ECO mode DODGE RAM 2001 Service Owner's Guide

²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal (in the distribu-
tor)
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
Based on these inputs the following occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off.
²The PCM adjusts engine idle speed through the
idle air control (IAC) motor and adjusts ignition tim-
ing.
²The PCM operates the A/C compressor clutch
through the clutch relay. This is done if A/C has been
selected by the vehicle operator and requested by the
A/C thermostat.
²When engine has reached operating tempera-
ture, the PCM will begin monitoring O2S sensor
input. The system will then leave the warm-up mode
and go into closed loop operation.
IDLE MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At idle speed, the PCM
receives inputs from:
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
²Battery voltage
²Crankshaft position sensor
²Engine coolant temperature sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal (in the distribu-
tor)
²Battery voltage
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Oxygen sensors
Based on these inputs, the following occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
injection sequence and injector pulse width by turn-
ing the ground circuit to each individual injector on
and off.
²The PCM monitors the O2S sensor input and
adjusts air-fuel ratio by varying injector pulse width.
It also adjusts engine idle speed through the idle air
control (IAC) motor.
²The PCM adjusts ignition timing by increasing
and decreasing spark advance.²The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.
CRUISE MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At cruising speed, the PCM
receives inputs from:
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
²Battery voltage
²Engine coolant temperature sensor
²Crankshaft position sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal (in the distribu-
tor)
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Oxygen (O2S) sensors
Based on these inputs, the following occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then adjust
the injector pulse width by turning the ground circuit
to each individual injector on and off.
²The PCM monitors the O2S sensor input and
adjusts air-fuel ratio. It also adjusts engine idle
speed through the idle air control (IAC) motor.
²The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
²The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.
ACCELERATION MODE
This is an Open Loop mode. The PCM recognizes
an abrupt increase in throttle position or MAP pres-
sure as a demand for increased engine output and
vehicle acceleration. The PCM increases injector
pulse width in response to increased throttle opening.
DECELERATION MODE
When the engine is at operating temperature, this
is an Open Loop mode. During hard deceleration, the
PCM receives the following inputs.
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
²Battery voltage
²Engine coolant temperature sensor
²Crankshaft position sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
8E - 16 ELECTRONIC CONTROL MODULESBR/BE
POWERTRAIN CONTROL MODULE (Continued)

(4) Clean the battery cable terminal clamps and
the battery terminal posts. Refer toBattery System
in this group for the location of the proper battery
system cleaning and inspection procedures.
(5) Reconnect the battery positive cable terminal
clamp to the battery positive terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 4 N´m (35
in. lbs.).
(6) Reconnect the battery negative cable terminal
clamp to the battery negative terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 4 N´m (35
in. lbs.).
(7) Apply a thin coating of petroleum jelly or chas-
sis grease to the exposed surfaces of the battery cable
terminal clamps and the battery terminal posts.
BATTERY HOLDDOWN
DESCRIPTION
The battery hold down hardware (Fig. 18) includes
two bolts, two U-nuts and a hold down strap. The bat-
tery hold down bracket consists of a formed steel rod
with a stamped steel angle bracket welded to each end.
The hold down bracket assembly is then plastic-coated
for corrosion protection. Models equipped with the
optional diesel engine have a second battery installed
in a second battery tray on the right side of the engine
compartment. The hold down hardware for the rightside battery is mirror image of the hold down hard-
ware used for the left side battery.
When installing a battery into the battery tray, be
certain that the hold down hardware is properly
installed and that the fasteners are tightened to the
proper specifications. Improper hold down fastener
tightness, whether too loose or too tight, can result in
damage to the battery, the vehicle or both. Refer to
Battery Hold Downsin this group for the location
of the proper battery hold down installation proce-
dures, including the proper hold down fastener tight-
ness specifications.
OPERATION
The battery holddown secures the battery in the
battery tray. This holddown is designed to prevent
battery movement during the most extreme vehicle
operation conditions. Periodic removel and lubrica-
tion of the battery holddown hardware is recomended
to prevent hardware seizure at a later date.
