B1259

DTC B1259

Diagnostic Instructions

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

DTC Descriptors

DTC B1259 02
- Antenna Ground Circuit Short to Ground

DTC B1259 05
- Antenna Ground Circuit Short to Battery or Open

Circuit/System Description

The digital radio receiver (DRR) receives digital radio information from a specific digital radio antenna located on the outside of the vehicle. The DRR is connected to the digital radio antenna via a shielded antenna coax cable.

Conditions for Running the DTC

This test is run every 300 milliseconds.

Conditions for Setting the DTC

The DRR detects an antenna fault.

Action Taken When the DTC Sets

The radio displays "No XM Signal" or "Check Antenna".

Conditions for Clearing the DTC

* The condition for setting the DTC is no longer present
* The DTC clears after 100 malfunction-free ignition cycles

Circuit/System Verification

1. Contact XM at 1-800-852-9696 to verify customer account status or possible network problems.
2. Ensure the vehicle is outside in an area with an unobstructed view of the southern sky. Turn ON XM radio. Tune the radio to satellite channel 1. Reception should be clear.

Circuit/System Testing

Important: Check for the proper operation of the OnStar(R) System prior to performing this diagnostic. Address any concerns with the OnStar(R) System prior to diagnosing or repairing the XM radio concern.

1. Ignition OFF, disconnect the antenna coax from the DRR. Connect the EL-48028 to the DRR and place on the roof of the vehicle.
2. Ignition ON, radio tuned to XM. Verify XM reception has improved.

• If the reception is not improved, replace the DRR.

3. Ignition OFF, disconnect the antenna coaxial from the digital radio antenna.
4. Test for less than 5 ohms of resistance end to end at the coax center conductor.

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

5. Test for less than 5 ohms of resistance end to end at the coax outer shield.

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

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

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Digital Radio Antenna Cable Replacement
* Cellular Communications/Digital Radio Antenna Replacement
* Control Module References for DRR replacement, setup, and programming