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Digital Radio Poor or No Reception

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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+ Voltage

--

1

-

-

Left Audio Signal (+)

2

2

2

-

Left Audio Signal (-)

2

2

2

-

Right Audio Signal (+)

3

3

3

-

Right Audio Signal (-)

3

3

3

-

Digital Radio Aerial Coax Signal

B1259 02

4

4

-

Ground

--

1

-

-

1. No communication with Digital Audio Broadcast module.

2. No or distorted audio from left side speakers when listening to digital radio.

3. No or distorted audio from right side speakers when listening to digital radio.

4. Poor or no reception with Digital Audio Broadcast.

Circuit/System Description

The Digital Audio Broadcast (DAB) radio receiver receives a digital radio signal via the digital radio aerial. This signal is passed to the DAB module through the digital radio aerial coax. The DAB module sends a varying AC mV signal through separate left and right audio circuits (+ and -) to the radio. The voltage amount and rate of change is dependent upon the type of signal being received. The radio then processes these signals and passes the audio to the amplifier.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Component 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

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-48028 Digital Radio Test Antenna

Circuit/System Verification
  1. Tune to a strong AM or FM station and verify each speaker is producing clear and even sound, with no distortion.
    2. ⇒If any speaker is not producing sound or the sound produced is distorted, refer to Speaker Malfunction .
  2. With the vehicle outside in an area with an unobstructed view of the southern sky, tune to Digital Audio. Verify reception is clear.
    3. ⇒If reception is poor, refer to Digital Radio Aerial Circuit Malfunction.
  3. A11 Radio tuned to Digital Audio, use the radio balance function to transfer audio between the left and right side of the vehicle. Verify clear and even sound is heard from each side of the vehicle.
    4. ⇒If either side of the vehicle is not producing sound or the sound produced is distorted, refer to Digital Radio Output Circuit Malfunction.

Circuit/System Testing

Digital Radio Aerial Circuit Malfunction

  1. Ignition OFF, disconnect the aerial coax from the A12 Digital Radio Receiver Control Module. Connect the EL-48028 to the A12 Digital Radio Receiver Control Module.
  2. Ignition ON, radio tuned to digital radio, verify reception is clear and uninterrupted.
    3. ⇒If reception is not clear, replace the digital radio receiver.
  3. Ignition OFF, reconnect the aerial coax to the A12 Digital Radio Receiver Control Module, disconnect the digital radio aerial coax from the T4H Digital Radio Aerial.
  4. Ignition ON, test for 4.5-5.5 volts between the aerial coax centre terminal and the coax outer shield.
    5. ⇒ If not within the specified range, replace the aerial coax.
  5. If all circuits test normal, replace the T4H Digital Radio Aerial.

Digital Radio Output Circuit Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the A11 Radio.
  2. Ignition ON, radio ON and tuned to digital radio, test for a varying mV AC voltage reading between the following signal circuit terminals listed below and ground.
    3. • Left audio signal (+) - terminal 22
    • Left audio signal (-) - terminal 8
    • Right audio signal (+) - terminal 21
    • Right audio signal (-) - terminal 7
    ⇒If the varying mV AC voltage is not present, test the signal circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the A12 Digital Radio Receiver Control Module.
  3. If all circuits test normal, replace the A11 Radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio and digital audio broadcast module replacement, setup, and programming

   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved