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.

### 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

### Diagnostic Aids

Poor AM and FM radio reception is dependent on multiple influences, some of which may not be vehicle related. Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio reception may also be influenced by items within the vehicle, but not part of the radio system. Such examples are aftermarket electrical accessories or other items which may generated noise in the vehicle electrical system.

### 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

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Inspect the antenna for proper mounting or physical damage.

⇒ | If damage is found, repair or replace as necessary

2. Radio ON, tune to several known AM and FM stations, and play a known good CD.

⇒ | If audio output is poor from all sources, refer to Speaker Malfunction.

### Circuit/System Testing

1. Ignition OFF, disconnect the coax cable from the radio and radio antenna.
2. Verify the coax connectors are properly secured and free of any damage.

⇒ | If damage is found, repair or replace as necessary.

3. Test for infinite resistance between the antenna coax center terminal and ground.

⇒ | If less than the specified value, replace the antenna coax.

4. Test for less than 5 ohms on the antenna coax center terminal from end to end.

⇒ | If greater than the specified range, replace the antenna coax.

5. Test for less than 5 ohms on the antenna coax outer shield from end to end.

⇒ | If greater than the specified range, replace the antenna coax.

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

⇒ | If less than the specified value, replace the antenna coax.

7. If all circuits test normal, replace the antenna.
8. Ignition ON, radio ON, verify radio reception has improved.

⇒ | If there is still poor reception, replace the radio.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for Radio replacement, setup, and programming