Four Wheel Drive Problem - Maybe

Hey guys. New member here.  I'm hoping that someone can help me out with my four wheel drive.  This may get lengthy but I want to be thorough. 
I have a 2004 Avalanche Z71.  Last weekend I had to drive through my yard and hit a really muddy spot and got stuck.  I put the truck in 4 hi and still couldn't get out.  Got out and looked at the truck and noticed there was no mud on the front inner fenders.  Next day I used my trusty 98 Jeep GC to pull it out. My truck sits through the week.  Not a DD.
Since the lights changed to 4 hi, and I could hear the motor moving in the TC, I assumed it was the front axle actuator not engaging.  Yesterday I jacked it up, removed the skid plate, and removed the actuator.  I had my dad press the 4 hi button while I stayed under the truck.  I could hear the motor turn in the TC, and then the actuator popped out about an inch, maybe a bit more.  So then we jacked it up on four jack stands to test everything out.  Reinstalled actuator.  Started it up, shifted into drive and the driver side rear wheel was spinning.  Not sure about passenger - me and my dad never looked.  I pressed the 4 hi button, the lights changed to indicated 4 hi, I heard the servo motor, but no movement on the front wheel.  Once I hit the brakes and released, the drivers side front wheel began to spin.  I pressed the 2 hi button, heard everything move, and the front wheel slowed down and stopped.  Pressed the 4 hi button, tapped the brakes, and the front wheel begins to turn.  My dad held a 2x4 up to the tire to try to stop it and couldn't.  All indication point to the 4 wheel drive working.
I drove home and hit the 4 hi button upon entering my driveway.  It is a slight incline and covered in snow.  The truck wouldn't make it up. I stood out on the running board pressing the gas and the front wheel would not spin. Does anybody know what is going on?     

Sounds like it 's working..

When you put it into 4 high you should be driving down the the road for it to engage. It's not instantaneous and can take 10-20 seconds. It's not like locking hubs where you just jump out and lock them in and go, there needs to be some rotation in the drive train. It will eventually work but may take longer when your at a stop.. If your going to put yourself into a situation where you may need 4 wheel drive then you should engage it before you need it.

Did you try 4 Low?

I did not try 4 lo.
I've never had an electronic shift 4x4.  I've only had my Avalanche for about 6 months.  My Jeep works immediately after I shift but it is a manual lever and the front differential does not have an additional actuator.  I have to be stopped and in neutral before I can move the lever. 
I assumed that since you can shift these trucks on the run (maybe it's required?) that there is a delay for everything to get meshed and rolling.  I think you verified my assumption.  I will need to shift into 4x4 as a preparation until waiting until it is too late.

4 high at any speed and 4 low under 5 mph but there's a delay.. Read the manual in the Resources section...

on my 03 z71 I've always stopped, put truck in natural, and selected 4x4 low or high. Never had any problem , do not know if that is required for it to engage 

Is there such a thing as a weak actuator or is it as simple as it either works or doesn't work?  It popped out pretty quick and I noticed that it is spring loaded.  Just wondering if the spring is too weak to keep the gears meshed together?  I could push it in slightly by hand.  I know the front was spinning while in the air so I assume it would spin even under a load from the weight of the truck.

Resurrecting an old thread since I started it.

Four wheel drive is still not working.  I had to drive home last night in an awful freezing rain in west central Ohio.  I had it in 4 Hi all the way home, driving 25MPH for 50 miles.  The back end constantly was sliding out from behind me.  I got home and couldn't make it up my driveway.  Luckily, it should warm up today and melt it.

Anyways, this morning I looked into it.  I can press 2wd or 4 hi.  I can hear the motor change in the transfer case.  I can then hear the actuator in the front differential.  Lights on the buttons stay on after the change.  No red or unneccesary blinks.  I shifted the transfer case into neutral, and that works.  I just cant get any power to the front wheels.  Tried shifting into 4 hi on the go, in park, in neutral, everything.  Tried waiting in case it just needed more time.  Tried going backward first to get stuff to engage.  Still out there on the ice I cannot get the front wheels to grab. 

I'd like to ask why you have not tried or mentioned very much about using 4 Low? As mentioned, the front axle does not have a Locker.

To engage 4 Low, the vehicle should be stopped or moving less than 5 mph, and Gear
Selector in Neutral. You'll hear some mechanical nosie and possibly feel some vibration in the seat of your pants. When you shift to Drive, you'll immediately see the higher RPMs as you do with your other 4x4.

It would be odd for 4 Low to work and not 4 High.

Then next area to search for is Pump Rub in the Transfer Case and/or Boot leaks in the Front Axle.

I'm not a gear head but have been driving GM 4x4's with the silly incarnations of the Front Axle Actuator since 92. Before, that, I drove a 75 K5 Blazer for 17 years that was Full time 4x4 that I changed out to Warn Hubs and was Direct Shift Engagement for both High & Low 4x4.

I busted the guts out of my CV axle, drivers side, last year at the dunes.  Not sure why yours isn't working, but that caused all my 4x4 to go out, both hi and low.

Have you tried 4low?  See what happens. 

