2002 CHRYSLER CARAVAN diagram

NOTE: Use care when inserting CD changer so that
cable is not pinched or trapped against instrument
panel.
(3) Install screws holding CD changer.
(4) Reconnect the battery negative cable.
INSTRUMENT PANEL
ANTENNA CABLE
REMOVAL
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.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove glove box (Refer to 23 - BODY/IN-
STRUMENT PANEL/GLOVE BOX - REMOVAL).
(3) Disconnect extension cable end from antenna
cable end.
(4) Disconnect cable hanger clip from HVAC unit.
(5) Remove radio as necessary to gain access to
extension cable (Refer to 8 - ELECTRICAL/AUDIO/
RADIO - REMOVAL).
(6) Disconnect extension cable from back of radio.
(7) Remove extension cable from vehicle.
INSTALLATION
(1) Install extension cable to vehicle.
(2) Connect extension cable to back of radio.
(3) Install radio (Refer to 8 - ELECTRICAL/AU-
DIO/RADIO - INSTALLATION).
(4) Connect cable hanger clip to HVAC unit.
(5) Connect extension cable end to antenna cable
end.
(6) Install glove box (Refer to 23 - BODY/INSTRU-
MENT PANEL/GLOVE BOX - INSTALLATION).
(7) Connect the battery negative cable.
QUARTER GLASS INTEGRAL
ANTENNA - EXPORT
DESCRIPTION
The quarter glass integral antenna element is
bonded to the right rear quarter glass and is replaced
with the glass assembly only (Fig. 7).
OPERATION
The integral antenna receives RF (Radio Frequen-
cies) and sends them to the antenna module for
amplification.
DIAGNOSIS AND TESTING - QUARTER GLASS
INTEGRAL ANTENNA - EXPORT
The antenna grid pattern is divided into two sepa-
rate patterns. Each terminal connects to a separate
grid pattern, one for AM and the other for FM.
For circuit descriptions and diagrams, refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds. To detect breaks in the
integral antenna elements, the following procedure is
required:
(1) Disconnect the antenna module connector from
the antenna terminals on the glass.
(2) Using an ohmmeter, place a lead on one of the
terminals and check each end of the grid pattern con-
nected to this terminal for continuity. If continuity is
not present, move one lead through the grid in pro-
gression starting at the terminal with the other lead
on the terminal until continuity is lost. Repeat pro-
cedure for the other terminal. A break in the antenna
grid can be repaired using a Mopar Rear Window
Defogger Repair Kit (Part Number 4267922) or
equivalent. (Refer to 8 - ELECTRICAL/HEATED
GLASS/WINDSHIELD GRID - STANDARD PROCE-
DURE).
Fig. 7 QUARTER GLASS INTEGRAL ANTENNA
1 - REAR QUARTER GLASS
2 - ANTENNA
8A - 8 AUDIORS
CD CHANGER (Continued)
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RADIO
DIAGNOSIS AND TESTING - RADIO
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.
Any diagnosis of the Audio system should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the DRB
IIIt, refer to the appropriate Diagnostic Service
Manual.
Refer to the appropriate 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 connectors, splices and grounds.
If the vehicle is equipped with remote radio
switches located on the back of the steering wheel
spokes, and the problem being diagnosed is related to
one of the symptoms listed below, be certain to check
the remote radio switches and circuits as described
in this group, prior to attempting radio diagnosis or
repair.
²Stations changing with no remote radio switch
input
²Radio memory presets not working properly
²Volume changes with no remote radio switch
input
²Remote radio switch buttons taking on other
functions
²CD player skipping tracks
²Remote radio switch inoperative.
CAUTION: The speaker output of the radio is a
ªfloating groundº system. Do not allow any speaker
lead to short to ground, as damage to the radio
may result.
(1) Check the fuse(s) in the junction block and the
Integrated Power Module (IPM). If OK, go to Step 2.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse(s).
(2) Check for battery voltage at the fuse in the
(IPM). If OK, go to Step 3. If not OK, repair the open
circuit to the battery as required.
(3) Turn the ignition switch to the ON position.
Check for battery voltage at the fuse in the junction
block. If OK, go to Step 4. If not OK, repair the open
circuit to the ignition switch as required.(4) Turn the ignition switch to the OFF position.
Remove the radio, but do not unplug the wire har-
ness connectors. Check for continuity between the
radio chassis and a good ground. There should be
continuity. If OK, go to Step 5. If not OK, repair the
open radio chassis ground circuit as required.
(5) Connect the battery negative cable. Turn the
ignition switch to the ON position. Check for battery
voltage at the fused ignition switch output circuit
cavity of the radio wire harness connector. If OK, go
to Step 6. If not OK, repair the open circuit as
required.
(6) Turn the ignition switch to the OFF position.
