roof DODGE RAM 2002 Service Repair Manual

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

(9) Disconnect the instrument panel wire harness
connector for the multi-function switch from the
switch connector receptacle. Check for continuity
between the hazard flasher signal circuit cavities in
the JB receptacle for the combination flasher and the
instrument panel wire harness connector for the
multi-function switch. There should be continuity. If
OK, go to Step 10. If not OK, repair the open hazard
flasher signal circuit between the JB and the multi-
function switch as required.
(10) Check for continuity between the flasher out-
put circuit cavities of the JB receptacle for the com-
bination flasher and in the instrument panel wire
harness connector for the multi-function switch.
There should be continuity. If OK, test the multi-
function switch. (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - EXTERIOR/MULTI-FUNCTION
SWITCH - DIAGNOSIS AND TESTING). If not OK,
repair the open flasher output circuit between the JB
and the multi-function switch as required.
SPECIFICATIONS
EXTERIOR LAMPS
LAMP BULB
Back-up 3157
Cargo 921
Center High Mounted
Stop921
Clearance Roof Mounted 168
Fog Lamps 896
Headlamp - SLT 9004LL
Headlamp - Sport Low
Beam9007
Headlamp - Sport High
Beam9004LL
License Plate w/o
Bumper1155
License Plate -Step
Bumper168
Park/Turn Signal 3157NA
Snow Plow Control 161
Tail/Brake/Turn Signal 3157
Tail/Brake/Cab - Chassis 1157
Underhood 105
SPECIAL TOOLS
HEADLAMP ALIGNMENT
BRAKE LAMP SWITCH
DESCRIPTION
The plunger type brake lamp switch is mounted on
a bracket attached to the brake pedal support under
the instrument panel.
CAUTION: The switch can only be adjusted during
initial installation. If the switch is not adjusted prop-
erly a new switch must be installed.
OPERATION
The brake lamp switch is used for the brake lamp,
speed control brake sensor circuits and electronic
brake distribution (EBD). The brake lamp circuit is
open until the plunger is depressed. The speed con-
trol and brake sensor circuits are closed until the
plunger is depressed.
When the brake light switch is activated, the Pow-
ertrain Control Module (PCM) receives an input indi-
cating that the brakes are being applied. After
receiving this input, the PCM maintains idle speed to
a scheduled rpm through control of the Idle Air Con-
trol (IAC) motor. The brake switch input is also used
to disable vent and vacuum solenoid output signals
to the speed control servo.
Vehicles equipped with the speed control option use
a dual function brake lamp switch. The PCM moni-
tors the state of the dual function brake lamp switch.
Refer to the Brake section for more information on
brake lamp switch service and adjustment proce-
dures.
Headlamp Aiming Kit C-4466±A
8L - 4 LAMPS/LIGHTING - EXTERIORBR/BE
LAMPS/LIGHTING - EXTERIOR (Continued)

INSTALLATION
(1) Connect harness wires tonewswitch.
(2) Press and hold brake pedal down.
(3) Align tabs on switch with notches in switch
bracket, install the switch and rotate it in bracket
clockwise approximately 30É to lock it in place. (Fig.
3). Make sure the switch lever is in the 45É position
as illistrated in figure 2.
(4) Release brake pedal. With out moving the
pedal, move the lever so that it is parallel with the
connector. The switch is now adjusted and can not be
adjusted again.
(5) Install the knee bolster.
CENTER HIGH MOUNTED
STOP LAMP
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the CHMSL from the roof panel.
(3) Rotate sockets 1/4 turn clockwise and remove
from lamp. (The two center bulbs light the stoplamp
and the outside bulbs light the cargo lamp, if
equipped.)
(4) Pull bulb from socket.
INSTALLATION
(1) Push bulb into socket.
(2) Position socket in lamp an rotate socket 1/4
turn counterclockwise.
(3) Install the CHMSL.
(4) Connect the battery negative cable.
CENTER HIGH MOUNTED
STOP LAMP UNIT
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove screws holding CHMSL to roof panel
(Fig. 4).
(3) Separate CHMSL from roof.
(4) Disengage wire connector from body wire har-
ness.
(5) Separate CHMSL from vehicle.
INSTALLATION
(1) Position lamp at cab roof and connect wire con-
nector.
(2) Install screws holding CHMSL to roof panel.
Tighten securely.
(3) Connect the battery negative cable.
Fig. 3 Brake Lamp Switch
1 - TAB NOTCH (IN BRACKET)
2 - SWITCH PLUNGER
3 - SWITCH TAB
Fig. 4 Center High Mounted Stop Lamp
1 - CHMSL CARGO LAMP HOUSING
2 - CHMSL
3 - CARGO LAMPS
4 - SCREW
5 - CLIP
6 - CAB
8L - 6 LAMPS/LIGHTING - EXTERIORBR/BE
BRAKE LAMP SWITCH (Continued)

CLEARANCE LAMP
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove screws holding clearance lamp lens to
roof panel (Fig. 5).
(3) Rotate socket 1/4 turn counterclockwise and
separate socket from lamp.
INSTALLATION
(1) Install socket in lamp and rotate socket 1/4
turn clockwise.
(2) Position clearance lamp on roof.
(3) Install screws holding clearance lamp lens to
roof panel. Tighten to 1 N´m (13 in. lbs.).
(4) Connect the battery negative cable.
COMBINATION FLASHER
DESCRIPTION
The combination flasher is located in the Junction
Block (JB) behind the fuse access panel on the left
outboard end of the instrument panel. The combina-
tion flasher is a smart relay that functions as both
the turn signal system and the hazard warning sys-
tem flasher. The combination flasher contains active
electronic Integrated Circuitry (IC) elements. This
flasher is designed to handle the current flow
requirements of the factory-installed lighting. If sup-
plemental lighting is added to the turn signal lamp
circuits, such as when towing a trailer with lights,
the combination flasher will automatically try to
compensate to keep the flash rate the same.
The combination flasher has five blade-type termi-
nals that connect it to the vehicle electrical system
through five matching cavities in the receptacle of
the JB. While the combination flasher has a Interna-
tional Standards Organization (ISO)-type relay ter-
minal configuration or footprint, the internal
circuitry is much different. The combination flasher
does not use standard ISO-relay inputs or provide
ISO-relay type outputs or functions. The combination
flasher should never be substituted for an ISO-relay
or replaced with an ISO-relay, or else component and
vehicle damage may occur.
The combination flasher cannot be repaired or
adjusted and, if faulty or damaged, it must be
replaced.
OPERATION
The combination flasher has five blade-type termi-
nals intended for the following inputs and outputs:
fused B(+), fused ignition switch output, ground, turn
signal circuit, and hazard warning circuit. Constant
battery voltage and ground are supplied to the
flasher so that it can perform the hazard warning
function, and ignition switched battery voltage is
supplied for the turn signal function.
Fig. 5 Roof Clearance Lamps
1 - ROOF
2 - LAMP LENS
3 - BULB
4 - SOCKET
5 - PLASTIC NUTS
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 7

(3) If the multi-function switch fails any of the
continuity or resistance tests, replace the faulty
switch unit as required.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. 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) If the vehicle is so equipped, unscrew the lever
from the tilt steering column adjuster mechanism
located on the left side of the column just below the
multi-function switch control stalk. Turn the lever
counterclockwise to unscrew it from the adjuster.
(3) From below the steering column, remove the
two outboard screws that secure the upper shroud to
the lower outer shroud (Fig. 26).
(4) Press carefully inward on each side of the outer
shrouds to release the snap features and remove the
upper outer shroud from the lower outer shroud.
(5) From below the steering column, remove the
one center screw that secures the lower outer shroud
to the steering column housing.
(6) Remove the lower outer shroud from the steer-
ing column.
(7) From below the steering column, remove the
two screws that secure the lower inner shroud to the
steering column housing and the upper inner shroud.
(8) Press carefully inward on the gearshift lever
side of the inner shrouds to release the snap features
and remove the lower inner shroud from the steering
column.
(9) Carefully lift the upper inner shroud upward
far enough to access the multi-function switch
mounting screws.(10) Remove the two tamper proof screws (a Snap
On tamper proof Torx bit TTXR20B2 or equivalent is
required) that secure the multi-function switch to the
steering column housing.
(11) Gently pull the multi-function switch away
from the steering column far enough to access and
remove the screw that secures the instrument panel
wire harness connector for the multi-function switch
to the switch connector receptacle (Fig. 27).
