Dodge Ram. Manual - part 4

Park Lamp Relay

The park lamp switch is a direct input to the

instrument cluster. The instrument cluster sends a
PCI bus request to the FCM to actuate the park
lamp relay. The park lamp relay is then actuated
through the low side control circuit. This circuit is
electronically controlled and continuously moni-
tored for malfunctions.

Wiper High/Low Relay

The wiper switch is a direct input to the instru-

ment cluster. The instrument cluster sends a PCI
bus request to the FCM to actuate the wiper high/
low relay. The relay switches power between the low
speed and high speed of the wiper motor. The wiper
high/low relay is then actuated through the low side
control circuit. This circuit is electronically con-
trolled and continuously monitored for malfunc-
tions.

Wiper On/Off Relay

The wiper switch is a direct input to the instru-

ment cluster. The instrument cluster sends a PCI
bus request to the FCM to actuate the wiper on/off
relay. The wiper on/off relay is then actuated
through the low side control circuit. This relay
switches power to the wiper high/low relay. This
circuit is electronically controlled and continuously
monitored for malfunctions.

3.8.3

ELECTRICAL INPUTS

Module Battery Supply

12 Volt input for all FCM functions except head-

lamp operation.

Power Ground

Ground source for all FCM functions

Ignition Switch RUN or START Position
Status

12 volt input to inform the FCM of the ignition

switch status for related FCM functions.

PCI Bus

Approximately 7.5 volt input to allow the FCM to

communicate with other modules on the PCI bus.

Wiper Park Switch

Ground input used to determine the park place-

ment of the wipers. The ground is also used as
feedback to the FCM to determine wiper operating
mode.

Washer Fluid Level Switch

Ground input from the washer fluid level switch

which closes when washer fluid is low.

Battery (+) Connection Detection

12 volt supply used to monitor battery connection

to the IPM. The battery connection to the IPM uses
an internal switch to check integrity of the connec-
tion and that the Connector Positive Assurance
(CPA) is engaged. If the CPA is not properly en-
gaged, a voltage is sent to the FCM to be inter-
preted as an unseated connector which will set a
Diagnostic Trouble Code (DTC).

3.9

HEATING & A/C SYSTEM

3.9.1

SYSTEM AVAILABILITY

•

Depending on the model, either a Single-Zone or
Dual-Zone HVAC system is available in these
vehicles.

3.9.2

SYSTEM CONTROLS

The Heater Control Module:

•

is fully addressable with the DRBIII

•

communicates over the Programmable Commu-
nication Interface Multiplex System (PCI) Bus.

•

controls blower motor operation, providing four
blower speeds (Low, M1, M2, & High).

•

controls heated mirror and EBL operation (if
equipped).

•

controls electric door actuator operation.

The A/C-Heater Control Module:

•

is fully addressable with the DRBIII

•

communicates over the Programmable Commu-
nication Interface Multiplex System (PCI) Bus.

•

uses input from the evaporator temperature sen-
sor to prevent evaporator freeze up while main-
taining optimum cooling performance.

•

provides an A/C request to the Powertrain Con-
trol Module (PCM) over the PCI Bus when com-
pressor operation is desired.

•

controls blower motor operation, providing four
blower speeds (Low, M1, M2, & High).

•

controls heated mirror and EBL operation (if
equipped).

•

controls electric door actuator operation.

•

A simplified control system for operation of the
mode, recirculation, and temperature control
actuators provides positive positioning with-
out the complexity of feedback from position
sensors. The A/C - Heater Control Module
knows the number of operating actuator revo-
lutions required for full door travel as well as
the number of actuator commutator pulses per
revolution. Using these parameters, the A/C -
Heater Control Module runs the actuator for
the number of commutator pulses that corre-

GENERAL INFORMATION

spond to the desired door position. To maintain
accuracy, the system recalibrates itself period-
ically at known zero and full travel conditions.