NOTE: Never operate a vehicle without a battery
holddown device properly installed. Damage to the
vehicle, components and battery could result.
REMOVAL
All of the battery hold down hardware except for
the outboard U-nut can be serviced without removal
of the battery or the battery tray. The battery tray
must be removed from the vehicle to service the out-
board U-nut. If the outboard U-nut requires service
replacement, refer toBattery Trayin the index of
this service manual for the location of the proper bat-
tery tray removal and installation procedures.
(1) Turn the ignition switch to the Off position. Be
certain that all electrical accessories are turned off.
(2) Loosen the battery negative cable terminal
clamp pinch-bolt hex nut.
(3) Disconnect the battery negative cable terminal
clamp from the battery negative terminal post. If
necessary, use a battery terminal puller to remove
the terminal clamp from the battery post.
(4) Remove the two battery hold down bolts from
the battery hold down strap (Fig. 19) .
(5) Remove the battery hold down strap from the
top of the battery case.
INSTALLATION
All of the battery hold down hardware except for
the outboard U-nut can be serviced without removal
of the battery or the battery tray. The battery tray
must be removed from the vehicle to service the out-
board U-nut. If the outboard U-nut requires service
replacement, refer toBattery Trayin the index of
this service manual for the location of the proper bat-
tery tray removal and installation procedures.
Fig. 18 Battery Hold Downs - Typical
1 - BATTERY TRAY
2 - U-NUT (2)
3 - BATTERY
4 - BOLT (2)
5 - STRAP
8F - 18 BATTERY SYSTEMBR/BE
BATTERY (Continued)

(1) Clean and inspect the battery hold down hard-
ware. Refer toBatteryin the index of this service
manual for the location of the proper battery hold
down hardware cleaning and inspection procedures.
(2) Position the battery hold down strap across the
top of the battery case.
(3) Install and tighten the two battery hold down
bolts through the holes on each end of the hold down
strap and into the U-nuts on each side of the battery
tray. Tighten the bolts to 4 N´m (35 in. lbs.).
(4) Reconnect the battery negative cable terminal
clamp to the battery negative terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 4 N´m (35
in. lbs.).
BATTERY CABLE
DESCRIPTION
The battery cables (Fig. 20) are large gauge,
stranded copper wires sheathed within a heavy plas-
tic or synthetic rubber insulating jacket. The wire
used in the battery cables combines excellent flexibil-
ity and reliability with high electrical current carry-
ing capacity. Refer toWiring Diagramsin the index
of this service manual for the location of the proper
battery cable wire gauge information.The battery cables cannot be repaired and, if dam-
aged or faulty they must be replaced. Both the bat-
tery positive and negative cables are available for
service replacement only as a unit with the battery
positive cable wire harness or the battery negative
cable wire harness, which may include portions of
the wiring circuits for the generator and other com-
ponents on some models. Refer toWiring Diagrams
in the index of this service manual for the location of
more information on the various wiring circuits
included in the battery cable wire harnesses for the
vehicle being serviced.
GASOLINE ENGINE
Gasoline engine models feature a stamped brass
clamping type female battery terminal crimped onto
one end of the battery cable wire and then solder-
dipped. A square headed pinch-bolt and hex nut are
installed at the open end of the female battery termi-
nal clamp. The battery positive cable also includes a
red molded rubber protective cover for the female
battery terminal clamp. Large eyelet type terminals
are crimped onto the opposite end of the battery
cable wire and then solder-dipped. The battery posi-
tive cable wires have a red insulating jacket to pro-
vide visual identification and feature a larger female
battery terminal clamp to allow connection to the
larger battery positive terminal post. The battery
negative cable wires have a black insulating jacket
and a smaller female battery terminal clamp.
Fig. 19 Left Battery Hold Downs Remove/Install -
Typical for Right Battery
1 - BATTERY TRAY
2 - U-NUT (2)
3 - BATTERY
4 - BOLT (2)
5 - STRAP
Fig. 20 Battery Cables - Typical
1 - EYELET
2 - NUT
3 - POWER DISTRIBUTION CENTER
4 - POSITIVE CABLE
5 - SCREW
6 - NEGATIVE CABLE
7 - EYELET
8 - CLIP
BR/BEBATTERY SYSTEM 8F - 19
BATTERY HOLDDOWN (Continued)

NEGATIVE CABLE INSTALLATION - GASOLINE
(1) Position the battery wire harness into the
engine compartment and under the compressor
mounting bracket, if equipped.
