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2002 chevy trailblazer_ltz
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11 Posts
Discussion Starter · #1 ·
Just switched my 02 Trail Blazer, 56K, into 4WD while in Park. When I began to travel down the road noise sounded similar to travelig over small speed bumps in road. Noise did not present itself when in 4WL or 4WH. There was no grinding or orther severe abnormal noises, and the car drove fine. The tranny nor the 4WD have had any mainteneance or work on them. Any information will be appreciated.

Steve
Maryland
 

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2004 gmc
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26,181 Posts
You mean A4WD mode? Very very odd. In A4WD mode, the clutches in the transfer case aren't touching hard, the way they are in 4HI or 4LO, but they should be spinning the same speed while on pavement.

The TC fluid change interval is 50K, so that's the first thing to do if you're over that mileage. Get two quarts of GM Autotrac II fluid, and check what drains out for amount and particulates.

First report since I've been here of anything quite like that. Welcome!
 

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2003 gmc envoy_slt
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7,190 Posts
I had that same type of sensation with mine. Mine was more of a feeling than a noise. If I changed to 2HI or 4HI while driving in A4WD, it went away. Changed the transfer case fluid and the problem was gone. I changed mine at 36k.
 
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