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AUDIO SYSTEMS
8F - 1
AUDIO SYSTEMS
CONTENTS
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GENERAL INFORMATION ..................
POWER ANTENNA RELAY ................
POWER RADIO ANTENNA ................
SERVICE PROCEDURES ...................
STANDARD RADIO ANTENNA ..............
TEST PROCEDURES ......................
GENERAL INFORMATION
DESCRIPTION
For operation of the factory installed radios refer to
the Owners Manual supplied with the vehicle.
All radios receive IGN feed from the 10 amp #10
RADIO fuse.
All vehicles are equipped with an Ignition-Off Draw
(IOD) fuse which is used when the vehicles are origi-
nally shipped from the factory. This fuse #F1, which
is located in the Power Distribution Center, helps to
prevent battery discharge during storage. For specific
location refer to Group 8W - Wiring Diagrams.
The IOD fuse includes the radio memory circuitry
and should be checked if the memory (time or radio
station programming) is inoperative.
The radio is connected to fuse #8 in order to retain
the radio’s memory when the ignition switch is
turned to OFF.
The electronically tuned (ETR) radio is self
compensating. A radio trimmer adjustment is
not required.
deteriorated spark plug wires should be replaced.
RADIO NOISE DIAGNOSIS
INTERFERENCE ELIMINATION
A number of components are used on vehicles
equipped with a radio, to suppress radio frequency
interference (static).
Capacitors are mounted in the generator and power
mirror motors.
Radio resistance type spark plugs in the high ten-
sion circuit of the ignition system complete the inter-
ference suppression.
If radio noises are evident, isolate circuits with
capacitors to be sure they are the cause. Faulty or
 8F - 2 AUDIO SYSTEMS
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TEST PROCEDURES
RADIO DIAGNOSIS
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AUDIO SYSTEMS 8F - 3
RADIO SCHEMATIC
8F - 4 AUDIO SYSTEMS
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SPEAKER DIAGNOSIS
AM/FM/STEREO—STEREO CASSETTE
(2) Move balance and fader control to Left Front,
Right Front, Right Rear, and Left Rear. If sound is
heard from any speaker during any of these positions
there is a short in one of the speaker feed wires.
(a) If front speakers have normal sound; one rear
speaker has low sound and the other has no sound,
then the speaker with low sound has a short in its
feed line. Check wires to BLACK connector pins 5
and 6 for shorts to vehicle chassis.
(b) If rear speakers have normal sound; one front
speaker has low sound and the other has no sound,
then the speaker with low sound has a short in its
Short Circuits
On some radios, if a speaker wire is shorted the
audio output will automatically shut down. Turn
fader and balance controls to mid position and volume
at mid position. If display operates and there is no
volume from any speaker proceed to the Short test.
Short Circuit Test
(1) Turn radio on to mid volume.
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AUDIO SYSTEMS
8F - 5
feed line. Check wires to BLACK connector pins 3
and 4 for shorts to vehicle chassis.
(3) If no sound is heard while adjusting the balance
and fader controls there still may be a short in one of
the 4 speaker return lines. Check speaker wires con-
nected to GRAY connector pins 5 and 6 for shorts to
vehicle chassis.
(4) If all the tests show no problem, replace radio.
ANTENNA TESTING
ANTENNA DIAGNOSIS
Fig. 1 Antenna Test Points
Antenna performance may be tested by substituting
a known good antenna. Check short or open circuits
with an ohmmeter or continuity light once the an-
tenna cable is disconnected from the radio as follows:
(1) Continuity should be observed between the tip
of the mast and radio end pin (Fig. 1).
(2) No continuity or a very high resistance of sev-
eral megohms should be observed between the ground
shell of the connector and radio end pin.
(3) Continuity should be observed between the
ground shell of the connector and the mounting hard-
ware on the fender.
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