(2) Install and tighten the nut that secures the
battery negative cable ground eyelet terminal to the
stud on the power steering pump pivot bolt.
(3) Install the generator output cable eyelet termi-
nal onto the generator output terminal stud.
(4) Install and tighten the nut that secures the
generator output cable eyelet terminal to the genera-
tor output terminal stud. Tighten the nut to 8.4 N´m
(75 in. lbs.).
(5) Position the cover for the generator output ter-
minal stud housing onto the back of the generator
and snap it into place.
(6) Secure wire assembly in place with pushpin
retainers in there original positions.
(7) Install and tighten the screw that secures the
battery negative cable eyelet terminal to the radiator
closure panel, near the battery. Tighten the screw to
40 in. lbs.
(8) Install and tighten the screw that secures the
battery negative cable eyelet terminal to the left
front side of the frame assembly. Tighten the screw
to 80 in. lbs.
(9) Install and tighten the nut that secures the
battery positive cable eyelet terminal and the gener-
ator output cable eyelet terminal to the PDC B(+)
terminal stud. Tighten the nut to 80 in. lbs.
(10) Reconnect the battery negative cable terminal
clamp to the battery negative terminal post. Tighten
the terminal clamp pinch-bolt hex nut to 35 in. lbs.
(11)
Apply a thin coating of petroleum jelly or chassis
grease to the exposed surfaces of the battery cable ter-
minal clamps and the battery terminal posts.
BATTERY TRAY
DESCRIPTION
The battery is mounted in a molded plastic tray (Fig.
26) with an integral support located in the left front cor-
ner of the engine compartment. A U-nut held in a
molded formation on each side of the battery tray pro-
vides anchor points for the battery hold down bolts. The
battery tray is secured on the outboard side to the inner
fender shield by two hex screws with washers, and from
underneath the integral battery tray support is secured
to the left front wheelhouse inner panel by two stud
plates. Each stud plate has two studs and is secured by
two nuts with washers. The stud plate that secures the
front of the battery tray support to the wheelhouse innerpanel is installed through the wheelhouse panel from
the top. The stud plate that secures the rear of the bat-
tery tray support to the wheelhouse inner panel is
installed through the wheelhouse panel from the bottom.
A hole in the bottom of the battery tray is fitted
with a battery temperature sensor. Refer toBattery
Temperature Sensorin the index of this service
manual for the location of more information on the
battery temperature sensor. Models that are
equipped with an optional vehicle speed control sys-
tem have the speed control servo secured to the inte-
gral battery tray support. Refer toSpeed Control
Servoin the index of this service manual for the
location of more information on the speed control
servo and its mounting.
Models that are equipped with the diesel engine
option have a second battery tray located in the right
front corner of the engine compartment. This second
battery tray and its mounting are mirror image of
the standard equipment left battery tray. However,
the right battery tray and support have no provisions
for a battery temperature sensor or a speed control
servo mounting bracket.
Fig. 26 Battery Tray - Typical
1 - STUD PLATE (2)
2 - NUT AND WASHER (4)
3 - FRONT WHEELHOUSE INNER PANEL
4 - SPEED CONTROL SERVO
5 - TRAY
6 - SCREW AND WASHER (2)
7 - BATTERY TREMPERATURE SENSOR
8 - U-NUT (2)
9 - FENDER INNER SHIELD
8F - 24 BATTERY SYSTEMBR/BE
BATTERY CABLE (Continued)

OPERATION
The heated seat module receives fused battery cur-
rent through the energized heated seat relay in the
Junction Block (JB) only when the engine is running.
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
only when the ignition switch is in the On position.
The heated seat module shares a common ground cir-
cuit with each of the heated seat elements. The
heated seat elements will only operate when the sur-
face temperature of the seat cushion cover at the
heated seat sensors is below the designed tempera-
ture set points of the system.
