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Radio Poor Reception

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Radio Aerial 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:

    • Radio aerial
    • Coax cable between the radio antenna and the radio
    • Radio

The multi-band antenna is located on the roof of the vehicle. The radio aerial is enabled when the radio is turned on. The radio provides battery voltage to the aerial using the centre conductor of the aerial coaxial cable. When a 12 V signal is seen on the centre conductor of the aerial 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 aerial receiving battery voltage from the radio. The aerial has a built in aerial amplifier that boosts both AM and FM reception. If the aerial 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

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Inspect the aerial for proper mounting or physical damage.
  2. If damage is found, repair or replace as necessary
  3. 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.
  4. If audio quality is poor from all sources, refer to Speaker Malfunction .

Circuit/System Testing

  1. Ignition OFF, disconnect the radio aerial coax from the A11 radio and from the radio aerial.
  2. Test for infinite resistance between the aerial coax centre terminal and ground.
  3. If less than the specified value, replace the aerial coax.
  4. Test for less than 5 Ω on the aerial coax centre circuit from end to end.
  5. If greater than the specified range, replace the aerial coax.
  6. Ignition ON, test for less than 1 V between the aerial coax centre terminal and ground.
  7. If greater than the specified range, replace the aerial coax.
  8. Test for infinite resistance between the coax centre terminal and the outer shield.
  9. If less than the specified value, replace the aerial coax.
  10. Connect the aerial coax to the A11 radio. Test for 12-15 V between the aerial coax centre terminal and ground at the radio aerial connector.
  11. If not within the specified range, replace the A11 radio.
  12. If all circuits test normal, replace the radio aerial.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Radio Aerial Base Replacement
    • Control Module References for radio replacement, setup, and programming.
   


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