The Single-Zone HVAC system uses:

•

one, two-wire electric blend door actuator.

•

two, two-wire electric mode door actuators.

•

one, two-wire electric recirculation door actuator.

The Dual-Zone HVAC system uses:

•

two, two-wire electric blend door actuators.

•

two, two-wire electric mode door actuators.

•

one, two-wire electric recirculation door actuator.

3.9.3

SYSTEM REVISIONS

The 2004 DR, HVAC system remains carryover
from 2003.

3.9.4

SYSTEM DIAGNOSTICS

Fault detection is through active and stored Diag-
nostic Trouble Codes (DTCs)

•

DTCs are displayed by the DRBIII

•

Active DTCs are those which currently exist in
the system. The condition causing the fault must
be repaired in order to clear this type of DTC.

•

Stored DTCs are those which occurred in the
system since the A/C-Heater Control Module re-
ceived the last

9clear diagnostic info9 message.

The A/C Cooldown Test:

•

is actuated with the DRBIII

•

checks A/C system performance based on evapo-
rator temperature sensor input.

•

will not run if ambient temperature is below
12.7°C (55°F).

•

will pass if the evaporator temperature drops
6.7°C (20°F) within two minutes of starting the
test.

•

faults display on the DRBIII

t as test messages

only after running the test.

•

faults will not display on the DRBIII

t as Diag-

nostic Trouble Codes.

•

will cause the A/C mode switch status indicator to
flash while the test is running.

•

If the test fails, the status indicator will con-
tinue to flash until either the test returns
passed or the ignition key is cycled. It will also
prevent the EBL mode switch status indicator
from indicating EBL operating status. How-
ever, the EBL mode switch will continue to
function in this state.

The HVAC Door Recalibration function:

•

is actuated with the DRBIII

•

monitors for door span faults.

•

faults display on the DRBIII

t as test messages

only after running the test.

•

faults will not display on the DRBIII

t as Diag-

nostic Trouble Codes.

•

will cause the EBL mode switch status indicator
to flash while the test is running.

•

If the test fails, the status indicator will con-
tinue to flash until either the test returns
passed or the ignition key is cycled. It will also
prevent the A/C mode switch status indicator
from indicating A/C operating status. How-
ever, the A/C mode switch will continue to
function in this state.

The Actuator Circuit Test:

•

is actuated with the DRBIII

•

monitors for shorted actuator circuits.

•

allows service to easily diagnose and troubleshoot
up to three simultaneous shorts.

•

supplements the continuous diagnostics on the
actuator drive system.

•

faults display on the DRBIII

t as test messages

only after running the test.

•

faults will not display on the DRBIII

t as Diag-

nostic Trouble Codes.

When Performing The Actuator Circuit Test

CAUTION: To ensure a proper diagnosis,
repair all Short Too Complex messages first,
all

common

door

driver

circuit

related

messages second, and all other door driver
circuit related messages last.

CAUTION: The DRBIII

can display up to

three Actuator Circuit Test messages at a
time. After repairing each Actuator Circuit
Test message, cycle the ignition switch, then
rerun the Actuator Circuit Test to ensure no
new messages exist.

•

The Short Too Complex message:

•

indicates that a specific determination of
which lines are shorted could not be made.

•

is caused by more than three drivers being
shorted in the same direction. For example,
four drivers all shorted to ground, or two or
more drivers shorted with at least one driver
shorted to ignition/battery and one driver
shorted to ground.

•

Messages displaying:

•

XXX

Driver/Circuit

Shorted

Ignition/

Battery will set on a per-driver basis.

•

XXX Driver/Circuit Shorted to Ground will set
on a per-driver basis.

•

the same two drivers/circuits shorted to

GENERAL INFORMATION

ignition/battery as-well-as shorted to ground
indicates that two actuator driver circuits are
shorted together.