The heated seat module will automatically turn off
the heated seat elements if it detects a short in the
heated seat element circuit or a heated seat sensor
value that is out of range. The heated seat system
will also be turned off automatically whenever the
ignition switch is turned to any position except On or
if the engine quits running. If the ignition switch is
turned to the Off position or if the engine quits run-
ning while a heated seat is turned ON, the heated
seat will remain Off after the engine is restarted
until a heated seat switch is depressed again.
The heated seat module monitors inputs from the
heated seat sensors and the heated seat switches. In
response to these inputs the heated seat module uses
its internal programming to control outputs to the
heated seat elements in both front seats and to con-
trol the heated seat LED indicator lamps located in
both of the heated seat switches. The heated seat
module is also programmed to provide a self-diagnos-
tic capability. When the module detects certain fail-
ures within the heated seat system, it will provide a
visual indication of the failure by flashing the indica-
tor lamps in the heated seat switches.
DIAGNOSIS & TESTING - HEATED SEAT
SYSTEM
SELF-DIAGNOSIS
The heated seat system is capable of performing
some self-diagnostics. The following table depicts the
various failure modes which will be reported to the
vehicle operator or technician by flashing the individ-
ual heated seat switch Light Emitting Diode (LED)
indicator lamps. See the Heated Seat System Self-Di-
agnosis table for the diagnostic routines. The driver
side heated seat switch indicator lamps will flash if a
failure occurs in the driver side heated seat, and the
passenger side heated seat switch indicator lamps
will flash for a passenger side heated seat failure. If
a monitored heated seat system failure occurs, the
switch indicator lamps will flash at a pulse rate of
about one-half second on, followed by about one-half
second off for a duration of about one minute afterthe switch for the faulty heated seat is depressed in
either the Low or High direction. This process will
repeat every time the faulty heated seat switch is
actuated until the problem has been corrected.
Heated Seat System Self-Diagnosis
Monitored FailureSwitch High
Indicator LampSwitch Low
Indicator Lamp
Heated Seat
Element ShortedFlashing Flashing
Heated Seat
Element OpenFlashing Off
Heated Seat
Sensor Value Out
of RangeOff Flashing
TESTING
Refer toPower Seatin the index of this service
manual for the location of complete heated seat sys-
tem wiring diagrams. Before testing the individual
components in the heated seat system, perform the
following preliminary checks:
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.
²If the heated seat switch back lighting and the
cluster illumination lamps do not illuminate with the
headlamps or park lamps turned On, refer toInstru-
ment Clusterin the index of this service manual for
the location of the proper cluster illumination lamps
diagnosis and testing procedures. If the heated seat
switch back lighting does not illuminate, but the
cluster illumination lamps do illuminate with the
headlamps or park lamps turned On, refer to
Heated Seat Switchin this section for the location
of the proper heated seat switch diagnosis and test-
ing procedure.
²If a single indicator lamp for one heated seat
switch does not operate and the heated seat elements
do heat, refer toHeated Seat Switchin this section
for the location of the proper heated seat switch diag-
nosis and testing procedure.
8G - 6 HEATED SEAT SYSTEMBR/BE
HEATED SEAT SYSTEM (Continued)

²If both indicator lamps for a heated seat switch
operate, but the heated seat elements do not heat,
refer toHeated Seat Modulein Electronic Control
Modules for the location of the proper heated seat
module diagnosis and testing procedures. Also refer
to the Body Diagnostic Manual for additional diagno-
sis and testing procedures.
²If none of the indicator lamps for both heated
seat switches will operate and the heated seat ele-
ments for both seats do not heat, refer toHeated
Seat Relayin this section for the location of the
proper heated seat relay diagnosis and testing proce-
dures.
²If the an indicator lamp on either heated seat
switch remains illuminated after the heated seat has
been turned Off, refer toHeated Seat Modulein
Electronic Control Modules for the location of the
proper heated seat module diagnosis and testing pro-
cedures. Also refer to the Body Diagnostic Manual for
additional diagnosis and testing procedures.
