Schematic Reference:
Radio/Audio System Schematics
Diagnostic System Check - Entertainment
Always perform the Diagnostic System Check - Entertainment, before proceeding
with these diagnostic procedures. Refer to
Diagnostic System Check - Entertainment System
.
Diversity Antenna System
This diversity antenna system is comprised of 3 antenna grid patterns, two radio
antenna modules, a coax, and a FM composite signal from the radio to the passenger
antenna module. In AM and WX mode the system functions as follows:
The passenger antenna module takes the signal from only the AM/FM1 antenna pattern
on the right side quarter glass window. The passenger antenna module amplifies this
signal and sends it to the radio. In this mode the driver antenna module sends 8 V
to power the passenger antenna module via coax.
In FM mode the system functions as follows:
The driver antenna module takes signal from FM antenna pattern on the left side
quarter glass window and sends it to the passenger antenna module where it is mixed
with the signal from the right side rear quarter glass window. The driver antenna
module combines and amplifies both signals and sends it to the radio. In this mode
the radio supplies 5-8 Volts over the FM composite signal wire and this
switches the modules into FM mode. The driver antenna module sends 8 Volts to power
the passenger antenna module via coax. The FM composite signal also provides a feedback
signal to the passenger 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. Refer to
Testing for Intermittent Conditions and Poor Connections
and
Connector Repairs
in Wiring Systems.
Test the antenna coax cable prior to performing any of the following tests.
Important: If the driver antenna module is replaced you must perform the transmitter programming
procedure for the radio antenna module. Refer to
Transmitter Programming
in Keyless Entry. If the vehicle is equipped with Tire Pressure
Monitoring (UJ6) then perform the Tire Pressure Learn procedure. Refer to
Tire Pressure Sensor Learn
in Tire Pressure Monitoring.
Poor Reception on Both AM and FM Bands
| • | The radio antenna modules are not grounded properly. The module grounding
screws should be clean and tight. The antenna module grounds are a chassis ground.
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. |
| • | The coax between the driver and passenger antenna modules is open or
shorted to ground or short to B+. Test for 8 V from the center conductor
of the coax from the passenger antenna module. If the voltage is not near the specified
value, test the coax for an open or short for ground or short to B+. Refer to
Circuit Testing
and
Wiring Repairs
in Wiring Systems. |
| • | 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. Refer to
Circuit Testing
and
Wiring Repairs
in Wiring Systems. |
Poor Reception on AM Band Only
| • | Defective coax between the driver and passenger antenna modules. Test
for 8 Volts on the center conductor. Refer to
Circuit Testing
and
Wiring Repairs
in Wiring Systems. |
Poor Reception on FM Band Only
| • | FM composite signal circuit shorted to B+. Test the circuit for a short
to voltage. Refer to
Circuit Testing
and
Wiring Repairs
in Wiring Systems. |
