Differential whine - 2002 GMC 1500

I now (90K miles) have the exact same differential whine that was described in last Sunday’s (7/1/2018) article regarding the new Dodge pickup. My question is how do I determine which differential is making the noise??

I assume you have 4WD. You can assume it is the rear, as it gets the most use. I’d suggest someone riding in the bed to verify. Afterwards pull the rear diff cover and inspect by eye and feel.

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Thanks for the suggestion. Actually its All Wheel Drive, so I’m not sure if that still means the rear differential still does most of the work, or if it’s constantly changing back and forth??

Thanks for the reply.

Happy Fourth!

In a message dated 7/3/2018 6:25:34 PM Pacific Standard Time, cartalk@discoursemail.com writes:

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If it is the push-button variety AWD system where you can select 2WD or ADW or 4WD Hi and LO, it runs in 2WD most of the time until you push AWD. Even in AWD, the rear does most of the work since the front axle won’t even engage unless needed.

Consider that the transmission or power steering pumps also whine when worn and are far more likely to be the cause than a front or rear differential, especially at 90K miles.

Again, thanks for your interest.

It’s all wheel drive and engages whenever it senses the need - whenever that is.

No choice on my part.

The only choice that I do have is whether I want 2 wheel, or 4 wheel steering.

Also, just like in the article response - the whine only occurs when I apply enough pressure to the accelerator to maintain or increase hwy speed. As soon as I back off it stops.


In a message dated 7/4/2018 10:02:25 AM Pacific Standard Time, cartalk@discoursemail.com writes:

You have 4 wheels steering, too? The axle used or that system is the 3/4 ton Dana axle. It is way overkill for a 1500 truck but they chose to use that axle under both 1500 and 2500 trucks so they only had to tool one system. It could be the rear diff but it will take some sleuthing to find the cause of the whine.

Sounds like the pinion bearings have some play. Try moving the input U-joint to each differential up and down.