Happy New Years to all!

My son describes the symptom as a low, vibrating noise when he accelerates from a stop. The vibration goes away once he gets past 10-15 mph.

We learned that he had the "Auto" 4WD button switched ON (located on the left side of the dash). Once we switched it off, the vibrating stopped.

For now, as long as he doesn't use the "Auto" 4WD button and keeps the "2WD" button pressed , the truck functions normally.

Has anyone experienced this symptom before? When I test drove the Tahoe to experience the symptom, I can feel the transmission or 4WD trans component shaking, vibrating.

I'm hoping that he's not ruined any of the 4WD components.

Thanks in advance for any & all replies!

 

Are the tire sizes the same on all four corners? It is possible that there's issues with the transfer case...

The switch being on wouldn't cause the issue, as it's an automatic system.

 

Thanks for your comments. Yes, the tires are all the of same brand, size. Balanced, rotated regularly.

As I suspected per your "transfer case", is there a method, service, technique or way to check the TC out?

V

 

After re-reading the post, I realized I forgot to mention the hubs. The motor may not be locking the hubs properly too.

Best to take it to a shop for better diagnosing. I've owned electronic 4X4 in the past, but only recently got back into them. I've been dealing with manuals for the last 10 years. Heck, I pulled the electric hubs off of my Exploder and put manual locking hubs in due to problems we were having with it.

 

Your going to naturally to have a very small amount of vibration when in auto FWD because this mode engages the front axle but not the transfer case until the system senses slippage. With the front axle engaged you are now turning the gears and all the u-joints in the front drive. What you describe almost sounds normal from what I've seen from this type of system.

 

My 99 Suburban does the same thing. I only engage Auto when on snowy roads or sometimes on the beach.

 

Hi, just reading this topic due I am having the same issue on my 2003/04 Z71 Burb. So I would like to ask, were are the hubs? Can anyone post a photo of it for me or describe it?
Unfortunately (or fortunately), I live in Brazil, and GM of Brazil does not fix this car here because it is not sold by them, so I have to make the mechanic by myself.
Thank you all,
Sergio

 

Ha, here I go again, harping on vehicle maintenance. :biggrin:

It's highly possible that your front Differential is just crudded up, from lack of regular Fluid Changes. With most of our vernicles, a certain amount of "noise" can be herd, when engaging the 4WD. The vibrations you seem to have could be coming from just dirty old Fluid (lack of proper lubrication).

I'd first try a Fluid Change. You probably should do that for the Transfer Case and rear Differential as well.

Once having fresh Fluids installed, it's a very good practice to place your vehicle in 4WD-hi and lo with regularity (like once a month) to keep the Fluid circulated and systems able to work/change more smoothly.

 

Hi SwHouston,
Thank you for the reply. Well, I have already changed the oil of the front axle, rear axle, automati transmission and engine on the past month, but... I haven't turned on the 4WD Hi or Lo since I bough the car on March of this year. Well, today I have engaged the 4WD Hi and Lo and it looks fine.
One thing I have found on my car that the rear wheels had untightened bolts. Well, I hope I have solved my problem.
Thank you,
Sergio

 

Hello Sergio, it's nice to see you back on the Forum again.

Good for you, doing good maintenance on your Ride. That's the key to making them last and perform well.
Yes, one has to check everything when buying a Used Vehicle. People don't care about them, when they're getting another.
Be sure to use the 4WD-lo often. The changing back and forth is what keeps them able to change well, not so much as how far you drive in the Lo Range.

Again, welcome back, and have a good Day !