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Home >> Cadillac >> 2007 >> CTS Base, 2.8 T, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 220 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> Speakers Inoperative - One or More >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Center the balance and fade adjustment on the radio.
    • If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
  2. Listen to the audio using a normal radio frequency and then a digital radio frequency, listen for any inoperative speakers. If speakers only become inoperative when using the digital radio, disconnect harness connector containing the digital radio audio signals from the radio. Verify there is AC voltage present between the left and right audio signal circuits(+) and the audio common circuit (-).
    • If AC voltage is not present test for an open, short to ground or short to power on the audio signal circuits and the audio common circuit between the radio and the digital radio receiver (DRR). If all circuits test normal, replace the DRR.
    • If AC voltage is present, replace the radio.
    3. IMPORTANT: If the vehicle is not equipped with an amplifier skip step 3 and 4.
  3. Disconnect the harness connector at the amplifier that contains the suspect inoperative channel. Connect a DMM between the suspect low level audio signal circuits. With the scan tool, perform the radio tone test on the suspect speaker channel and verify there is an AC voltage and not DC 12 V.
    • If the suspect speaker channel low level audio signal AC voltage is 0 V AC or 12 V DC, test or repair open, short to ground or short to power on the suspect speaker channel low level audio signal circuits. If a open, short to ground or a short to power can not be found, replace the radio.
  4. Reconnect the amplifier harness connectors.
  5. Disconnect the harness connector of the suspect speaker. Connect a DMM to between the suspect speaker signal circuits at the speaker harness connector. With the scan tool, perform the amplifier tone test on the suspect speaker channel and record the AC and DC voltage. Verify there is an AC voltage and not DC 12 V.
    • If the suspect channel speaker signal AC voltage is 0 AC or 12 V DC, test or repair open, short to ground or short to power on the suspect speaker channel signal circuits. If a open, short to ground or a short to power can not be found, replace the amplifier if equipped. Replace the radio if not equipped with an amplifier.
    • If the suspect speaker channel signal circuits test normal, Replace the suspect speaker.
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