(12) Disconnect the instrument panel wire harness
connector from the multi-function switch connector
receptacle.
(13) Remove the multi-function switch from the
steering column.
Fig. 26 Steering Column Shrouds Remove/Install -
Typical
1 - STEERING WHEEL
2 - TILT LEVER
3 - UPPER SHROUD
4 - PANEL BRACKET
5 - SPACER
6 - TOE PLATE
7 - NUT
8 - LOWER SHROUD
9 - CLOCK SPRING
10 - NUT
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 27
MULTI-FUNCTION SWITCH (Continued)

INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Position the multi-function switch next to the
steering column.
(2) Reconnect the instrument panel wire harness
connector for the multi-function switch to the switch
connector receptacle (Fig. 27).
(3) Install and tighten the screw that secures the
instrument panel wire harness connector for the
multi-function switch to the switch connector recep-
tacle. Tighten the screw to 2 N´m (18 in. lbs.).
(4) Position the multi-function switch onto the
steering column.(5) Carefully lift the upper inner shroud upward
far enough to access the multi-function switch
mounting screws.
(6) Install and tighten the two tamper proof
screws (a Snap On tamper proof Torx bit TTXR20B2
or equivalent is required) that secure the multi-func-
tion switch to the steering column housing. Tighten
the screws to 2 N´m (18 in. lbs.).
(7) Position the lower inner shroud onto the steer-
ing column (Fig. 26). Be certain to insert the gear-
shift lever hider strip into the channel located on the
inside surface of the shroud.
(8) Align the locking tabs on the gearshift lever
side of the upper inner shroud with the receptacles
on the lower inner shroud and apply hand pressure
to snap them together.
(9) From below the steering column, install and
tighten the two screws that secure the lower inner
shroud to the steering column housing and the upper
inner shroud. Tighten the screws to 2 N´m (18 in.
lbs.).
(10) Position the lower outer shroud onto the
steering column.
(11) From below the steering column, install and
tighten the one center screw that secures the lower
outer shroud to the steering column housing. Tighten
the screw to 2 N´m (18 in. lbs.).
(12) Align the locking tabs on the upper outer
shroud with the receptacles on the lower outer
shroud and apply hand pressure to snap them
together.
(13) From below the steering column, install and
tighten the two outboard screws that secure the
lower outer shroud to the upper outer shroud.
Tighten the screws to 2 N´m (18 in. lbs.).
(14) If the vehicle is so equipped, reinstall the
lever into the tilt steering column adjuster on the left
side of the column. Turn the lever clockwise to screw
it into the adjuster.
(15) Reconnect the battery negative cable.
OUTBOARD IDENTIFICATION
LAMP
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Using a flat blade screw driver, carefully pry
lamp to disengage clips attaching ID lamp to retainer
(Fig. 28).
(3) Separate ID lamp from retainer.
(4) Disengage lamp bulb socket from lamp.
(5) Remove screws attaching lamp retainer to rear
fender.
(6) Separate retainer from rear fender.
Fig. 27 Multi-Function Switch Connector
1 - WIRE HARNESS CONNECTORS
2 - SCREW
3 - WIRE HARNESS CONNECTOR
4 - MULTI-FUNCTION SWITCH
5 - WIRE HARNESS CONNECTOR
6 - CLOCKSPRING
7 - IGNITION SWITCH
8L - 28 LAMPS/LIGHTING - EXTERIORBR/BE
MULTI-FUNCTION SWITCH (Continued)

MESSAGE SYSTEMS
TABLE OF CONTENTS
page page
OVERHEAD CONSOLE
DESCRIPTION..........................1
STANDARD PROCEDURE
STANDARD PROCEDURE - COMPASS
CALIBRATION.........................4
STANDARD PROCEDURE - COMPASS
VARIATION ADJUSTMENT................4
STANDARD PROCEDURE - COMPASS
DEMAGNETIZING......................5
REMOVAL
OVERHEAD CONSOLE REMOVAL.........6
DISASSEMBLY
OVERHEAD CONSOLE DISASSEMBLY......7
ASSEMBLY
OVERHEAD CONSOLE ASSEMBLY........8
INSTALLATION
OVERHEAD CONSOLE INSTALLATION......8SPECIAL TOOLS
OVERHEAD CONSOLE SPECIAL TOOL.....9
COMPASS/MINI-TRIP COMPUTER
DESCRIPTION..........................9
OPERATION............................9
DIAGNOSIS AND TESTING - COMPASS
MINI-TRIP COMPUTER.................10
REMOVAL.............................11
INSTALLATION.........................11
AMBIENT TEMP SENSOR
DESCRIPTION.........................12
OPERATION...........................12
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR...............12
REMOVAL.............................12
INSTALLATION.........................13
OVERHEAD CONSOLE
DESCRIPTION
Three different overhead console units are avail-
able factory-installed options on this model, base,
premium and premium with vehicle theft security.