Check for battery voltage at the fused B(+) circuit
cavity of the radio wire harness connector. If OK,
replace the faulty radio. If not OK, repair the open
circuit to the Ignition-Off Draw (IOD) fuse as
required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove cup holder.
(3) Remove trim panel above cupholder by pulling
straight out.
(4) Remove center instrument panel trim panel.
(5) Remove screws holding radio to instrument
panel.
(6) Pull radio rearward to gain access to the back
of radio (Fig. 8).
(7) Disconnect the antenna cable by pulling the
locking antenna connector away from the radio (Fig.
9).
(8) Disconnect bolt holding ground strap to the
radio (if equipped).
Fig. 8 RADIO
1 - RADIO
2 - CD-PLAYER
RSAUDIO8A-9
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REMOTE SWITCHES
DESCRIPTION
A remote radio control switch option is available on
some models. Two rocker-type switches are mounted
on the back (instrument panel side) of the steering
wheel spokes (Fig. 10). The switch on the left spoke
is the seek switch and has seek up, seek down, and
preset station advance functions. The switch on the
right spoke is the volume control switch and has vol-
ume up, and volume down functions. The switch on
the right spoke also includes a ªmodeº control that
allows the driver to sequentially select AM radio, FM
radio, cassette player, CD player or CD changer (if
equipped).
OPERATION
These switches are resistor multiplexed units that
are hard-wired to the Body Control Module (BCM)
through the clockspring. The BCM sends the proper
messages on the Programmable Communications
Interface (PCI) data bus network to the radio
receiver. For diagnosis of the BCM or the PCI data
bus, the use of a DRB IIItscan tool and the proper
Diagnostic Procedures manual are recommended. For
more information on the operation of the remote
radio switch controls, refer to the owner's manual in
the vehicle glove box.
DIAGNOSIS AND TESTING - REMOTE
SWITCHES
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.
Any diagnosis of the Audio system should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the DRB
IIIt, refer to the appropriate Diagnostic Service
Manual.
Refer to the appropriate 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 connectors, splices and grounds.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the airbag system capac-
itor to discharge before further service.
(2) Remove the remote radio switch(es) from the
steering wheel. (Refer to 8 - ELECTRICAL/AUDIO/
REMOTE SWITCHES - REMOVAL).
(3) Use an ohmmeter to check the switch resis-
tance as shown in the Remote Radio Switch Test
table (Fig. 11).
Fig. 10 Remote Radio Switch Operational View
1 - PRESET SEEK
2 - SEEK UP
3 - VOLUME UP
4 - MODE
5 - VOLUME DOWN
6 - SEEK DOWN
Fig. 11 Remote Radio Switches
1 - WHITE REAR SWITCH
2 - BLACK REAR SWITCH
RSAUDIO8A-11
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Any diagnosis of the Audio system should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the DRB
IIIt, refer to the appropriate Diagnostic Service
Manual.
Refer to the appropriate 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 connectors, splices and grounds.
CAUTION: The speaker output of the radio is a
ªfloating groundº system. Do not allow any speaker
lead to short to ground, as damage to the radio
may result.
(1) If all speakers are inoperative, check the radio
fuses in the junction block. If OK, go to Step 2. If not
OK, repair the shorted circuit or component as
required and replace the faulty fuse.
(2) Turn the ignition switch to the ON position.
Turn the radio receiver ON. Adjust the balance and
fader control controls to check the performance of
each individual speaker. Note the speaker locations
that are not performing correctly. Go to Step 3.
(3) Turn the radio receiver OFF. Turn the ignition
OFF. Disconnect and isolate the battery negative
cable. Remove the radio receiver.
(4) Check both the speaker feed (+) circuit and
return (-) circuit cavities for the inoperative speaker
at the radio receiver wire harness connector for con-
tinuity to ground. There should be no continuity. If
OK, go to Step 5. If not OK, repair the shorted
speaker feed (+) and/or return (-) circuits(s) to the
speaker as required.
(5) Disconnect wire harness connector at the inop-
erative speaker. Check for continuity between the
speaker feed (+) circuit cavities of the radio receiver
wire harness connector. Repeat the check between
the speaker return (-) circuit cavities of the radio
receiver wire harness connector and the speaker wire
harness connector. In each case, there should be con-
tinuity. If OK, replace the faulty speaker. If not OK,
repair the open speaker feed (+) and/or return (-) cir-
cuits(s) as required.
REMOVAL
D-PILLAR SPEAKER
(1)Disconnect and isolate the battery negative cable.
(2) Remove rear header trim (right side speaker).
(3) Remove jack cover (left side speaker).
(4) Remove liftgate scuff plate.
(5) Remove upper seat belt bolt. (Refer to 8 -
ELECTRICAL/RESTRAINTS/SEAT BELT OUT-
BOARD FRONT - REMOVAL).(6) Partially remove quarter trim panel to access
the D-pillar speaker.
