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 antennas - left and right - part of the rear decklid
* Coax cables between the radio antennas and the radio antenna modules
* Radio antenna modules - right and left
* Coax cables between the radio antenna modules 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.
Diagnosing a poor reception concern will require a systematic approach to isolating the cause. Individual components should each be tested before proceeding with any repair or replacement.
Using a Test Antenna
Use a test mast antenna to check for poor vehicle antenna operation. Disconnect the antenna coax from the radio and plug the test antenna into radio. Make sure the test antenna base is grounded to the vehicle chassis and keep hands off the mast. Check radio reception in an area away from electrical interferences. Tune to several weak and strong AM and FM stations. If the radio reception improved, the problem exists with the vehicle antenna and/or lead-in cable. If the reception is still poor, refer to Speaker Malfunction (Speaker Malfunction) .
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 Testing
Antenna Coaxial Cable Testing
Important: For steps 2-5, perform the tests on each of the disconnected coax cables.
1. Ignition OFF, disconnect all coax cables from the radio, radio antenna modules, and both antennas in the rear decklid.
2. Test for infinite resistance between the antenna coax center terminal and ground.
• If less than the specified value, replace the antenna coax.
3. 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.
4. 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.
5. Test for infinite resistance between the coax center terminal and the outer shield.
• If less than the specified value, replace the antenna coax.
Antenna Inspection
1. Ignition OFF, disconnect the coax cables from the right and left antennas located at the rear decklid.
2. Verify the coax connectors are properly secured and free of any damage.
• If damage is found, repair or replace as necessary.
3. Inspect each antenna. Verify all branches of the antennas are intact, with no scratches or other damage.
• If damage is found, repair or replace as necessary.
Radio Antenna Module Test
1. Inspect each radio antenna module grounding surface and the mounting hardware for any corrosion that may cause a poor ground.
• If corrosion is noted, clean the grounding surfaces and hardware.
2. Ignition OFF, disconnect the harness connector at the right radio antenna module.
3. Radio ON, test for B+ between the signal circuit terminal 1 and ground.
• If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
4. Ignition OFF, disconnect the X1 harness connector at the radio.
5. Verify that a test lamp does not illuminate between B+ and the FM corporate signal circuit terminal E4.
• If the test lamp illuminates, test the signal circuit for a short to ground.
6. Test for less than 5 ohms between the FM corporate signal circuit terminal E4 at the X1 radio harness connector and terminal 2 at the right radio antenna module harness connector.
• If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance.
7. Ignition ON, with the scan tool observe and record the radio signal strength db parameter.
8. Disconnect the left antenna from the left radio antenna module and verify a drop in db signal strength.
• If the signal strength did not significantly drop, replace the left antenna.
9. Connect the harness connector at the left antenna.
10. Disconnect the right antenna from the right radio antenna module and verify a drop in db signal strength.
• If the signal strength did not significantly drop, replace the right antenna.
11. If all circuits test normal, replace the radio antenna module assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Radio Antenna Module Replacement (Radio Antenna Module Replacement)
* Antenna Ground Plate Replacement (Service and Repair)
* Antenna Cable Replacement (Antenna Cable Replacement)
* Fixed Antenna Replacement (Fixed Antenna Replacement)
* Control Module References (Programming and Relearning) for Radio replacement, setup, and programming