Hello, you may want to take a look at this bulletin from GM concerning belt noise and see if it helps you. Thanks
Some customers may comment on a whining-type noise that is audible in the vehicle's passenger compartment. This noise can typically be heard when the vehicle is idling and may vary in pitch as engine RPM is increased.
The power steering (PS) pump pulley may be positioned too far inboard on the PS pump.
Inspect the PS pump pulley for proper positioning on the PS pump shaft. If it is determined that the pulley is not even/flush with the end of the shaft (+/- 0.25 mm (0.010 in) following the applicable Service Manual procedure and using J 25034-C, reposition the PS pump pulley.
For vehicles repaired under warranty, use:
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