The digital radio receiver (DRR) receives XM satellite radio signals via 2 digital radio antennas located in each of the outside rearview mirrors. The antenna circuits are coaxial cables that carry the digital radio signal information received by the antennas to the DRR. The antenna coax also provides a path for voltage to power the antennas. Separate left and right audio signals (+) are sent from the DRR to the CD changer. The CD changer processes these signals and passes them to the audio amplifier.

When diagnosing digital radio concerns, the vehicle should be located outside with an unobstructed view of the southern sky to ensure proper reception of the satellite signal. Reception may limited, intermittent or not possible inside structures or under heavy cover.

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

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-48028 Digital Radio Test Antenna

1. Tune to a strong AM or FM station and verify each speaker is producing clear and even sound, with no distortion.

⇒	If any speaker is not producing sound or the sound produced is distorted, refer to Speaker Malfunction.

2. Ignition ON, verify communication with the DRR with a scan tool.

⇒	If the scan tool does not communicate with the DRR, refer to DTC U0100-U0299.

3. With the vehicle outside in an area with an unobstructed view of the southern sky, tune to XM. Verify XM reception is clear and the No XM Signal message is not displayed on the radio.

⇒	If the No XM Signal message is displayed or XM reception is poor, refer to Digital Radio Antenna Circuit Malfunction.

4. Radio tuned to XM, 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.

⇒	If either side of the vehicle is not producing sound or the sound produced is distorted, refer to Digital Radio Signal Circuit Malfunction.

Digital Radio Antenna Circuit Malfunction

1. Ignition OFF, disconnect the appropriate digital radio antenna coax from the digital radio receiver (DRR). Connect the EL-48028 to the DRR.
2. Ignition ON, radio tuned to XM, verify XM reception is clear and uninterrupted.

⇒	If reception is not clear, replace the DRR.

3. Ignition OFF, reconnect the antenna coax to the DRR, disconnect the digital radio antenna coax from the appropriate digital radio antenna.
4. Ignition ON, test for 4.5-5.5 volts between the antenna coax center terminal and the coax outer shield.

⇒	If not within the specified range, replace the antenna coax.

5. If all circuits test normal, replace the appropriate digital radio antenna.

Digital Radio Output Signal Circuit Malfunction

1. Ignition OFF, disconnect the X1 harness connector at the CD changer.
2. Ignition ON, radio ON and tuned to XM, test for a varying mV AC voltage reading between the following signal circuit terminals listed below and ground.

•	Left audio signal (+) - Connector X1, terminal 13

•	Right audio signal (+) - Connector X1, terminal 5

•	Audio common signal (-) - Connector X1, terminal 13

⇒	If the voltage reading is not as specified, test the signal circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the DRR.

3. If all circuits test normal, replace the CD changer.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.