transfer case has no controls and is non-lockable. There is no low range. You can identify this by noting that the area to the left of the steering wheel (where the 4wd controls on GMT-800 trucks usually sit) is a blank panel or a pocket - no buttons (obvlously this is the same on the 2wd GMT-800 trucks as well.)
.
Hope that helps!

I didn't catch this the first time I read through, but StabiliTrak on the GMT900 platform is the traction & stability control aid. It is totally separate from the 4x4 system and simply activates braking to limit wheel spin. It is very common on LT/LTZ trim Silverado/Sierras. Interesting that GM kept the Stabilitrak name for a seemingly different system.

The StabiliTrak button now serves to disable the system when allowing wheel slip may be desirable (such as off-road).