1

1. Turn the ignition switch to the ACC position.
2. Turn the radio ON.
3. Select a strong radio station.
4. Set the volume control to mid-level.

Radio display illuminates and sound is heard from speakers.

2

1. Turn the FADE control to the front speakers.
2. Turn the FADE control to the rear speakers.
3. Return FADE control to the neutral position.
4. Turn the BAL control to the left side speakers.
5. Turn the BAL control to the right side speakers.
6. Return BAL control to the neutral position.

1. Only front speakers are heard.
2. Only rear speakers are heard.
3. Front and rear speakers are heard.
4. Only left side speakers are heard.
5. Only right side speakers are heard.
6. Left and right side speakers are heard.

3

1. Adjust BASS control to the high and low position.
2. Adjust TREB control to the high and low position.
3. Return BASS and TREB control buttons to the neutral position.

1. Music attenuates between high and low bass frequencies.
2. Music attenuates between high and low treble frequencies.
3. Music returns to nominal bass and treble frequencies.

Audio Preliminary Diagnosis

4

1. Turn the Headlamp Switch to the PARK Position.
2. Adjust the dimming switch the maximum intensity and then to the minimum intensity.

Radio display and the buttons illumination intensity varies.

Radio Display Does Not Dim with Instrument Panel Dimmer Switch

5

1. Place a cassette tape in the tape player¹.
2. Operate all of the available features.
3. Eject the cassette tape.
4. For remote cassette tape player¹:

4.1.	Turn the Headlamp Switch to the PARK Position.

4.2.	Adjust the dimming switch the maximum intensity and then to the minimum intensity.

6

1. Play a compact disc (CD)¹.
2. Operate all of the available features.
3. Eject the CD.
4. For remote CD player¹ (except Envoy):

4.1.	Turn the Headlamp Switch to the PARK Position.

4.2.	Adjust the dimming switch the maximum intensity and then to the minimum intensity.

7

1. Connect headphones to the rear seat audio module².
2. Select REAR DSPL function on the radio.
3. Operate all the available features.
4. Place the headlamp switch to the PARK position.

8

1. Turn the speed compensated volume switch¹ to the MAX position.
2. Test drive the vehicle.

Audio amplification varies with vehicle speed.

Speed Compensated Volume

9

Operate the dealer installed phone/onstar system³.

Radio mutes the front door speakers during phone/onstar operation.

Radio Always/Never Muted

10

No abnormal results where found while performing the System Check.

The system is OK.

Intermittents and Poor Connections Diagnosis

* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.

¹ Denotes optional equipment.

² Denotes Envoy only.

³ Denotes Envoy only optional equipment.