Deceleration noise

06-21-2004, 01:42 PM
On occasion when I take my foot off the accelaerator after cruising above 60 mph, and before I touch the brake, my 01 Jimmy starts making a loud whining/humming noise. In the past I have toggled between the 2 WD and 4 WD buttons and this has stopped the noise. Last night when I tried it only quieted the noise for about 10 seconds and then it started humming again.

I have had the truck to my local GMC dealer about 4 times and they can't find anything since when I pull in, of course, the noise never happens. Thanks for any help.

06-21-2004, 03:37 PM
Hey, I'm getting the same thing in my '94. The 2WD/4WD seems to do the trick temporarily too. At first, I thought it was the brakes. I have yet to take it to the shop. Let me know what you find out. Maybe take it while it's doing it and take the mechanic out for a ride too.

06-28-2004, 11:29 AM
It could be the front differential. Did you notice any leaking fluid?

07-06-2004, 04:54 PM
It could be the front differential. Did you notice any leaking fluid?

Turned out to be the 4WD acuator vacuum switch that was sticking occasionally that I read about in an earlier post here. Whole job cost less than $70 at the dealer.

07-06-2004, 05:09 PM
Thanks for the input. That seems to be the consensus.

07-06-2004, 05:21 PM
my 95 makes a chattering noise when coasting under speeds of 20 MPH.
It's not there when im in 4WD.

Im pretty sure its the 4WD drive shaft.....the piece that goes into the transfer case?

sound familiar?

12-08-2004, 10:34 PM
I had the same problem except after I put on the brakes on Id hear a clunck and the sound would go away, when I it the button for 4wd I can hear what sounds like a gear sliding over but 4wd never engages

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