•

When the test returns passed, then troubleshoot-
ing should proceed to clearing faults and running
the HVAC Door Recalibration system test as a
final check of system health.

3.10

INSTRUMENT CLUSTER

The DR Instrument Cluster is a new type of

control module that includes the hardware and
software necessary to function as the cluster and
the body control module. The Instrument Cluster
houses the Speedometer, Tachometer, Fuel gauge,
Coolant Temperature gauge, Oil Pressure gauge,
and the Voltage gauge. The cluster positions all of
the gauges using PCI bus messages received from
the PCM. The cluster contains certain warning
indicators, depending on engine type and options.
Some of the indicators are hardwire inputs and
some indicators are controlled via PCI bus mes-
sages. The warning chime tone generator is con-
tained within the cluster. The cluster includes a
vacuum fluorescent (VF) display for the PRNDL,
Total and Trip Odometers. The VF will also display
warning messages such as door ajar, low washer
fluid level, engine hours, and no bus communica-
tions. The cluster has the ability to set and store
DTCs, communicate on the PCI bus, display engine
information, and display certain inputs using the
DRBIII

The following systems are controlled either com-

pletely by the Instrument Cluster or in conjunction
with other inputs received by hardwire or via the
PCI bus:

•

Audible Warnings

•

Brake Lamp Control

•

Brake Transmission Shift Interlock (BTSI)

•

Cargo Lamp Control

•

Central Locking

•

Door Lock Inhibit

•

Enhanced Accident Response

•

Exterior Lighting Control

•

Exterior Lighting Fail-Safe

•

Heated Seat Control

•

Horn Control

•

Interior Lamp Control

•

Interior Lamps - Enhanced Accident Response

•

Interior Lamps Load Shedding

•

Lamp Out Indicator Control

•

Panel Lamps Dimming Control

•

Parade Mode

•

Power Locks

•

Remote Keyless Entry (RKE)

•

Remote Radio Switch Interface

•

Rolling Door Locks

•

Turn Signal and Hazard Warning Lamp Control

•

Vacuum Fluorescent Display Synchronization

•

Vehicle Theft Security System (VTSS)

CAUTION: Instrument clusters used in this
model automatically configure themselves
for

compatibility

with

the

features

and

optional equipment in the vehicle in which
they are initially installed. The instrument
cluster

programmed

this

embedding the Vehicle Identification Number
(VIN) and other information critical to proper
cluster operation in electronic memory. This
embedded information is learned through
electronic messages received from other
electronic modules in the vehicle over the
Programmable

Communications

Interface

(PCI) data bus, and through certain hard
wired inputs received when the cluster is
connected to the vehicle electrically.

Once

configured,

the

instrument

cluster

memory may be irreparably damaged and
certain irreversible configuration errors may
occur if the cluster is connected electrically to
another vehicle; or, if an electronic module
from

another

vehicle

connected

that

provides

data

the

instrument

cluster

(including odometer values) that conflicts with
that which was previously learned and stored.

Therefore,

the

practice

exchanging

(swapping) instrument clusters and other
electronic modules in this vehicle with those
removed from another vehicle must always
be avoided. Failure to observe this caution
may result in instrument cluster damage,
which is not reimbursable under the terms of

the product warranty. Service replacement
instrument clusters are provided with the
correct VIN, and the certified odometer and
engine hours values embedded in cluster
memory, but will otherwise be automatically
configured for compatibility with the features
and optional equipment in the vehicle in
which they are initially installed.

GENERAL INFORMATION

For complete Description and Operation of the

Instrument Cluster, refer to the DR Service Manual
Instrument Cluster Section. For information re-
garding systems such as Wiper/Washer, RKE,
Lighting, etc., refer to those section titles in this
publication and the DR Service Manual.