The base overhead console unit features a garage
door opener storage bin, a sunglasses storage bin and
two reading and courtesy lamps. The premium over-
head console has all of the features of the base unit,
but adds a compass mini-trip computer and/or vehi-
cle theft security LED. See the owner's manual in
the vehicle glove box for more information on the fea-
tures, use and operation of all of the overhead con-
sole components and systems. Refer toOverhead
Consolein the Contents of Wiring Diagrams for
complete circuit diagrams.
The premium overhead console (Fig. 1) includes
two front-mounted reading and courtesy lamps, a
garage door opener storage bin, and a sunglasses
storage bin. The premium overhead console includesa compass mini-trip computer. The base overhead
console uses the same overhead console housing, but
has a computer cover plug installed in place of the
compass mini-trip computer display module lens and
push buttons.
The rear of the overhead console is secured to two
rear mounting holes in the inner roof panel by two
plastic hook formations that are integral to the over-
head console housing. The front of the overhead con-
sole is secured to the two front mounting holes of the
inner roof panel by two plastic latches that are inte-
gral to the overhead console housing. A single electri-
cal connection joins the overhead console wire
harness to the roof wire harness for both the base
and premium overhead console units.
Following are general descriptions of the major
components used in the overhead console. See the
owner's manual in the vehicle glove box for more
information on the use and operation of the various
overhead console features.
BR/BEMESSAGE SYSTEMS 8M - 1

GARAGE DOOR OPENER STORAGE BIN
A compartment near the front of the overhead con-
sole is designed to hold most garage door opener
remote control transmitters. The transmitter is
mounted within the compartment with an adhesive-
backed hook and loop fastener patch and, when the
compartment is closed, a push button in the center of
the compartment door is depressed to actuate the
transmitter.
A transmitter mounting kit including the adhesive-
backed hook and loop fastener material is available
for service. The garage door opener storage bin door
and the push button with three assorted length
adapter pegs are also available for service replace-
ment.
The garage door opener storage compartment door
is opened by pressing the integral latch towards the
front of the vehicle. When the compartment door is
opened, the push button unit is removed from the
compartment by squeezing the latch tabs and pulling
the unit downward. With the push button removed,
the garage door opener can be installed in the com-
partment using the adhesive-backed hook and loop
fastener material provided.
With the transmitter mounted in the storage bin,
adapter pegs located on the garage door opener push
button unit are selected and mounted on one of two
posts on the back side of the push button. The com-
bination of the adapter peg length and the push but-
ton post location must be suitable to depress the
button of the transmitter when the push button in
the center of the garage door opener storage bin door
is depressed. When the proper combination has been
selected, the push button is reinstalled in the com-
partment and the compartment door is closed.
SUNGLASS STORAGE BIN
A sunglasses storage bin is included in the over-
head console. The storage bin is located near the rear
of the overhead console and is held in the closed posi-
tion by a latch that is integral to the storage bin
door. The interior of the bin is lined with a foam rub-
ber padding material to protect the sunglasses from
being scratched. Dampening springs that are located
on the back of the overhead console reading andcourtesy lamp housing contact the hinges of the sun-
glasses storage bin for a smooth opening action.
The sunglasses storage bin and door unit is avail-
able for service replacement. The hinge dampening
springs are serviced as a unit with the overhead con-
sole reading and courtesy lamp housing.
The sunglasses storage bin is opened by pressing
the latch on the rear edge of the door towards the
front of the vehicle, then pulling the bin downward to
the open position. The integral latch on the sun-
glasses bin door will automatically engage when the
bin is closed. See the owner's manual in the vehicle
glove box for more information on the use and oper-
ation of the sunglasses storage bin.