DRIVER SEAT HEATER
SWITCH
DESCRIPTION
The heated seat switches used on vehicles with
this option are both mounted in a heated seat switch
bezel (Fig. 2), which replaces the standard equipmentcubby bin located in the lower right corner of the
instrument cluster bezel next to the radio receiver.
The two switches are snapped into the mounting
holes of the heated seat switch bezel, and the heated
seat switch bezel is secured with three screws to the
instrument panel. The mounts for the heated seat
switch bezel are concealed behind the instrument
cluster bezel. The two heated seat switches are iden-
tical in appearance and construction, except for the
location of a keyway in the single connector recepta-
cle on the back of each switch. The instrument panel
wire harness connectors for the heated seat switches
are keyed to match the connector receptacles on the
switches so that the two heated seat switches can
only be connected to the proper heated seat.
The momentary, bidirectional rocker-type heated
seat switch provides a resistor-multiplexed signal to
the heated seat module. Each switch has a center
neutral position and momentary Low and High posi-
tions so that both the driver and the front seat pas-
senger can select a preferred seat heating mode.
Each heated seat switch has two Light-Emitting
Diode (LED) indicator lamps, which indicate the
selected mode (Low or High) of the seat heater for
each seat and to provide diagnostic feedback for the
heated seat system. Each switch also has an incan-
descent bulb, which provides panel lamps dimmer
controlled back lighting of the switch nomenclature
when the headlamps or park lamps are turned on.
The two LED indicator lamps and the incandescent
bulb in each heated seat switch cannot be repaired. If
the indicator lamps or back lighting bulb are faulty
or damaged, the individual heated seat switch unit
must be replaced.
OPERATION
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
when the ignition switch is in the On position.
Depressing the heated seat switch rocker to its
momentary High or Low position provides a hard-
wired resistor multiplexed voltage request signal to
the heated seat module to power the heated seat ele-
ment of the selected seat and maintain the requested
temperature setting. If the heated seat switch is
depressed to a different position (Low or High) than
the currently selected state, the heated seat module
will change states to support the new selection. If a
heated seat switch is depressed a second time to the
same position as the currently selected state, the
heated seat module interprets the second input as a
request to turn the seat heater off. The heated seat
module will then turn the heated seat elements for
that seat off.
Fig. 2 Heated Seat Switches
1 - DRIVER SIDE SWITCH
2 - PASSENGER SIDE SWITCH
3 - INDICATOR LAMPS
4 - HEATED SEAT SWITCH BEZEL
BR/BEHEATED SEAT SYSTEM 8G - 7
HEATED SEAT SYSTEM (Continued)

The momentary, bidirectional rocker-type heated
seat switch provides a resistor-multiplexed signal to
the heated seat module. Each switch has a center
neutral position and momentary Low and High posi-
tions so that both the driver and the front seat pas-
senger can select a preferred seat heating mode.
Each heated seat switch has two Light-Emitting
Diode (LED) indicator lamps, which indicate the
selected mode (Low or High) of the seat heater for
each seat and to provide diagnostic feedback for the
heated seat system. Each switch also has an incan-
descent bulb, which provides panel lamps dimmer
controlled back lighting of the switch nomenclature
when the headlamps or park lamps are turned on.
The two LED indicator lamps and the incandescent
bulb in each heated seat switch cannot be repaired. If
the indicator lamps or back lighting bulb are faulty
or damaged, the individual heated seat switch unit
must be replaced.
OPERATION
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
when the ignition switch is in the On position.
Depressing the heated seat switch rocker to its
momentary High or Low position provides a hard-
wired resistor multiplexed voltage request signal to
the heated seat module to power the heated seat ele-
ment of the selected seat and maintain the requestedtemperature setting. If the heated seat switch is
depressed to a different position (Low or High) than
the currently selected state, the heated seat module
will change states to support the new selection. If a
heated seat switch is depressed a second time to the
same position as the currently selected state, the
heated seat module interprets the second input as a
request to turn the seat heater off. The heated seat
module will then turn the heated seat elements for
that seat off.
