B125B

DTC B125A or B125B

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC B125A
- Antenna 1 Circuit Left

DTC B125B
- Antenna 2 Circuit Right




Circuit/System Description

The antenna signal circuits are coaxial cables that carry the radio signal information received by the driver and passenger digital radio antennas. The antenna cables also provides a path for DC current for powering each antenna. The antenna 1 circuit (left) is the green connector at the digital radio receiver (DRR). The antenna 2 circuit (right) is the curry colored connector at the DRR.


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 (Radio/Navigation System Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Radio/Audio System Description and Operation (Radio/Audio System Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

EL-48028 Digital Radio Test Antenna


Circuit/System Testing

Important:
* Ensure the vehicle is outside in an area with an unobstructed view of the southern sky. Turn XM radio ON. Tune the radio to satellite channel 1. XM reception should be clear.



1. Ignition OFF, disconnect the appropriate antenna coax harness connector at the DRR.
2. Connect the EL-48028 to the DRR and place it on the roof of the vehicle.
3. Ignition ON, radio tuned to XM, verify XM reception has improved and DTC B125A/B is not current.

• If the XM reception has not improved and DTC B125A/B is still current, replace the DRR.

4. Ignition OFF, disconnect the antenna coaxial cable from the DRR antenna base.
5. Test for less than 5 ohms between the two ends of the coax cable center conductor.

• If greater than the specified range, replace the antenna coax cable.

6. Test for less than 5 ohms between the two ends of the coax cable outer shield.

• If greater than the specified range, replace the antenna coax able.

7. Test for infinite resistance between the antenna coax center conductor and the outer shield.

• If less than the specified range, replace the antenna coax cable.

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



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Digital Radio Antenna Cable Replacement (Digital Radio Antenna Cable Replacement)
* Mirror Replacement (Mirror Replacement)
* Control Module References (Programming and Relearning) for DRR replacement, setup, and programming