Radio Poor Reception
Radio Poor Reception
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Active Antenna
The active antenna system uses an integral antenna applied as an appliqué to the rear glass. The antenna module receives both AM and FM signals from the rear glass antenna. The radio antenna module is enabled when the radio is turned on. The radio provides battery voltage to the antenna module using the center conductor of the antenna coaxial cable. When a 12 V signal is seen by the module on the center conductor of the antenna coax, both AM and FM signals are amplified.
Diversity Antenna
The diversity antenna system uses two integral antennas applied as appliqués to the rear glass. Any damage to the antenna requires replacing the glass. Each antenna is part of the window and looks similar to the defogger grid. The right antenna receives both AM and FM signals. The left antenna receives only FM signals.
The antenna reception signals are sorted out by the radio antenna modules. The right radio antenna module is enabled when the radio is turned on. The radio provides battery voltage to the antenna module using the remote enable circuit. When the AM band is selected on the radio, the right antenna module connects the right antenna directly to the radio.
When the FM band is selected an enable signal is sent to the left antenna module from the right antenna module via the antenna coax. The left antenna module receives the FM signal from the left antenna and passes this signal to the right antenna module. The right antenna module switches between the left and right antennas, combining both signals and aligning them to create one strong signal.
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 generate noise in the vehicle electrical system. Aftermarket window tinting, especially when there is a metallic in the film, may reduce radio reception.
AM reception is highly dependent on the antenna module receiving battery voltage from the radio and being properly grounded. The antenna module has a built in antenna amplifier that boosts both AM and FM reception. When the antenna module does not receive power, AM stations may not be received and FM reception will be limited. If the module is not properly grounded, excessive interference in the signal may occur, or reception may be limited.
Reference Information
Schematic Reference
Radio/Navigation System Schematics Radio/Navigation System Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Radio/Audio System Description and Operation (with Color Display) Radio/Audio System Description and Operation (with Color Display)Radio/Audio System Description and Operation (with Monochrome Display) Radio/Audio System Description and Operation (with Monochrome Display)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Inspect the antenna(s) located in the rear window. Verify all branches of the antennas are intact, with no scratches or other damage.
• If damage is found, repair or replace as necessary
2. Radio ON, tune to several known FM and AM stations, and play a known good CD.
• If audio output is poor from all sources, refer to Speaker Malfunction Speaker Malfunction.
3. If poor reception is noted in AM or FM band, refer to Circuit/System testing.
Circuit/System Testing
Active Antenna (U77)
1. Inspect the 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 radio antenna coax from the A11 radio and from the K46 radio antenna module.
3. Perform the coax cable component test on the radio antenna coax. Refer to component testing. Verify the radio antenna coax cable passes the test.
• If the radio antenna coax cable does not pass the test, replace the antenna coax.
4. Reconnect the antenna coax cable at the A11 radio.
5. Ignition ON, radio ON. Test for 12-15 V between the antenna coax center terminal and ground at the radio antenna module connector.
• If not within the specified range, replace the A11 radio.
6. If all circuits test normal, replace the K46 radio antenna module. Reconnect all connections. Radio ON, verify the radio reception has improved.
• If there is still poor reception, replace the radio.
Diversity Antenna (US3)
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 X3 harness connector at the K46R radio antenna module- right.
3. Ignition ON, radio ON. Verify a test lamp illuminates between the remote enable circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the A11 radio.
4. Ignition OFF, disconnect the coax cable between the K46R radio antenna module- right and the K46L radio antenna module- left.
5. Perform the coax cable component test on the antenna coax. Refer to component testing. Verify the antenna coax cable passes the test.
• If the coax cable does not pass the test, replace the antenna coax.
6. Disconnect the radio antenna coax from the A11 radio and from the K46R radio antenna module- right.
7. Perform the coax cable component test on the radio antenna coax. Refer to component testing. Verify the radio antenna coax cable passes the test.
• If the radio antenna coax cable does not pass the test, replace the antenna coax.
8. If all circuits test normal, replace the K46L radio antenna module- left. Reconnect all connections. Radio ON, verify the radio reception has improved.
• If there is still poor reception, replace the K46R radio antenna module- right. If there is still poor reception, replace the radio.
Component Testing
Caution:
Refer to Test Probe Caution Test Probe Caution.
Note:
Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.
To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.
Coax Cable Test
1. Vehicle OFF, disconnect the coax cable at both components.
2. Test for less than 5 ohms between both ends of the coax cables center terminals.
• If greater than the specified range, replace the coax cable
3. Test for less than 5 ohms between both ends of the coax cable outer shield.
• If greater than the specified range, replace the coax cable
4. Test for infinite resistance between the coax cable center wire and the outer coax shield.
• If less than the specified range, replace the coax cable.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Radio Antenna Module Replacement Radio Antenna Module Replacement
* Control Module References Control Module References for radio replacement, setup, and programming