I have a 2003 2500HD 4wd 4 speed automatic 47000 miles.I just picked it up so I am unsure if this is normal or not. I hear a whistling noise coming from it whenever it is in gear. It almost sounds like a noise a slightly cracked open window or vaccuum leak would makeIt is very light and high pitched whistle. It will go away when I put it in neutral andcome right back in any gear. Shifting is fine fluid isnew and trans temp stays OK. Is this anything normal? Granted my dog-like ears picked it up when no one else's could until I mentioned it. Maybe that is why they put the Bose speakers in it? Any help would be great. All in all I'm happy to be back in a Chevy after driving an oval for a while, but I have been out of the loop on the tech side.

 

No thats not normal. Mine doesn't do that. That dose make me wounder what was there reson for changing the tranny fluid though. Bose steeros are an option in 03 .

 

I don't think there was any conspiracy reason for the dealership changing the fluid. They changed all the fluids as part of the Certified Pre-owned thing. I am not entirely concerned as it has a warranty, but I'd rather not have to deal with it if it is something simple.

 

a lil food for thought here, just because it is a certified pre-owned truck does not mean they are lookin for your best interest.I have experienced trucks that were certified but had no actual work done to them. Ex:they said the oil was changed with new fluid, but after only a week and a halfwhen i did an oil change myself there was no oil in the engine just sludge... they lied. As to your's,they might have put new fluid in the tranny to cover up something wrong, so to someone without any knowledge might think that "hey, its new fluid so it has to be good". Truth is flushing a tranny can sometimes ruin it, not always true thoughas there is no two parts identical. They all have different outcomes. One may run forever with no problems where as one might go 2,500 miles and has to be replaced.Pending on how much dirt is in the fluid when you rinse It out the clearances become larger from the dirt being removed causing the transmissions to work poorly and start to fail.I would recommend taking it to a trusted mechanic and have him check it. and BTW my tranny does have a wine to it, but its just a normal drivetrain wine from the gears when accelerating... best of luck