2005 Denali XL AWD - How does AWD work?

[amallano]

So, the short story is I rammed a snow mound in reverse and proceeded to lift the rear end off the ground. I know, I know. The front tires were still on the ground on blacktop. However I was stuck. The rear wheels were spinning, and the front was just sitting there. I would have assumed that the fronts would have pulled me out. I even shut off Traction Control..no dice. Had the embarrassment of having an Explorer basically idle me out. Any ideas why the front didn't engage and pull me out? I hope this is just my inexperience on how this AWD works and is not indicative of a major issue. Thanks in advance...

 

[Yukon John]

With any 1 wheel off the ground AWD will not engage. The Transfer Case with all wheel drive has a clutch in it that allows differential between front and rear. To out smart the system you may have had success by setting the parking brake fooling the clutches in the transfer case into thinking the rear wheels were on the ground getting some traction.

Another trick that works sometimes is to apply the brakes and gas simultaneously with the traction control on...this starts a "stutter" of sorts with the ECM supplying power to alternate wheels.

I have actually done this on a 2005 Escalade AWD pulling a boat up a slippery ramp.

AWD systems cannot be "locked" as conventional 4 wheel drive can.

 

[Rocket Man]

Why do all 4 wheels turn when my Denali AWD is on a lift then? I was having a corvette servo installed and the tranny shop had mine on a lift and they started it and ran it up to about 40 mph and all 4 wheels were turning.

 

[Yukon John]

Why do all 4 wheels turn when my Denali AWD is on a lift then? I was having a corvette servo installed and the tranny shop had mine on a lift and they started it and ran it up to about 40 mph and all 4 wheels were turning.

The clutches in the transfer case are free wheeling. The same thing happens when you put a Non Posi single leg rear axle in the air...both rear wheels will spin. Often times you can hold the left rear, put the vehicle in gear and the right rear will spin....don't try it with Posi !!

 

[nharkey85]

With any 1 wheel off the ground AWD will not engage. The Transfer Case with all wheel drive has a clutch in it that allows differential between front and rear. To out smart the system you may have had success by setting the parking brake fooling the clutches in the transfer case into thinking the rear wheels were on the ground getting some traction.

Another trick that works sometimes is to apply the brakes and gas simultaneously with the traction control on...this starts a "stutter" of sorts with the ECM supplying power to alternate wheels.

I have actually done this on a 2005 Escalade AWD pulling a boat up a slippery ramp.

AWD systems cannot be "locked" as conventional 4 wheel drive can.

Second this. We used this concept on 4wheelers back in the day

 

[amallano]

With any 1 wheel off the ground AWD will not engage. The Transfer Case with all wheel drive has a clutch in it that allows differential between front and rear. To out smart the system you may have had success by setting the parking brake fooling the clutches in the transfer case into thinking the rear wheels were on the ground getting some traction.

Another trick that works sometimes is to apply the brakes and gas simultaneously with the traction control on...this starts a "stutter" of sorts with the ECM supplying power to alternate wheels.

I have actually done this on a 2005 Escalade AWD pulling a boat up a slippery ramp.

AWD systems cannot be "locked" as conventional 4 wheel drive can.

Thanks much for the reponse. I guess it makes sense but it is kinda sad. Of course I am the dope that put myself in that situation. Certainly, I know a locked differential 4x4 would have been different. Maybe a Yukon SLE in my future! Thanks again.

 

[afpj]

With any 1 wheel off the ground AWD will not engage.

Sorry, I'm not understanding this so appreciate some learning.. If one wheel is on ice, wouldn't it be like being off the ground? Shouldn't the other wheels take over?

 

[Rivieraracing]

With any 1 wheel off the ground AWD will not engage. The Transfer Case with all wheel drive has a clutch in it that allows differential between front and rear. To out smart the system you may have had success by setting the parking brake fooling the clutches in the transfer case into thinking the rear wheels were on the ground getting some traction.

Another trick that works sometimes is to apply the brakes and gas simultaneously with the traction control on...this starts a "stutter" of sorts with the ECM supplying power to alternate wheels.

I have actually done this on a 2005 Escalade AWD pulling a boat up a slippery ramp.

AWD systems cannot be "locked" as conventional 4 wheel drive can.

Never thought of those, will have to log that in the brain tank for future use!

 

[nharkey85]

Sorry, I'm not understanding this so appreciate some learning.. If one wheel is on ice, wouldn't it be like being off the ground? Shouldn't the other wheels take over?

With AWD power will unfortunatley flow to the wheels with least resistance (least traction)

 

[Hacksaw1981]

With AWD power will unfortunatley flow to the wheels with least resistance (least traction)

So one wheel in the back and one wheel in the front won’t spin ?