RADIO NOISE SUPPRESSION
COMPONENTS
DESCRIPTION
Radio Frequency Interference (RFI) and Electro-
Magnetic Interference (EMI) noise suppression is
accomplished primarily through circuitry internal to
the radio receivers. These internal suppression
devices are only serviced as part of the radio receiver.
External suppression devices that are used on this
vehicle to control RFI or EMI noise include the fol-
lowing:
²Radio antenna base ground
²Radio receiver chassis ground wire or strap
²Engine-to-body ground straps
²Cab-to-bed ground strap
²Heater core ground strap
²Resistor-type spark plugs
²Radio suppression-type secondary ignition wir-
ing.
For more information on the spark plugs and sec-
ondary ignition components, refer to Electrical, Igni-
tion Control.
DIAGNOSIS AND TESTING - RADIO NOISE
SUPPRESSION COMPONENTS
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO ELECTRICAL, RESTRAINTS
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
For complete circuit diagrams, refer to the appro-
priate wiring information. The wiring information
includes wiring diagrams, proper wire and connector
repair procedures, details of wire harness routing
and retention, connector pin-out information and
location views for the various wire harness connec-
tors, splices and grounds. Inspect the ground paths
and connections at the following locations:
²Blower motor
²Cab-to-bed ground strap
²Electric fuel pump
²Engine-to-body ground straps
²Generator
²Ignition module
²Heater core ground strap
²Radio antenna base ground
²Radio receiver chassis ground wire or strap
²Wiper 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 Electrical, Ignition Control.
Inspect the following secondary ignition system com-
ponents:
²Distributor cap and rotor
²Ignition coil
²Spark plugs
²Spark 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:
²Power connections should be made directly to
the battery, and fused as closely to the battery as
possible.
²The 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.
²The 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.
²The 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
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.
ENGINE-TO-BODY GROUND
STRAP
REMOVAL
(1) Remove the screw that secures the engine-to-
body ground strap eyelet to the dash panel (Fig. 10).
(2) Remove the screw that secures the engine-to-
body ground strap eyelet to the back of the engine
cylinder head (Fig. 11) or (Fig. 12).
8A - 12 AUDIOBR/BE
RADIO C1 - GRAY 7 WAY
CAV CIRCUIT FUNCTION
1- -
2 X55 18BR/RD LEFT FRONT DOOR SPEAKER (-)
3 X56 18DB/RD RIGHT FRONT DOOR SPEAKER (-)
4 E17 18YL/BK DAY BRIGHTNESS SENSE
5 E2 22OR PANEL LAMPS FEED
6 X12 16RD/WT FUSED IGNITION SWITCH OUTPUT (RUN-ACC)
7 M1 22PK FUSED B(+)
RADIO C2 - BLACK 7 WAY
CAV CIRCUIT FUNCTION
1 X16 22LG ANTENNA RELAY OUTPUT
2 X51 18BR/YL LEFT REAR SPEAKER (+)
3 X52 18DB/WT RIGHT REAR SPEAKER (+)
4 X53 18DG LEFT FRONT DOOR SPEAKER (+)
5 X54 18VT RIGHT FRONT DOOR SPEAKER (+)
6 X57 18BR/LB LEFT REAR SPEAKER (-)
7 X58 18DB/OR RIGHT REAR SPEAKER (-)
RADIO C3-2WAY
CAV CIRCUIT FUNCTION
1 D1 20VT/BR CCD BUS (+)
2 D2 20WT/BK CCD BUS (-)
RADIO CHOKE RELAY - BLACK 4 WAY
CAV CIRCUIT FUNCTION
1 X60 16DG/RD FUSED IGNITION SWITCH OUTPUT (RUN-ACC)
2 X13 16BK/RD RADIO CHOKE RELAY OUTPUT
3 X16 22LG ANTENNA RELAY OUTPUT
4 Z9 16BK/VT GROUND
REAR WHEEL SPEED SENSOR (ABS)-2WAY
CAV CIRCUIT FUNCTION
1 B114 20WT/VT REAR WHEEL SPEED SENSOR (-)
2 B113 20RD/VT REAR WHEEL SPEED SENSOR (+)
8W - 80 - 74 8W-80 CONNECTOR PIN-OUTSBR/BE
²Glove Box- The hinged bin-type glove box in
the passenger side of the instrument panel features a
recessed paddle-operated latch handle. Three molded
hook formations on the lower edge of the glove box
door are engaged with and pivot on three hinge pins
integral to the lower edge of the instrument panel
support structure. The glove box door also serves as
the passenger side knee blocker. A honeycomb struc-
ture between the inner and outer glove box door pan-
els helps to absorb the impact load and distribute it
to the instrument panel structure.
²Steering Column Opening Cover- The steer-
ing column opening cover serves as the driver side
knee blocker. This molded plastic cover has an inte-
gral ribbed plastic liner concealed behind it, for
increased strength and integrity. The steering column
opening cover transfers impact loads to the instru-
ment panel structural support.
