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. |
DTC Descriptors
DTC B125A: Antenna 1 Circuit LeftDTC B125B: Antenna 2 Circuit Right
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
B+ Voltage | 1 | 1 | -- | -- |
Ground | -- | 1 | -- | -- |
Left Audio Signal (+) | 2 | 2 | 2 | -- |
Right Audio Signal (+) | 3 | 3 | 3 | -- |
Audio Common Signal (-) | 4 | 4 | 4 | -- |
Left Digital Radio Antenna Coax | B125A, B1259 | B125A, B1259 | B125A, B1259 | -- |
Right Digital Radio Antenna Coax | B125B, B1259 | B125B, B1259 | B125B, B1259 | -- |
1. No communication with DRR/XM not available 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. No or distorted audio from all speakers when listening to digital radio | ||||
Circuit/System Description
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.
Conditions for Running the DTC
| • | Ignition ON. |
| • | Battery voltage must be between 9-16 volts. |
Conditions for Setting the DTC
B125A
The DTC will set when the DRR detects a short to voltage, short to ground, or an open/high resistance in the antenna 1 circuit.
B125B
The DTC will set when the DRR detects a short to voltage, short to ground, or an open/high resistance in the antenna 2 circuit.
Action Taken When the DTC Sets
| • | Digital radio reception may be poor or not available. |
| • | The radio displays "No XM Signal" or "Check Antenna". |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Radio/Navigation System Schematics
Connector End View Reference
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
Circuit System Verification
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.
Circuit/System Testing
- Ignition OFF, disconnect the appropriate digital radio antenna coax from the digital radio receiver (DRR). Connect the EL-48028 to the DRR.
- Ignition ON, radio tuned to XM, verify DTC B125A/B is not current.
- Ignition OFF, reconnect the antenna coax to the DRR, disconnect the digital radio antenna coax from the appropriate digital radio antenna.
- Ignition ON, test for 4.5-5.5 volts between the antenna coax center terminal and the coax outer shield.
- If all circuits test normal, replace the appropriate digital radio antenna.
| ⇒ | If the DTC is current, replace the DRR. |
| ⇒ | If not within the specified range, replace the antenna coax. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for DRR replacement, setup, and programming |
