02 - 04 Buick , Chevrolet , GMC and Oldsmobile Mid-Sized Utilities: Automatic Volume Feature Diagnosis on UQA Bose Radio - kw inoperative operation noise GMT360 GMT370

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Automatic volume feature diagnosis on the UQA BOSE radio

"Auto Vol" on the UQA (BOSE) radio works much differently that the "Speed Compensated Volume" (SCV) system on non-UQA radios. The sensor is located on the passenger side of the overhead console and works on about 1-3 mV.

Feature operation can be tested as follows:

1. Set the radio volume at the 2 or 3 bar mark on the display.
2. Drive the vehicle at 50 mph.
3. Depending on the area, there are 2 types of driving conditions to verify the operation.

•	Turn the HVAC blower on medium to high with the windows closed

•	Drive down a dirt road, all windows closed.

4. Turn the auto volume feature ON & OFF while the blower is on or while driving down a dirt road. Pause for a moment after each depress of the button. There should be a subtle but noticeable difference.

With the system ON, the dynamic equalization is changed to compensate for background noise. The sound quality difference will be more noticeable at lower speeds. There is NO input from the vehicles speed sensors. This system will not compensate for louder noise levels. Example; Driving on the express way with the window open. Reference the Owners manual for further details.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(2002-2004 Chevrolet Trailblazer and Trailblazer EXT) and (2002 - 2004 GMC Envoy and Envoy XL) and (2002 - 2003 Oldsmobile Bravada) and (2004 Buick Rainier)

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