²Top Cover- The instrument panel top cover or
base trim is the molded, grained, and color impreg-
nated plastic outer skin of the instrument panel
structural support.
Hard wired circuitry connects the electrical compo-
nents on the instrument panel to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained by
many different methods. These circuits may be con-
nected to each other, to the vehicle electrical system
and to the instrument panel components through the
use of a combination of soldered splices, splice block
connectors and many different types of wire harness
terminal connectors and insulators. Refer to the
appropriate wiring information. The wiring informa-
tion includes complete circuit diagrams, proper wire
and connector repair procedures, further details on
wire harness routing and retention, as well as pin-
out and location views for the various wire harness
connectors, splices, and grounds.
OPERATION
The instrument panel serves as the command cen-
ter of the vehicle, which necessarily makes it a very
complex unit. The instrument panel is designed to
house the controls and monitors for standard and
optional powertrains, climate control systems, audio
systems, safety systems, and many other comfort or
convenience items. When the components of the
instrument panel structural support are properly
assembled and secured in the vehicle they provide
superior instrument panel stiffness and integrity to
help reduce buzzes, squeaks, and rattles. This type of
construction also provides improved energy absorp-
tion which, in conjunction with the dual airbags and
seat belts, helps to improve occupant protection.The instrument panel is also designed so that all of
the various controls can be safely reached and the
monitors can be easily viewed by the vehicle operator
when driving, while still allowing relative ease of
access to each of these items for service. Modular
instrument panel construction allows all of the
gauges and controls to be serviced from the front of
the panel. In addition, most of the instrument panel
electrical components can be accessed without com-
plete instrument panel removal. However, if neces-
sary, the instrument panel can be removed from the
vehicle as an assembly.
The steering column opening cover with its inte-
gral knee blocker located on the driver side of the
instrument panel works in conjunction with the air-
bag system in a frontal vehicle impact to keep the
driver properly positioned for an airbag deployment.
In addition, removal of this component provides
access to the steering column mounts, the steering
column wiring, the Junction Block (JB) (removal of a
snap-fit fuse access panel on the left end of the
instrument panel allows access to the fuses and cir-
cuit breakers), the Central Timer Module (CTM), the
Infinity speaker filter choke and relay unit, much of
the instrument panel wiring, and the gear selector
indicator cable (automatic transmission).
In a frontal collision, the glove box door on the pas-
senger side of the instrument panel provides the
same function for the front seat passenger as the
knee blocker does for the driver. The glove box door
also incorporates a recessed latch handle. Removal of
the glove box provides access to the passenger airbag,
the glove box lamp and switch, the radio antenna
coaxial cable, the heating and air conditioning vac-
uum harness connector, and additional instrument
panel wiring.
Removal of the instrument panel cluster bezel
allows access to the headlamp switch, instrument
cluster, radio, passenger airbag on-off switch, heated
seat switches (if equipped), and the heating and air
conditioning control. Removal of the instrument clus-
ter allows access to the cluster illumination and indi-
cator bulbs, and more of the instrument panel
wiring. Complete instrument panel removal is
required for service of most components internal to
the heating and air conditioning system housing,
including the heater core and the evaporator.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of all of the components and systems mounted on or
in the instrument panel.
23 - 106 INSTRUMENT PANEL SYSTEMBR/BE
INSTRUMENT PANEL SYSTEM (Continued)
left cowl side inner panel. (Refer to 5 - BRAKES/
PARKING BRAKE/RELEASE - REMOVAL).
(b) Disconnect the instrument panel wire har-
ness connector from the park brake switch on the
park brake mechanism.
(c) Disconnect the three connectors (one from the
body wire harness, and two from the headlamp and
dash wire harness) from the three connector recep-
tacles located closest to the dash panel on the back
of the Junction Block (JB).
(d) Remove the screw from the center of the
headlamp and dash wire harness to instrument
panel wire harness bulkhead connector and discon-
nect the connector.
(e) Disconnect the instrument panel wire har-
ness to door wire harness connector located directly
below the instrument panel wire harness to head-
lamp and dash wire harness bulkhead connector.
(f) If the vehicle is equipped with the Infinity
sound system option, disconnect the Infinity wire
harness connector from the instrument panel wire
harness connector that is secured to the outboard
side of the instrument panel wire harness to head-
lamp and dash wire harness bulkhead connector.(g) Disconnect the instrument panel wire har-
ness connector from the stop lamp switch.
(h) Disconnect the heater-A/C housing vacuum
harness connector from the heater-A/C control vac-
uum harness connector located near the left end of
the heater-A/C housing.
(10) From under the passenger side of the instru-
ment panel, disconnect the two halves of the radio
antenna coaxial cable connector.
(11) Loosen the right and left instrument panel
cowl side roll-down bracket screws about 13 mm
(0.50 inch) (Fig. 11).
(12) Remove the five screws that secure the top of
the instrument panel to the top of the dash panel,
removing the center screw last.
