Radio Poor Reception

Radio Poor Reception

Diagnostic Instructions

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

AM reception is highly dependent on the powered antenna receiving battery voltage from the radio. The powered antenna has a built in antenna amplifier that boosts both AM and FM reception. When the powered antenna no longer receives power, the radio will still receive FM stations and loose all AM stations.

Reference Information
Schematic Reference

Radio/Navigation System Schematics (Radio/Navigation System Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Radio/Audio System Description and Operation (Radio/Audio System Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Inspect the antenna for damage.

If damage found, replace as necessary.

Radio ON, tune to several known FM, AM, and XM (if equipped) stations, and play a known good CD.

If audio output is poor from all sources, refer to Speaker Malfunction (Speaker Malfunction).
If both AM and FM reception is poor, refer to Antenna Circuit Testing.

Circuit/System Testing

Antenna Circuit Testing
1. Disconnect the harness connector at the antenna.
2. Radio ON, verify a test lamp illuminates between the entertainment remote enable signal circuit terminal 1, and ground.

• If test lamp does not illuminate, test the circuit for short to ground or an open/high resistance. If circuit tests normal, replace the radio.

3. Disconnect the antenna coax from the radio and the radio antenna.
4. Test for infinite resistance between the antenna coax center terminal and ground.

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

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

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

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

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

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

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

8. If all circuits test normal, replace the antenna.
9. 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 (Verification Tests) after completing the diagnostic procedure.

* Antenna Cable Replacement (Antenna Cable Replacement)
* Radio Antenna Replacement (Radio Antenna Replacement)
* Control Module References (Programming and Relearning) for Radio replacement, setup, and programming