The indicator lamps in the heated seat switches
receive battery current through a fused ignition
switch output (run) circuit when the ignition switch
is in the On position. The ground side of each indi-
cator lamp is controlled by a separate (high or low/
driver or passenger) indicator lamp driver circuit by
the heated seat module. The heated seat module con-
trol of the switch indicator lamps also allows the
module to provide diagnostic feedback to the vehicle
operator to indicate monitored heated seat system
faults by flashing the indicator lamps on and off. One
side of the incandescent back lighting bulb in each
heated seat switch is connected to ground at all
times. The other side of the incandescent bulb is con-
nected to the fused panel lamps dimmer switch sig-
nal circuit. These bulbs are energized when the park
lamps or headlamps are turned on, and their illumi-
nation intensity is controlled by the panel lamps dim-
mer switch.
DIAGNOSIS & TESTING - HEATED SEAT
SWITCH
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams.
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) If the problem being diagnosed involves inoper-
ative heated seat switch back lighting and the cluster
illumination lamps operate, go to Step 2. If the prob-
lem being diagnosed involves inoperative heated seat
switch back lighting and the cluster illumination
lamps are also inoperative, refer toInstrument
Fig. 9 Heated Seat Switches
1 - DRIVER SIDE SWITCH
2 - PASSENGER SIDE SWITCH
3 - INDICATOR LAMPS
4 - HEATED SEAT SWITCH BEZEL
8G - 14 HEATED SEAT SYSTEMBR/BE
PASSENGER SEAT HEATER SWITCH (Continued)

The EMIC circuitry operates on battery current
received through a fused B(+) fuse in the Junction
Block (JB) on a non-switched fused B(+) circuit, and
on battery current received through a fused ignition
switch output (st-run) fuse in the JB on a fused igni-
tion switch output (st-run) circuit. This arrangement
allows the EMIC to provide some features regardless
of the ignition switch position, while other features
will operate only with the ignition switch in the Start
or On positions. The EMIC circuitry is grounded
through two separate ground circuits located in one
of the two instrument cluster connectors and take
outs of the instrument panel wire harness. One
ground circuit receives ground through a take out
with an eyelet terminal connector of the instrument
panel wire harness that is secured by a nut to a
ground stud located on the left instrument panel end
bracket, while the other ground circuit receives
ground through a take out with an eyelet terminal
connector of the instrument panel wire harness that
is secured by a nut to a ground stud located on the
back of the instrument panel armature above the
inboard side of the instrument panel steering column
opening.
The EMIC also has a self-diagnostic actuator test
capability, which will test each of the CCD bus mes-
sage-controlled functions of the cluster by lighting
the appropriate indicators and positioning the gauge
needles at several predetermined locations on the
gauge faces in a prescribed sequence. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). See the owner's manual in the
vehicle glove box for more information on the fea-
tures, use and operation of the EMIC.
GAUGES
All gauges receive battery current through the
EMIC circuitry when the ignition switch is in the On
or Start positions. With the ignition switch in the Off
position battery current is not supplied to any
gauges, and the EMIC circuitry is programmed to
move all of the gauge needles back to the low end of
their respective scales. Therefore, the gauges do not
accurately indicate any vehicle condition unless the
ignition switch is in the On or Start positions. All of
the EMIC gauges, except the odometer, are air core
magnetic units. Two fixed electromagnetic coils are
located within each gauge. These coils are wrapped
at right angles to each other around a movable per-
manent magnet. The movable magnet is suspended
within the coils on one end of a pivot shaft, while the
gauge needle is attached to the other end of the
shaft. One of the coils has a fixed current flowing
through it to maintain a constant magnetic fieldstrength. Current flow through the second coil
changes, which causes changes in its magnetic field
strength. The current flowing through the second coil
is changed by the EMIC circuitry in response to mes-
sages received over the CCD data bus. The gauge
needle moves as the movable permanent magnet
aligns itself to the changing magnetic fields created
around it by the electromagnets.
The gauges are diagnosed using the EMIC self-di-
agnostic actuator test. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). Proper testing of the CCD data bus and
the data bus message inputs to the EMIC that con-
trol each gauge require the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
Specific operation details for each gauge may be
found elsewhere in this service manual.
