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 Descriptors

DTC B1272 02: Antenna FM/AM Signal Circuit Low Voltage
DTC B1272 04: Antenna FM/AM Signal Circuit Open

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Radio Antenna Coax | B1271 02 | B1271 04 | 1 | --
1. Poor radio reception

### Circuit/System Description

AM and FM radio reception is dependent on the following components:

• | Radio antenna

• | Coax cable between the radio antenna and the radio

• | Radio

### Conditions for Running the DTC

Radio ON

### Conditions for Setting the DTC

A short to ground or an open/high resistance is detected on the radio antenna coax.

### Action Taken When the DTC Sets

No action is taken when this DTC sets.

### Conditions for Clearing the DTC

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

• | A history DTC will clear after 100 malfunction free ignition cycles.

### Reference Information

#### Schematic Reference

Radio/Audio 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

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Disconnect the harness connector at the radio antenna.
2. Ignition OFF, test for less than 10 ohms between the terminal 2 outer shield and ground.

⇒ | If greater than the specified range, test the antenna coax shield for an open/high resistance. If the coax test normal, replace the radio.

3. Ignition ON, test the terminal 2 center terminal for 9.5-11.0 volts.

⇒ | If greater than the specified range, test the antenna coax center terminal for a short to voltage. If the coax tests normal, replace the radio.

⇒ | If less than the specified range, test the antenna coax center terminal for a short to ground or an open/high resistance. If the coax tests normal, replace the radio.

4. If all circuits test normal, replace the radio antenna.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Radio Antenna Replacement

• | Antenna Cable Replacement