PRE-RELEASE
Radio Poor Reception
| Radio Poor Reception |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
| Radio Antenna Coax | B125A 02 | B125A 04 | 1 | - |
| Ground | - | 1 | - | - |
| 1. May exhibit possible AM/FM interference. | ||||
| Circuit/System Description |
AM and FM radio reception is dependent on the following components:
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Radio antenna
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Coax cable between the radio antenna and the radio
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Radio
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The multi-band antenna is located on the roof of the vehicle. The radio antenna is enabled when the radio is turned on. The radio provides battery voltage to the antenna using the center conductor of the antenna coaxial cable. When a 12 V signal is seen on the center conductor of the antenna coax, both AM and FM signals are amplified.
| 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 antenna receiving battery voltage from the radio. The antenna has a built in antenna amplifier that boosts both AM and FM reception. If the antenna does not receive battery voltage, the radio will still receive FM stations but AM stations will not be received.
| 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
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Verification |
| 1. |
Inspect the antenna for proper mounting or physical damage.
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| 2. |
If damage is found, repair or replace as necessary
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Radio ON, tune to several known strong FM, AM, and XM (if equipped) stations, and play a known good CD. Verify clear sound from all sources.
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If audio quality is poor from all sources, refer to
Speaker Malfunction
.
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| Circuit/System Testing |
| 1. |
Ignition OFF, disconnect the radio antenna coax from the A11 radio and from the radio antenna.
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| 2. |
Test for infinite resistance between the antenna coax center terminal and ground.
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If less than the specified value, replace the antenna coax.
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Test for less than 5 Ω on the antenna coax center circuit from end to end.
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If greater than the specified range, replace the antenna coax.
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Ignition ON, test for less than 1 V between the antenna coax center terminal and ground.
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If greater than the specified range, replace the antenna coax.
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Test for infinite resistance between the coax center terminal and the outer shield.
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If less than the specified value, replace the antenna coax.
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Connect the antenna coax to the A11 radio. Test for 12-15 V between the antenna coax center terminal and ground at the radio antenna connector.
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If not within the specified range, replace the A11 radio.
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| 12. |
If all circuits test normal, replace the radio antenna.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Radio Antenna Base Replacement
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Control Module References
for radio replacement, setup, and programming
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