VACUUM-FLUORESCENT DISPLAY
The Vacuum-Fluorescent Display (VFD) module is
soldered to the EMIC circuit board. The display is
active with the ignition switch in the On or Start
positions, and inactive when the ignition switch is in
any other position. The VFD has several display
capabilities including odometer, trip odometer, and
an amber ªCRUISEº indication whenever the
optional speed control system is turned On. The
cruise indicator function of the VFD is automatically
enabled or disabled by the EMIC circuitry based
upon whether the vehicle is equipped with the speed
control option. An odometer/trip odometer switch on
the EMIC circuit board is used to control several of
the display modes. This switch is actuated manually
by depressing the odometer/trip odometer switch
knob that extends through the lower edge of the clus-
ter lens, just right of center. Actuating this switch
momentarily with the ignition switch in the On posi-
tion will toggle the VFD between the odometer and
trip odometer modes. The word ªTRIPº will also
appear in blue-green text when the VFD trip odome-
ter mode is active. Depressing the switch button for
about two seconds while the VFD is in the trip odom-
eter mode will reset the trip odometer value to zero.
Holding this switch depressed while turning the igni-
tion switch from the Off position to the On position
will activate the EMIC self-diagnostic actuator test.
The EMIC will automatically flash the odometer or
trip odometer information on and off if there is a loss
of CCD data bus communication. The VFD will also
display various information used in several diagnos-
tic procedures. Refer to the appropriate diagnostic
information for additional details on this VFD func-
tion.
8J - 4 INSTRUMENT CLUSTERBR/BE
INSTRUMENT CLUSTER (Continued)

(7) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Reinstall the instrument cluster. Reconnect the bat-
tery negative cable. Turn the ignition switch to the
On position. Set the park brake. The brake indicator
in the instrument cluster should light. If OK, go to
Step 8. If not OK, go to Step 9.
(8) Turn the ignition switch to the Off position.
Turn on the park lamps and adjust the panel lamps
dimmer thumbwheel in the headlamp switch to the
full bright position. The cluster illumination lamps
should light. If OK, go to Step 10. If not OK, repair
the open ground circuit (Z3) between the instrument
cluster and ground (G201) as required.
(9) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster. Connect the battery
negative cable. Turn the ignition switch to the On
position. Check for battery voltage at the fused igni-
tion switch output (st-run) circuit cavity of the
instrument panel wire harness connector (Connector
C1). If OK, refer to ACTUATOR TEST . If not OK,
repair the open fused ignition switch output (st-run)
circuit between the instrument cluster and the JB as
required.
(10) Disconnect and isolate the battery negative
cable. Remove the instrument cluster. Check for con-
tinuity between the ground circuit (Z2) cavity of the
instrument panel wire harness connector (Connector
C1) and a good ground. There should be continuity. If
OK, refer to ACTUATOR TEST . If not OK, repair
the open ground circuit to ground (G200) as required.
ACTUATOR TEST
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.
The instrument cluster actuator test will put the
instrument cluster into its self-diagnostic mode. In
this mode the instrument cluster can perform a self-
diagnostic test that will confirm that the instrument
cluster circuitry, the gauges, and the CCD data bus
message-controlled indicators are capable of operat-
ing as designed. During the actuator test the instru-
ment cluster circuitry position each of the gauge
needles at various calibration points, illuminate each
of the segments in the Vacuum-Fluorescent Display
(VFD), and turn all of the CCD data bus message-
controlled indicators on and off.
Successful completion of the actuator test will con-
firm that the instrument cluster is operational. How-
ever, there may still be a problem with the CCD data
bus, the Powertrain Control Module (PCM), the
Engine Control Module (ECM), the Airbag Control
Module (ACM), the Controller Anti-lock Brake (CAB),
or the inputs to one of these electronic control mod-
ules. Use a DRBIIItscan tool to diagnose these com-
ponents. Refer to the appropriate diagnostic
information.
(1) Begin the test with the ignition switch in the
Off position.
(2) Depress the odometer/trip odometer switch but-
ton.
