Corvette 2005-2008

Antenna

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Power Antenna



Diagnosis & Testing
Antenna System Test

NOTE
Important: Always zero out the DMM before taking a resistance measurement in order to ensure an accurate reading.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the antenna lead-in connector from the radio receiver.
  4.  
  5. Measure the resistance from the negative battery cable to the coax outer conductor connector.
    1. The resistance measured should be 0.20 ohms or less.
    2.  

  6.  
  7. Test the following when the resistance is greater than 0.20 ohms.
    1. The coaxial cable interconnects for a poor connection or corrosion.
    2.  
    3. Test for an open or high resistance from the battery negative cable to the body.
    4.  

  8.  
  9. After finding and correcting the condition, operate the system in order to verify the repair.
  10.  

Diversity Antenna System

This diversity antenna system is comprised of 3 antennas, 2 radio antenna modules, a coax, and an FM composite signal from the radio to the left antenna module. In AM and WX mode the system functions as follows: The left antenna module takes the signal from the AM antenna. The left antenna module amplifies this signal and sends it to the radio. In FM mode the system functions as follows: In this mode the radio supplies 5-8 volts over the FM composite signal wire and this switches the modules into FM mode. The left antenna module sends 8 volts to power the right antenna module via coax. The right antenna module takes signal from the FM2 antenna and sends it to the left antenna module where it is mixed with the signal from the FM1 antenna. The left antenna module combines and amplifies both signals and sends the combined signal to the radio. The FM composite signal also provides a feedback signal to the left antenna module, which indicates the quality of the signal. The following information lists the most probable cause of the concern to the least probable cause followed by the appropriate test for that condition. If the test leads to the replacement of a component, always inspect for a poor connection before proceeding with the replacement.


NOTE
Perform the Antenna System Test and test the antenna coax cable prior to performing any of the following tests.

Poor Reception on AM Band Only
  1. Defective left antenna module. Replace the left antenna module.
  2.  
  3. Defective AM antenna. Replace the antenna.
  4.  
  5. The FM composite signal circuit to the radio antenna module is open, shorted to ground, or shorted to B+. Test the FM composite signal circuit for an open or short to ground.
  6.  

Poor Reception on Both AM & FM Bands
  1. The antenna enable circuit is open or shorted to ground. Test for battery voltage on the antenna enable circuit at the left antenna module. If the voltage is not near the specified value, test the antenna enable circuit for an open or short to ground.
  2.  
  3. The radio antenna modules are not grounded properly. The module grounding screws should be clean and tight. The antenna module grounds are either a chassis ground or a ground strap. Measure the resistance from the antenna module base plate to a good ground. Resistance should be 0.20 ohms or less. Find and correct the condition if the resistance is out of specification.
  4.  
  5. The FM composite signal circuit to the radio antenna module is open, shorted to ground, or shorted to B+. Test the FM composite signal circuit for an open or short to ground.
  6.  
  7. Defective left antenna module. Replace the left antenna module.
  8.  
  9. Defective left antenna. Replace the left antenna.
  10.  
  11. Defective coax between the left antenna module and the radio.
  12.  
  13. If no failures were found, replace the radio.
  14.  

Poor Reception on FM Band Only
  1. Defective radio, no 12-volt output at the antenna enable circuit. Replace the radio.
  2.  
  3. Defective left or right antenna module. Replace the antenna module.
  4.  
  5. Defective FM1 or FM2 antenna. Replace the antenna.
  6.  
  7. Defective coax between the left and right antenna modules.
  8.  
  9. The FM composite signal circuit to the radio antenna module is open, shorted to ground, or shorted to B+. Test the FM composite signal circuit at the left antenna module for 5-8 volts. If the voltage is not within or near the specified value, test the FM composite signal circuit for an open or short to ground.
  10.  
  11. The coax between the left and right antenna modules is open or shorted to ground or short to B+. Test for 8 volts from the center conductor of the coax from the left antenna module. If the voltage is not within or near the specified value, test the coax for an open or short to ground or short to B+.
  12.  

Removal & Installation
Convertible With Digital Radio Antenna


Click image to see an enlarged view

Fig. Digital Radio Antenna Replacement (Convertible)

  1. Remove the rear compartment lid trim.
  2.  
  3. Disconnect the electrical connectors.
  4.  
  5. Remove the bolt for the digital radio antenna.
  6.  
  7. Remove the retainer for the digital radio antenna.
  8.  
  9. Remove the digital radio antenna.
  10.  

To install:

  1. Install the digital radio antenna.
  2.  
  3. Install the retainer for the digital radio antenna.
  4.  
  5. Install the bolt for the digital radio antenna.
  6.  
  7. Tighten to 53 inch lbs. (6 Nm).
  8.  
  9. Connect the electrical connectors.
  10.  
  11. Install the rear compartment lid trim.
  12.  

Coupe With Digital Radio Antenna


Click image to see an enlarged view

Fig. Digital Radio Antenna Replacement (Coupe)

  1. Remove rear roof panel screws (19)
  2.  
  3. Remove rear roof panel
  4.  
  5. Use a plastic, flat-bladed tool to prevent paint damage when removing antenna.
  6.  
  7. Disconnect the electrical connections.
  8.  

To install:

  1. Connect the electrical connections.
  2.  
  3. Install the antenna into the rear roof panel.
  4.  
  5. Install rear roof panel
  6.  
  7. Install rear roof panel screws (19)
  8.  

With Digital Radio Antenna

The digital radio antenna assembly, located internal to the outside rearview mirror, cannot be serviced separately. Should the digital radio antenna assembly need to be replaced, the entire rearview mirror assembly will need to be replaced.

 
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