3.10.1

DIAGNOSTIC SELF TEST

The Instrument Cluster is capable of performing

a Diagnostic Self Test. This self test can be initiated
manually by depressing and holding the trip reset
button while cycling the ignition from the Off to the
On position. The self test can also be activated
using the DRBIII

t. During the self test, all of the

PCI bus indicators will be illuminated. The speed-
ometer, tachometer, fuel gauge, oil pressure gauge,
coolant temperature gauge, and voltage gauge will
position at their calibration points. The VF display
will illuminate all segments and also display the
software version. The chime will sound. When the
self test is complete, the cluster will return to
normal operation. Turning the ignition to the Off
position or the cluster detecting engine RPM
greater than 0 (zero) will stop the self test.

3.11

INTERIOR LIGHTING

The Instrument Cluster controls the Interior/

Courtesy Lamps. The Instrument Cluster activates
the courtesy lamps when either a Dome Lamp
switch is turned on or a door is opened. The Instru-
ment Cluster also monitors the output of the Glove
Box and Map lamps. The Cargo lamps are con-
trolled by the Instrument Cluster, it receives an
output message from the Headlamp switch to turn
on the lamps. The Instrument Cluster provides
battery protection by shutting down the interior
lamps when a door or courtesy/map lamp is left on
or open.

3.12

POWER DOOR LOCKS/REMOTE
KEYLESS ENTRY

The Instrument Cluster in response to the door

lock switches or the RKE module directly controls
the power door lock motors. The Instrument Cluster
monitors the activation of the door lock motors and
will set diagnostic trouble codes when there is an
open or short condition. When there is a lock or
unlock input from a switch or RKE command, the
Instrument Cluster will activate the appropriate
driver for 300 milliseconds. If a lock or unlock
switch remains active, the request will be ignored
until the switch transitions back to off. The lock
switches are resistive multiplexed input devices
hardwired to the Instrument Cluster.

3.12.1

AUTOMATIC DOOR LOCKS

The Instrument Cluster will automatically lock

all the doors when the vehicle speed exceeds 15
MPH (24 KMH), throttle position exceeds 10 per-
cent and all the doors are closed. If a door is opened
the Automatic Door Lock feature shall reset and the
Instrument Cluster will lock the doors when the
above conditions are met. This feature is program-
mable by the customer or the DRBIII

3.12.2

CENTRAL LOCKING/UNLOCKING

The Instrument Cluster will lock all doors when

the cylinder lock switch is activated in the

9lock9

position. When the Instrument Cluster receives an
unlock command from the driver cylinder lock
switch, it will unlock only that door. If the Instru-
ment Cluster receives a second command within a
5-second period it will unlock all the remaining
doors. The illuminated entry will activate during
door unlock.

3.12.3

DOOR LOCK INHIBIT

When the key is in the ignition, in any position,

and either front door is open, the door lock switches
LOCK functions are disabled. The UNLOCK func-
tions are still functional. This protects against
locking the vehicle with the keys still in the igni-
tion. The RKE transmitter will still lock the doors
as usual.

3.12.4

ENHANCED ACCIDENT RESPONSE

Upon detection of an airbag deployment by way of

the PCI bus, the Instrument Cluster shall:

•

Immediately disable the power door lock output

•

Unlock all doors by activating the door unlock
output for approximately 300 milliseconds.

•

After actuating the door unlock output, allow the
door lock motors to be activated if the door lock
input has been inactive (not erratic) for 2 seconds
since the reception of the airbag deployment
message.

3.13

REMOTE KEYLESS ENTRY

The remote keyless entry (RKE) feature is used to

control the power door locks and panic feature by
using a remote transmitter (keyfob) and receiver
located within the instrument cluster. The instru-
ment cluster RKE feature controls the driver door
unlock, all doors lock/unlock, horn chirp enabled/
disable, optical chirp enabled/disable, illuminated
entry, the panic feature, initiate customer program-
ming, and arming/disarming the Vehicle Theft Se-
curity System.

When a valid lock message is received from the

receiver, the instrument cluster will:

GENERAL INFORMATION

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