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8F - 6
AUDIO SYSTEMS
DIAGNOSIS AND TESTING (Continued)
RADIO FREQUENCY INTERFERENCE
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER
TO
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
For complete circuit diagrams, see Group 8W -
Wiring Diagrams. Inspect the ground paths and con-
nections at the following locations:
• Blower motor
• Electric fuel pump
• Engine-to-body ground strap
• Engine-to-frame ground strap
• Generator
• Ignition module
• Radio antenna base ground
• Radio receiver chassis ground wire or strap
• Wiper motor.
If the source of RFI or EMI noise is identified as a
component on the vehicle (i.e., generator, blower
motor, etc.), the ground path for that component
should be checked. If excessive resistance is found in
any ground circuit, clean, tighten, or repair the
ground circuits or connections to ground as required
before considering any component replacement.
For service and inspection of secondary ignition
components, refer to the Diagnosis and Testing sec-
tion of Group 8D - Ignition Systems. Inspect the fol-
lowing secondary ignition system components:
• Distributor cap and rotor
• Ignition coil
• Spark plugs
• Spark plug wire routing and condition.
Reroute the spark plug wires or replace the faulty
components as required.
If the source of the RFI or EMI noise is identified
as two-way mobile radio or telephone equipment,
check the equipment installation for the following:
• Power connections should be made directly to
the battery, and fused as closely to the battery as
possible.
• The antenna should be mounted on the roof or
toward the rear of the vehicle. Remember that mag-
netic antenna mounts on the roof panel can adversely
affect the operation of an overhead console compass,
if the vehicle is so equipped.
• The antenna cable should be fully shielded coax-
ial cable, should be as short as is practical, and
should be routed away from the factory-installed
vehicle wire harnesses whenever possible.
GROUP
8M
-
PASSIVE
STEERING
COLUMN,
• The antenna and cable must be carefully
matched to ensure a low Standing Wave Ratio
(SWR).
Fleet vehicles are available with an extra-cost RFI-
suppressed Powertrain Control Module (PCM). This
unit reduces interference generated by the PCM on
OR
some radio frequencies used in two-way radio com-
munications. However, this unit will not resolve com-
plaints of RFI in the commercial AM or FM radio
frequency ranges.
REMOVAL AND INSTALLATION
RADIO
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative cable.
(2) Remove the instrument panel top cover from
the instrument panel. Refer to Instrument Panel Top
Cover in Group 8E - Instrument Panel Systems for
the procedures.
(3) Remove the ash receiver from the ash receiver
housing in the lower instrument panel center bezel.
(4) Remove the one screw located in the back of
the ash receiver housing that secures the center
bezel to the lower instrument panel (Fig. 2).
(5) Remove the two screws that secure the center
bezel to the top of the instrument panel.
(6) Using a trim stick or another suitable wide
flat-bladed tool, gently pry the lower edge of the cen-
ter bezel away from the instrument panel.
(7) Lift the lower edge of the center bezel upwards
to release the four snap clip retainers that secure it
to the instrument panel.
(8) Remove the center bezel from the instrument
panel.
(9) Remove the two screws that secure the radio to
the instrument panel (Fig. 3).
(10) Pull the radio out from the instrument panel
far enough to access the wire harness connectors and
the antenna coaxial cable connector (Fig. 4).
(11) Unplug the wire harness connectors and the
antenna coaxial cable connector from the rear of the
radio.
(12) Remove the screw that secures the ground
strap to the radio chassis.
(13) Remove the radio from the instrument panel.
TO
GROUP
8M
-
STEERING
COLUMN,
TJ
PASSIVE
OR
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