For 1990-2009 cars

### 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 Descriptor

DTC B1259: Antenna Ground Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
B+ Voltage | -- | 1 | -- | --
Left Audio Signal (+) | 2 | 2 | 2 | --
Right Audio Signal (+) | 3 | 3 | 3 | --
Audio Common Signal (-) | 4 | 4 | 4 | --
Digital Radio Antenna Coax | B1259 | B1259 | B1259 | --
Ground | -- | 1 | -- | --
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 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.

### Conditions for Running the DTC

Ignition is ON.

### Conditions for Setting the DTC

DRR detects an antenna fault.

### Action Taken When the DTC Sets

Radio displays No XM™ Signal.

### Conditions for Clearing the DTC

• | A current DTC will clear when the conditions for setting the DTC are no longer present.

• | A history DTC clears after 100 malfunction-free ignition cycles.

### Diagnostic Aids

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.

### Reference Information

#### 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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### 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

1. Ignition OFF, disconnect the antenna coax from the DRR. Connect the EL-48028 to the DRR.
2. Radio ON, tuned to XM™, verify DTC B1259 is not set.

⇒ | If the DTC is set, 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 4.5-5.5 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 digital radio antenna.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Digital Radio Antenna Cable Replacement

• | Digital Radio Antenna Replacement

• | Control Module References for DRR replacement, setup, and programming