The digital radio receiver (DRR) receives an XM satellite radio signal via the digital radio antenna. This signal is passed to the DRR through the digital radio antenna coax. The DRR 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 appropriate speakers or 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 be 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. 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.

3. 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 digital radio antenna coax from the digital radio receiver (DRR). Connect the EL-48028 to the DRR and move the vehicle outside in an area with an unobstructed view of the southern sky, tune to XM.
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 digital radio antenna.
4. Ignition ON, test for 4.5-5.5V 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 digital radio antenna.

Digital Radio Output Circuit Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the radio.
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 (+) - terminal J

•	Right audio signal (+) - terminal H

•	Audio common signal (-) - terminal K

⇒	If the varrying mV A/C voltage reading 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 DRR.

3. If all circuits test normal, test or replace the radio.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.