GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Corvette 🢒 Accessories 🢒 Entertainment 🢒 Speakers Inoperative - All

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit Description

The amplifier receives four channels of low level audio from the radio. The amplifier is powered by a dedicated B+ and ground circuit but the amplifier is only powered ON when the radio supplies a voltage on the antenna enable signal circuit. The amplifier can be commanded to mute audio signals when supplied with voltage on the amplifier mute signal circuit from the radio.

Reference Information

Schematic Reference

Radio/Audio System Schematics

Connector End View Reference

Entertainment Connector End Views

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Testing
  1. Ignition ON and radio ON, Center the balance and fade adjustment on the radio and increase the volume.
    2. ⇒If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
  2. Ignition OFF, disconnect the amplifier C1 harness connector.
  3. Test for B+ on terminal H (U65) or E (US8/U66) .
    4. ⇒If less than specified voltage repair short to ground or open high resistance.
  4. Disconnect amplifier harness connector C2 if equipped with Y07 or US8/U66.
  5. Ignition ON and radio ON, test for less than 1 volt on the amplifier mute signal circuit terminal A8 (US8/U66) or B1(U65).
    6. ⇒If greater than 1 volt repair short to B+ or replace the radio.
  6. Test for greater than 9 volts on antenna enable signal circuit terminal A3 (US8/U66) or B11(U65).
    7. ⇒If less than specified value, repair short to ground or open/high resistance or replace the radio.
  7. Ignition OFF, test for less than 1 ohm between the amplifier ground circuit terminal F (US8/U66) or A (U65) and ground.
    8. ⇒If greater than specified value repair open/high resistance.
  8. Disconnect the amplifier C2 harness connector if equipped with Y67.
  9. Ignition ON and radio ON, center the balance and fade adjustment on the radio and increase the volume.
  10. Test for AC voltage between the left front low level audio signal (-) terminal A6 (US8/U66) or B9 (U65) and left front low level audio signal terminal (+) A7 (US8/U66) or B10 (U65) .
    11. ⇒If AC voltage is not present replace the radio.
  11. If all circuits test normal replace the amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for amplifier and radio replacement