I did try 4 lo on Friday night after sliding off the road near my driveway.  I felt/heard the 'clunk' but the front wheels would not drive and I was still stuck.  Had to have my 98 Jeep GC pull it out and onto the driveway.
The ice storm we had on Friday night was horrible.  Yielded almost 1/4" of ice at my place.  I can't get the Avalanche up my drive way as the rear wheels just spin.  The Jeep pulled the Avalanche out of the ditch and it was sitting on ice. 

From my non Gear Head experience & perspective, no offense to those with the great mechanical knowledge that I do not possess, it does sound like a disconnect between the transfer case and the front axle. Too bad it it is not a simple answer.

As mentioned above this post, there could be a number of things going on to block out the 4x4 from working until an item or items are repaired or replaced.

Have you checked the front axle boots for tears and leaks? In Neutral on both the Column Indicator and 4x4 Selector Dial, can you turn the drive shaft by hand? Then again in 1 or both of the gear positions? Please place blocks properly to keep the Avalanche from rolling while trying to do this. I'm sure the weather and temps are just ideal for crawling around under the rig right now.

This always seems to happen when we need it most.

Someone with more mechanical knowledge should be chiming with further information.

have someone else look at a few things while you are trying to get up your driveway.
Is the front driveshaft spinning? If so, can you see either of the front axel shafts spinning?

Have you cheacked your transfer case fluid level?

Putting it into 4 wheel drive on ice will make it a roller skate. Put it into auto mode and it can figure out what wheel has the most traction. The AV weighs 6,000 pounds it's not a jeep.

What tires do you have on it.

seipel1892 said:

I did try 4 lo on Friday night after sliding off the road near my driveway.  I felt/heard the 'clunk' but the front wheels would not drive and I was still stuck.  Had to have my 98 Jeep GC pull it out and onto the driveway.
The ice storm we had on Friday night was horrible.  Yielded almost 1/4" of ice at my place.  I can't get the Avalanche up my drive way as the rear wheels just spin.  The Jeep pulled the Avalanche out of the ditch and it was sitting on ice.  

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The transfer case actuator (encoder motor) may be fine, but that doesn't mean something isn't broken inside the case.

Here's one of the more coherent videos on how to think about troubleshooting 4-wheel drive.  The technician goes where the evidence leads:

Diagnosing 4-Wheel Drive

Since yours is an '04, pay close attention to the end.

Got it fixed yesterday, but I didn't do it.  I had to take it to a mechanic that I actually trust.  He chalked it up to a weak motor on the transfer case.  He installed a new one and charged 2 hours labor.  When I got home I started to slip going up the driveway.  Hit the 4hi button and it grabbed and took me right up.  I did a little research last night and this is not uncommon.  The motor can keep the truck in 4x4 when up on 4 jack stands but not under load when it is down on the ground.  I know from the PO that the motor was replaced once before, but it could have been a cheap aftermarket unit. 

Well done!

So, I put the '08 through it's paces, this week.  Freezing rain, ice, snow, -5 Fahrenheit - you name it.

Everything normal in Auto & 4-wheel Hi.  Seems to slip in 4-wheel Lo.  Also, could only get transfer case into Neutral, once.  Not sure what to make of it, yet.

Will use my DiabloSport to remove the firm shift option, then diagnose over the weekend.

MS03 2500 said:

Putting it into 4 wheel drive on ice will make it a roller skate. Put it into auto mode and it can figure out what wheel has the most traction. The AV weighs 6,000 pounds it's not a jeep.

What tires do you have on it.

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Don't mean to do this but I crashed my other 4x4 vehicle into a retaining wall on a bridge two days ago when I hit a patch of ice, and I wasn't even speeding at 35 mph. I didn't have it in 4wd and the rear end came out from under me, swerving right into the right retaining wall in my lane then careening off towards the left retaining wall in opposite traffic, where I hit it head on and came to rest, airbags deployed and gave me a bloody nose but no worse, thankfully.  Also luckily no one in opposite traffic hit me, or more accurately, vice-versa.  I was wondering had I had it in 4WD the whole time if I would have experienced the same once I hit the ice, or if it would have helped avert it.  Either way, the vehicle is totalled    And for now I am driving the Av daily, but ironically the 4WD isn't working on it either similar to the OP's issue.

ngrome said:

Don't mean to do this but I crashed my other 4x4 vehicle into a retaining wall on a bridge two days ago when I hit a patch of ice, and I wasn't even speeding at 35 mph. I didn't have it in 4wd and the rear end came out from under me, swerving right into the right retaining wall in my lane then careening off towards the left retaining wall in opposite traffic, where I hit it head on and came to rest, airbags deployed and gave me a bloody nose but no worse, thankfully.  Also luckily no one in opposite traffic hit me, or more accurately, vice-versa.  I was wondering had I had it in 4WD the whole time if I would have experienced the same once I hit the ice, or if it would have helped avert it.  Either way, the vehicle is totalled    And for now I am driving the Av daily, but ironically the 4WD isn't working on it either similar to the OP's issue.

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You may have had better results in 4-wheel Auto, but hard to tell.

You encountered ice on a bridge, which is one of the worst circumstances.  

Stability control, by itself, may have yielded the best results.  4-wheel Hi, the worst.

Glad you got it fixed.