Radio Replacement; Wheel And Tire Static; Turn And Stop Signals; Horn Noise - Jeep 1979 CJ-5 Technical & Service Manual

RADIO SOUND SYSTEMS 3V-9
Defective Radio
Exchange with a known good radio to determine if the
radio is defective.
Direct Entry into the Radio
(1) Be sure radio has a good ground.
(2) Tighten all radio chassis screws.
Wheel and Tire Static
Wheel static is another source of interference. This is
a running noise most likely to be encountered when the
vehicle is in motion on a hard, dry-surfaced road. The
noise will remain when the vehicle is coasting with the
engine and all electrical equipment turned off. The
static occurs in the front wheels due to insulating film
produced by the lubricant in the wheel bearings.
In some instances, static discharges take place be-
tween the tire and the road surface. An anti-static pow-
der kit is available from radio supply houses which
applies conducting material to the inside surface of the
tire to eliminate noise from this source. Tire static can
be checked by washing the tire with water. The water
provides a conduction path to ground for the discharges.
Tire static is most likely to be encountered during hot,
dry seasons.
Turn and Stop Signals
The flasher in the turn signals and the switch in the
stop signal may cause popping noises in the radio. In
most cases, the noises are interference due to arcing in
the contacts. The correction is a 0.5-mfd bypass capaci-
tor installed at the battery connection of the switch or
the flasher. It is less likely, but possible, t h a t the low
frequency components of the interruptions are reaching
audio stages of the radio. The test is to check if the noise
is present with the volume control turned down. If so,
install a 1,000-mfd condenser.
Horn Noise
The diagnosis and cure for a growling noise in the
radio when the horn is operated is the same as for Turn
and Stop Signals detailed above. The suppressor capaci-
tors are installed at the point where the battery lead
feeds the horn relay.
Be sure the horn relay cover is not loose.
Accessories
Electric windshield wipers, blower motors, window
regulator motors, or any brush-type motors, generally
can be suppressed by installing 0.25-mfd capacitors at
the terminals.
CB RADIO DIAGNOSIS
For possible CB radio problems, refer to CB Radio
Reception to determine if the condition is normal. If
problem still exists, use CB Radio test instruments (fig.
3V-15) to diagnose trouble.
80669
Fig. 3V-15 Amserv AMX 386S Mobile CB Tester
RADIO REPLACEMENT
CJModils
NOTE:
If equipped with air conditioning, remove
screws attaching evaporator assembly to instrument
panel and lower evaporator assembly.
(1) Disconnect battery negative cable.
(2) Remove radio control knobs, attaching nuts, and
bezel.
(3) Disconnect radio support bracket from in-
strument panel.
(4) Remove radio by tilting it downward and to-
ward steering wheel.
(5) Disconnect antenna lead, speaker wires, and
feed wire.
(6) Remove bracket from radio and install on re-
placement radio.
(7) Connect antenna lead, speaker wires, and feed
wire to replacement radio.