(13) Roll down the instrument panel and install a
temporary hook in the center hole on top of the
instrument panel. Secure the other end of the hook
to the center hole in the top of the dash panel. The
hook should support the instrument panel in its
rolled down position about 46 cm (18 inches) from
the dash panel.
(14) With the instrument panel supported in the
roll-down position, disconnect the instrument panel
Fig. 11 Instrument Panel Assembly Remove/Install
1 - PLASTIC NUT
2 - SCREWS3 - SCREWS
23 - 116 INSTRUMENT PANEL SYSTEMBR/BE
INSTRUMENT PANEL ASSEMBLY (Continued)
wire harness connectors from the heater-A/C housing
wire harness connectors.
(15) With the aid of an assistant, remove the tem-
porary hook and lift the instrument panel assembly
off of the roll-down bracket screws and remove it
from the vehicle.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN,
SEAT BELT TENSIONER, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT
AND ISOLATE THE BATTERY NEGATIVE (GROUND)
CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG
SYSTEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS
THE ONLY SURE WAY TO DISABLE THE AIRBAG SYS-
TEM. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT AND POSSIBLE PERSONAL INJURY.
(1)With the aid of an assistant, load the instrument
panel assembly onto the roll-down bracket screws on
the cowl side inner panels in the vehicle (Fig. 11).
Install a temporary hook in the center hole on top of the
instrument panel. Secure the other end of the hook to
the center hole in the top of the dash panel. The hook
should support the instrument panel in its rolled down
position about 46 cm (18 inches) from the dash panel.
(2) With the instrument panel supported in the
roll-down position, reconnect the instrument panel
wire harness connectors to the heater-A/C housing
wire harness connectors.
(3) Remove the temporary hook from the instru-
ment panel and roll the instrument panel up to its
installed position against the dash panel.
(4) Install and tighten the five screws that secure
the top of the instrument panel to the top of the dash
panel. Tighten the screws to 3.2 N´m (28 in. lbs.).
(5) Tighten the right and left instrument panel
cowl side roll-down bracket screws. Tighten the
screws to 11.9 N´m (105 in. lbs.).
(6) From under the passenger side of the instru-
ment panel, reconnect the two halves of the radio
antenna coaxial cable connector.
(7) From under the driver side of the instrument
panel, perform the following:
(a) Engage the park brake release handle link-
age rod with the park brake mechanism on the left
cowl side inner panel. (Refer to 5 - BRAKES/PARK-
ING BRAKE/RELEASE - INSTALLATION).
(b) Reconnect the instrument panel wire harness
connector to the park brake switch on the park
brake mechanism.(c) Reconnect the three connectors (one from the
body wire harness, and two from the headlamp and
dash wire harness) to the three connector recepta-
cles located closest to the dash panel on the back of
the Junction Block (JB).
(d)
Reconnect the headlamp and dash wire harness
to instrument panel wire harness bulkhead connector
and tighten the screw in the center of the connector.
Tighten the screw to 3.5 N´m (31 in. lbs.).
(e) Reconnect the instrument panel wire harness
to door wire harness connector located directly
below the instrument panel wire harness to head-
lamp and dash wire harness bulkhead connector.
(f) If the vehicle is equipped with the Infinity
sound system option, reconnect the Infinity wire
harness connector to the instrument panel wire
harness connector that is secured to the outboard
side of the instrument panel wire harness to head-
lamp and dash wire harness bulkhead connector.
(g) Reconnect the instrument panel wire harness
connector to the stop lamp switch.
(h) Reconnect the heater-A/C housing vacuum
harness connector to the heater-A/C control vac-
uum harness connector located near the left end of
the heater-A/C housing.
(8) Reinstall the steering column into the vehicle.
Be certain that the steering wheel was locked and
secured from rotation to prevent the loss of clock-
spring centering. (Refer to 19 - STEERING/COL-
UMN - INSTALLATION).
(9) If the vehicle is so equipped, reconnect the
overdrive lockout switch pigtail wire connector to the
instrument panel wire harness connector near the
instrument panel lower reinforcement.
(10) Reconnect the clockspring pigtail wire connec-
tor to the instrument panel wire harness connector
at the instrument panel lower reinforcement.
(11) Position the inside hood latch release handle
to the instrument panel lower reinforcement.
(12) Install and tighten the two screws that secure
the inside hood latch release handle to the instru-
ment panel lower reinforcement. Tighten the screws
to 2.8 N´m (25 in. lbs.).
(13) Reinstall the steering column opening cover
onto the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - INSTALLATION).
(14) Reinstall the trim onto the left and right cowl
side inner panels. (Refer to 23 - BODY/INTERIOR/
COWL TRIM COVER - INSTALLATION).
(15) Reinstall the Airbag Control Module (ACM)
and bracket onto the floor panel transmission tunnel.
(Refer to 8 - ELECTRICAL/RESTRAINTS/AIRBAG
CONTROL MODULE - INSTALLATION).
(16) Reconnect the battery negative cable.
BR/BEINSTRUMENT PANEL SYSTEM 23 - 117
INSTRUMENT PANEL ASSEMBLY (Continued)