Radio Poor Reception
Diagnostic Instructions
Circuit/System Description
AM and FM radio reception is dependent on the following components:
• | Coax cable between the radio aerial and the radio aerial module |
• | Coax cable between the radio aerial module and the 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. Aftermarket window tinting, especially when there is a metallic in the film, may reduce radio reception.
For the Diversity aerial system, reception is highly dependent on the aerial module receiving battery voltage from the radio. The aerial module has a built in aerial amplifier that boosts both AM and FM reception. The aerial module will switch between the internal and external aerial for best reception and provide feedback of this signal through the coax cable that connects the radio to the aerial module.
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
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
Aerial Circuit Testing w/o US3
- Ignition OFF, disconnect the radio aerial coax cable from the radio and the radio aerial.
- Test for infinite resistance between the aerial coax centre terminal and ground.
⇒ | If less than the specified value, replace the aerial coax. |
- Test for less than 10 Ω on the aerial coax centre terminal from end to end.
⇒ | If greater than the specified range, replace the aerial coax. |
- Test for less than 10 Ω on the aerial coax outer shield from end to end.
⇒ | If greater than the specified range, replace the aerial coax. |
- Test for infinite resistance between the coax centre terminal and the outer shield.
⇒ | If less than the specified value, replace the aerial coax. |
- Reconnect the coax to the radio aerial. Test for infinite resistance on the coax at the radio between the centre terminal and the outer shield.
⇒ | If less then specified value, replace the aerial. |
- Test for less than 10 Ω on the coax at the radio between the outer shield and ground.
⇒ | If greater than specified value, clean the mounting surface of the aerial ground plane. If no corrosion found, replace the aerial. |
- If all circuits test normal, replace the radio.
Aerial Circuit Testing w/US3
- Ignition OFF, disconnect the radio aerial coax from the aerial module.
- Ignition ON, radio tuned to FM, test for greater than 10 V between the coaxial centre terminal and ground.
⇒ | If less than specified range, test the coax cable for a short to ground, or an open high resistance. If the cable test normal, replace the radio. |
- Radio tuned to AM, test for less than 1 V between the coaxial centre terminal and ground.
⇒ | If greater than the specified range, test the coax for a short to voltage. If the cable test normal, replace the radio. |
- Inspect the radio aerial module grounding surfaces and the mounting hardware for any corrosion that may cause a poor ground.
⇒ | If corrosion is noted, clean the grounding surfaces or hardware. |
- Disconnect the X1 harness connector at the aerial module.
- Ignition ON, 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. |
- If all circuits test normal, replace the aerial module.
- 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.
© Copyright Chevrolet. All rights reserved |