COMPASS
While in the compass/temperature mode, the com-
pass will display the direction in which the vehicle is
pointed using the eight major compass headings
(Examples: north is N, northeast is NE), along with
the outside ambient temperature. When the compass
unit is placed in the compass/compass in degrees
mode, the compass will display the direction the
vehicle is heading using the eight major compass
headings and in degrees (0 to 359 degrees). North is
0 degrees, East is 90 degrees, South is 180 degrees
and West is 270 degrees. It will not display the head-
ings in minutes or seconds.
The self-calibrating compass unit requires no
adjusting in normal use. The compass unit will com-
pensate for magnetism the body of the vehicle may
acquire during normal use. However, avoid placing
anything magnetic directly on the roof of the vehicle.
Magnetic mounts for an antenna, a repair order hat,
or a funeral procession flag can exceed the compen-
sating ability of the compass unit if placed on the
roof panel. If the vehicle roof should become magne-
tized, the demagnetizing and calibration procedures
found in this group may be required to restore proper
compass operation.
THERMOMETER
The thermometer displays the outside ambient
temperature in whole degrees. The temperature dis-
play can be changed from Fahrenheit to Celsius
1 - SUNGLASSES STORAGE BIN
2 - GARAGE DOOR OPENER STORAGE BIN DOOR
3 - COMPUTER LENS OR COVER PLUG
4 - HOOK AND LOOP FASTENER
5 - SECURITY INDICATOR LAMP
6 - COMPASS MINI-TRIP COMPUTER MODULE
7 - SCREW (3)
8 - SCREW (4)
9 - BULB HOLDERS10 - SWITCHES
11 - WIRE HARNESS
12 - SPRINGS (2)
13 - READING AND COURTESY LAMP HOUSING
14 - REFLECTORS
15 - OVERHEAD CONSOLE HOUSING
16 - LENSES
17 - BUMPER
18 - GARAGE DOOR OPENER PUSH BUTTON
BR/BEMESSAGE SYSTEMS 8M - 3
OVERHEAD CONSOLE (Continued)

using the U.S./Metric push button. The displayed
temperature is not an instant reading of conditions,
but an average temperature. It may take the ther-
mometer display several minutes to respond to a
major temperature change, such as driving out of a
heated garage into winter temperatures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the thermometer unit memory. When the ignition
switch is turned to the On position again, the ther-
mometer will display the memory temperature if the
engine coolant temperature is above about 43É C
(109É F). If the engine coolant temperature is below
about 43É C (109É F), the thermometer will display
the actual temperature sensed by the ambient tem-
perature sensor. The thermometer temperature dis-
play update interval varies with the vehicle speed;
therefore, if the temperature reading seems inaccu-
rate, drive the vehicle for at least three minutes
while maintaining a speed of 48 kilometers-per-hour
(30 miles-per-hour) or higher.
The thermometer function is supported by an
ambient temperature sensor. The sensor is mounted
outside the passenger compartment near the front
and center of the vehicle, and is hard wired to the
module. The ambient temperature sensor is available
as a separate service item.
STANDARD PROCEDURE
STANDARD PROCEDURE - COMPASS
CALIBRATION
CAUTION: Do not place any external magnets, such
as magnetic roof mount antennas, in the vicinity of
the compass. Do not use magnetic tools when ser-
vicing the overhead console.
The electronic compass unit features a self-cali-
brating design, which simplifies the calibration pro-
cedure. This feature automatically updates the
compass calibration while the vehicle is being driven.
This allows the compass unit to compensate for small
changes in the residual magnetism that the vehicle
may acquire during normal use. If the compass read-
ings appear to be erratic or out of calibration, per-
form the following calibration procedure. Also, new
service replacement compass mini-trip computer
modules must have their compass calibrated using
this procedure. Do not attempt to calibrate the com-
pass near large metal objects such as other vehicles,
large buildings, or bridges; or, near overhead or
underground power lines.
(1) Start the engine. If the compass/temperature
data is not currently being displayed, momentarily
depress and release the Step push button to stepthrough the display options until you have reached
the compass/temperature display.
