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. Disconnect the harness connector at the radio antenna.
2. Ignition OFF, test for less than 10 Ω between the outer shield at terminal 1 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 center terminal at terminal 1 for 9.5-11.0 V

⇒ | 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.

⇒ | 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.

4. If all circuits test normal, replace the radio antenna.
5. 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.

• | Radio Antenna Replacement

• | Antenna Cable Replacement

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