AWD does yours make a noise when it engages

[Jr_454]

Hey all, I have a 2005 yukon 5.3 with all wheel drive. it is not a denali. When ever the front tires engage it sounds sort of like an air gun going off a very weird noise. I brought it to the dealership and they said that they were not sure if it was normal or not but they could find no wearing of parts or damage. Does any one else have this problem. Oh I live in minnesota and it really only seems to do it on ice if the rears cant get any traction. In deep snow or mud i never really hear it. Just hoping to get some thoughts. Thanks

 

[WoldD90]

Most of the trucks have the G80 rear-end, so it could be your rear locker or limited slip differential, they do make noise when they lock up.

 

[rigo_jones]

sounds like your front diff. its very common. you'll be ok for a while but remember to check the the diff fluid level. once the noise gets louder and you hear a grinding noise that means its about to go out.

 

[Clemsonbloz]

the true AWD is always engaged.. the rigs with the auto 4wd engages when it senses slip, so you might have that.. the awd is a 40 front 60 rear split, and is constant

 

[Jr_454]

Ok then I am confused because it is all wheel drive. The noise sounds like it is coming from the front of the dash or just behind the firewall. It only makes the sound if the rear wheels loose traction really fast. like trying to leave a stop sign on ice. If you are driving through snow it will make the sound for just a second and then it stops. if you are on ice it will keep making the sound until you have traction again. It almost sounds like the antilock brakes but really loud.

 

[jhellwig]

I also have awd on a tahoe. Mine also does the noise. It sounds like an air leak under the dash.

I think the front axle is vacuum operated. I think it just locks the front diff.

 

[afpj]

Are these the permanent AWD's? Is there a way to lock the diff ie 4 HI mode? If there is no way to lock the diff, it could be the antilock system as someone mentioned. I thought 03 and up AWD used the antilock's to retard wheel spin rather than a true mechanical diff like in the 02 that I have.

 

[Jr_454]

Im not sure if it uses the anti lock system it was just a thought, and yes jhellwig it does sound like an air leak. My truck doesnt have 4 hi but I can switch in to 4 lo. It would be interesting to see if any one knows if it is an anti lock system or if the front diff does lock. It is awd all the time unless I switch into for lo.

 

[jhellwig]

The stabilitrack system uses the breaks and throttle to control traction an wheel spin. When the stabilitrack is off, the manual still has traction control but I think it just has to do with activating the anti lock.

I am betting when you hear the noise under hard acceleration there is a traction acctive message on the dic. When you slide around a corner or crank the wheel while accelerating you get a stabilitrack active message and the noise.

When I turn the stabilitrack off and a hammer on it I also get the traction active message and the noise.

The feel of the way it drives seams to me like it is locking the front axle when you hear the noise. The stearing gets squirelier than a open diff 4wd. You can definitely tell that both front wheels are driving.

 

[Jr_454]

Jhellwig do you have the option to switch yours to 4 lo also. Are the Denalis awd and do they have the option for 4 lo also. Just wondering if there is a difference in are transfer cases. Are these AWD transfer cases weaker then the standard transfer case?

 

[jhellwig]

Mine also has a 4lo option. I assume that there is a differential in the transfer like other vehicles with awd.

 

[Clemsonbloz]

there is no shifting device on the front axle of the awd units.. It is a full time live axle

 

[Jr_454]

Isn't there the clutches that engage when it detects slipping in the rear wheels. and if there is no shifting how does it lock into 4 lo

 

[Clemsonbloz]

there are no clutches on the AWD... The auto 4wd has an auto engauge feature, but the awd is always live.. there is a viscous device in the transfer case from what I remember,, but there is no shifting, grabbing, ect.. The way you get into 4lo is to put it in neutral, and mash the bottom button on the pod to the left of your dash cluster.. That moves a motor in the t-case, and puts it into a reduction state..

the awd drive shaft turns all of the time, and the passenger side axle tube is void of a axle shift device.. There is no way to make the awd units 2wd, or selectable,, as if you removed the front drive shaft, you'd damage the viscous differental in the transfer case..

 

[208motors]

FYI I talked to an engineer at Borg Warner when I was thinking about a 6" lift on my '06 Denali xl. He informed me that the 4481 t-case in most Denalis has no clutch pack allowing the 2wd/4Hi and there is no planitary gear set witch gives 4Lo. The Denali has a viscus differential giving the 60/40 torque split but prevents binding in the drive train.

The purpose of my call to him was to discredit the claims that lifting a Denali causes "binding" in the drive train. Where it not for the front drive shaft angle and potential vibration, a Denali makes a great SUV to lift.

I can't speak for the noises but thought you might want to know some information I came buy while researching lift kits.

 

[DenaliAK]

Hey all, I have a 2005 yukon 5.3 with all wheel drive. it is not a denali. When ever the front tires engage it sounds sort of like an air gun going off a very weird noise. I brought it to the dealership and they said that they were not sure if it was normal or not but they could find no wearing of parts or damage. Does any one else have this problem. Oh I live in minnesota and it really only seems to do it on ice if the rears cant get any traction. In deep snow or mud i never really hear it. Just hoping to get some thoughts. Thanks

Dude, that is traction control kicking in. It's loud, scary sounding, and perfectly normal. Don't sweat it.

 

[Jr_454]

Thanks for the answers everyone. So we dont have clutch packs, Is it considered VLSD then. Sorry for all the questions. I have never had all wheel drive and am just a little confused as you can see. I did shut of the traction control DenaliAK and it did seem to help but I swear I heard it still just not as loud or as often.

 

[DenaliAK]

Even with traction control off, it still does kick on sometimes. I haven't quite figured that out myself. I think the whole stabilitrac system doesn't shut down. It'll let you spin the tires, but I think it might still activate the anti-lock brake portion of the system. It's not just an anti-spin mechanism, it's a whole system of brakes, drive-train, and steering adjustments. Obviously, some part of it is still in effect even with traction control off. I personally hate traction control and always turn it off, having grown up driving in the snow and reacting as needed to correct, it actually completely confuses my instinctive reactions.

 

[Jr_454]

It does do that. My wife drives it most of the time so its probably better for her. Its a nice ride, just wish I knew what the hell half the stuff is on this beast.