(3) While still holding the odometer/trip odometer
switch button depressed, turn the ignition switch to
the On position, but do not start the engine.
(4) Keep the odometer/trip odometer switch button
depressed for about ten seconds, untilCHEC
appears in the odometer display, then release the
odometer/trip odometer switch button.
(5) A series of three-digit numeric failure messages
may appear in the odometer display, depending upon
the failure mode. If a failure message appears, refer
to the Instrument Cluster Failure Message chart for
the description and proper correction. If no failure
message appears, the actuator test will proceed as
described in Step 6.
BR/BEINSTRUMENT CLUSTER 8J - 7
INSTRUMENT CLUSTER (Continued)

INSTRUMENT CLUSTER FAILURE MESSAGE
Message Description Correction
110 A failure has been identified in the cluster
CPU, RAM, or EEPROM.1. Replace the faulty cluster.
900 The CCD data bus is not operational. 1. Check the CCD data bus connections at the
cluster.
2. Check the cluster fuses.
3. Check the CCD data bus bias.
4. Check the CCD data bus voltage.
5. Check the CCD data bus terminations.
920 The cluster is not receiving a vehicle speed
message from the PCM.1. Check the PCM software level and reflash if
required.
2. Use a DRBIIITscan tool to verify that the
vehicle speed message is being sent by the
PCM.
921 The cluster is not receiving a distance pulse
message from the PCM.1. Check the PCM software level and reflash if
required.
2. Use a DRBIIITscan tool to verify that the
distance pulse message is being sent by the
PCM.
940 The cluster is not receiving an airbag lamp-on
message from the ACM.1. Check the CCD data bus connections at the
ACM.
2. Check the ACM fuse.
950 The cluster is not receiving an ABS lamp-on
message from the CAB.1. Check the CCD data bus connections at the
CAB.
2. Check the CAB fuse.
999 An error has been discovered. 1. Record the failure message.
2. Depress the trip odometer reset button to
continue the Self-Diagnostic Test.
(6) The instrument cluster will begin the Vacuum
Fluorescent Display (VFD) walking segment test.
This test will require the operator to visually inspect
each VFD segment as it is displayed to determine a
pass or fail condition. First, all of the segments will
be illuminated at once; then, each individual segment
of the VFD will be illuminated in sequence. If any
segment in the display fails to illuminate, repeat the
test to confirm the failure. If the failure is confirmed,
replace the faulty instrument cluster. Following com-
pletion of the VFD walking segment test, the actua-
tor test will proceed as described in Step 7.
(7) The instrument cluster will perform a bulb
check of each indicator that the instrument cluster
circuitry controls. If the wait-to-start indicator does
not illuminate during this test, the instrument clus-
ter should be removed. However, check that the
incandescent bulb is not faulty and that the bulb
holder is properly installed on the instrument cluster
electronic circuit board before considering instrument
cluster replacement. If the bulb and bulb holder
check OK, replace the faulty instrument cluster.
Each of the remaining instrument cluster circuitrycontrolled indicators except the cruise indicator are
illuminated by a Light Emitting Diode (LED). If an
LED or the cruise indicator in the VFD, fails to illu-
minate during this test, the instrument cluster must
be replaced. Following the bulb check test, the actua-
tor test will proceed as described in Step 8.
(8) The instrument cluster will perform a gauge
actuator test. In this test the instrument cluster cir-
cuitry positions each of the gauge needles at three
different calibration points, then returns the gauge
needles to their relaxed positions. If an individual
gauge does not respond properly, or does not respond
at all during the gauge actuator test, the instrument
cluster should be removed. However, check that the
gauge terminal pins are properly inserted through
the spring-clip terminal pin receptacles on the instru-
ment cluster electronic circuit board before consider-
ing instrument cluster replacement. If the gauge
terminal connections are OK, replace the faulty
instrument cluster.
(9) The actuator test is now completed. The instru-
ment cluster will automatically exit the self-diagnos-
tic mode and return to normal operation at the
8J - 8 INSTRUMENT CLUSTERBR/BE
INSTRUMENT CLUSTER (Continued)