(2) Depress both the U.S./Metric and the Step
push buttons at the same time for more than six sec-
onds, until ªCALº appears in the display, then release
both push buttons. The ªCALº in the display indi-
cates that the compass is in the calibration mode.
(3) Drive the vehicle on a level surface, at least
fifty feet away from large metal objects and power
lines, in all four compass directions, such as driving
around a city block several times or driving in two to
three complete circles at a slow to medium speed.
(4) When the calibration is successfully completed,
ªCALº will disappear from the display and normal
compass mini-trip computer operation will resume.
NOTE: If the ªCALº message remains in the display,
either there is excessive magnetism near the com-
pass, or the unit is faulty. Repeat the calibration
procedure at least one more time.
NOTE: If the wrong direction is still indicated in the
compass display, the area selected for calibration
may be too close to a strong magnetic field. Repeat
the calibration procedure in another location.
STANDARD PROCEDURE - COMPASS
VARIATION ADJUSTMENT
Compass variance, also known as magnetic decli-
nation, is the difference in angle between magnetic
north and true geographic north. In some geographic
locations, the difference between magnetic and geo-
graphic north is great enough to cause the compass
to give false readings. If this problem occurs, the
compass variance must be set. There are two meth-
ods that can be used to enter this information into
the compass mini-trip computer module. They are
the zone method and the direct method.
ZONE METHOD
(1) Using the Variance Settings map, find your
geographic location and note the zone number (Fig.
2).
(2) Turn the ignition switch to the On position. If
the compass/temperature data is not currently being
displayed, momentarily depress and release the Step
push button to step through the display options until
you have reached the compass/temperature display.
(3) Depress both the U.S./Metric and the Step
push buttons at the same time and hold them down
for more than 100 milliseconds, but not more than
one second. The compass mini-trip computer will
enter the variation adjustment mode and ªVARº
along with the current variance zone will appear in
the display.
8M - 4 MESSAGE SYSTEMSBR/BE
OVERHEAD CONSOLE (Continued)

(4) Momentarily depress and release the Step push
button to step through the zone numbers, until the
zone number for your geographic location appears in
the display.
(5) After five seconds, the displayed zone will auto-
matically be set in the compass mini-trip computer
module memory and normal operation will resume.
(6) Confirm that the correct directions are now
indicated by the compass.
DIRECT METHOD
(1) Turn the vehicle so it is headed in either the
north or south direction. The vehicle must be headed
within 45 degrees of north or south for this procedure
to work. The vehicle may be moving or stationary.
(2) Turn the ignition switch to the On position. If
the compass/temperature data is not currently being
displayed, momentarily depress and release the Step
push button to step through the display options until
you have reached the compass/temperature display.
(3) Depress both the U.S./Metric and the Step
push buttons at the same time and hold them down
for more than 100 milliseconds, but not more than
one second. The compass mini-trip computer will
enter the variation adjustment mode and ªVARº
along with the current variance zone will appear in
the display.
(4) Within the next five seconds, momentarily
depress and release the U.S./Metric push button. The
variance zone will automatically be set in the com-pass mini-trip computer module memory and normal
operation will resume.
(5) If the ªVARº in the display flashes twice before
the compass mini-trip computer module resumes nor-
mal operation, the new variance zone setting was not
accepted. Reorient the vehicle so it is headed within
45 degrees of north or south and repeat this proce-
dure.
STANDARD PROCEDURE - COMPASS
DEMAGNETIZING
A degaussing tool (Special Tool 6029) is used to
demagnetize, or degauss, the overhead console for-
ward mounting screw and the roof panel above the
overhead console. Equivalent units must be rated as
continuous duty for 110/115 volts and 60 Hz. They
must also have a field strength of over 350 gauss at 7
millimeters (0.25 inch) beyond the tip of the probe.
To demagnetize the roof panel and the overhead
console forward mounting screw, proceed as follows:
(1) Be certain that the ignition switch is in the Off
position, before you begin the demagnetizing proce-
dure.
(2) Connect the degaussing tool to an electrical
outlet, while keeping the tool at least 61 centimeters
(2 feet) away from the compass unit.
(3) Slowly approach the head of the overhead con-
sole forward mounting screw with the degaussing
tool connected.
Fig. 2 Variance Settings
BR/BEMESSAGE SYSTEMS 8M - 5
OVERHEAD CONSOLE (Continued)