(7) Slide the speaker from the retainer (Fig. 12).
(8) Disconnect the wire harness connector from the
speaker.
FRONT DOOR SPEAKER
(1)Disconnect and isolate the battery negative cable.
(2)Remove the front door trim panel. (Refer to 23 -
BODY/DOOR - FRONT/TRIM PANEL - REMOVAL).
(3) Remove the speaker mounting screws (Fig. 13).
(4) Disconnect wire harness connector and remove
speaker from door.
Fig. 12 D-PILLAR SPEAKER
1 - SPEAKER
2 - RETAINER
3 - TRIM PANEL
Fig. 13 DOOR SPEAKER
1 - SPEAKER
2 - WIRE HARNESS CONNECTOR
RSAUDIO8A-13
SPEAKER (Continued)
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(a) BCM has two battery feeds at pin 1 and pin
5 of the 6±way connector.
(b) Pin 5 of the (BX2) 32 way connector of the
BCM for ignition feed.
(c) Check voltage (PX2) connector, pin 34 for 12v.
(d) If voltage OK, go to step Step 3
(e) If NO voltage repair as necessary. Refer to
the appropriate wiring information. The wiring
information includes wiring 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.
(3) Check driver's seat belt buckle switch input
(form ORC) for a closed circuit when not buckled. If
input not seen, look for open in wiring or switch. The
switch is grounded when belt is not buckled.
(4) Verify PCI data bus communication between
ORC and BCM.
NO FASTEN SEAT BELT LAMP WHEN IGNITION
SWITCH IS TURNED ON.
(1) Check for burned out lamp.
(2) Using a voltmeter check for voltage at the clus-
ter conncctor:
(a) Pin 2 of the mechanical instrument cluster
for battery feed.
(b) Pin 11 of the mechanical instrument cluster
for ignition voltage.
(3) Repair as necessary.
FASTEN SEAT BELT LAMP OR TONE CONTINUES
FOR MORE THAN 10 SECONDS AFTER SEAT
BELTS ARE FASTENED AND DRIVER'S DOOR IS
CLOSED.
Refer to the proper Body Diagnostic Procedures
manual.
NO TONE WHEN PARK OR HEADLAMPS ARE ON
AND DRIVER'S DOOR IS OPEN.
Make sure ignition is in lock position with the key
removed.
(1) Check the BCM DTC's and BCM sensors to
verify the door is open. Repair as necessary.
(2) Actuate Chime (BCM actuates).
(3) Inspect BCM connectors and wires for proper
connection.
(4) Measure with a voltmeter the voltage (12v) on
BCM connector (PX2) pin 34 with harness connected.
DIAGNOSIS AND TESTING - DOME LAMP ON
CHIME
The dome lamp on chime will warn the driver that
the dome lamps have been left on.When the ignition is OFF and the key is out of the
ignition:
²Driver's door OPEN (door ajar switch is closed to
ground) and
²Dome lamps are ON (dome lamp switch is closed
to ground),
The chime will sound continuously until the driv-
ers door is closed, dome lamps turned OFF or until
the battery protection time out of 15 minutes has
expired. Chime rate: 168 to 192 chimes per minute.
DIAGNOSIS AND TESTING - ENGINE
TEMPERATURE CRITICAL CHIME
The engine temperature critical chime will warn
the driver that the vehicle's engine is overheating.
While monitoring the coolant temperature, the Pow-
ertrain Control Module (PCM) will send on the PCI
data bus as engine temperature every 1.376 seconds
to the cluster. The MIC calculates engine tempera-
ture and determines if a warning should occur. This
feature is functional only with the Ignition Switch in
the Run/Start position.
When the engine temperature reaches 122ÉC
(252ÉF) the MIC requests a chime from the BCM and
the engine temperature lamp comes ON. The MIC
turns OFF the lamp when the engine temperature
reaches 117ÉC (242ÉF). The MIC will chime continu-
ously (request from the BCM). The chime will turn
OFF after four minutes or when the temperature
reaches 117ÉC (242ÉF), which ever occurs first.
DIAGNOSIS AND TESTING - EXTERIOR LAMPS
ON CHIME
The exterior lamp on chime will warn the driver
that the exterior lights have been left on.
With the ignition switch OFF/key out of ignition:
²Driver's door is open (door ajar switch is closed
to ground)
²Parking lamps or headlamps ON (parking lamp
switch is closed to ground)
The chime will sound until lights are turned OFF,
driver's door closed or until the battery protection
time out of 3 minutes has expired.
Chime rate: 168 to 192 chimes per minute.
To test the exterior lamps left on function:
²Turn ignition off
²Remove ignition key
²Turn exterior lamps on with driver's door open.
Chime should sound until lamps are turned off or
driver's door is closed.
DIAGNOSIS AND TESTING - KEY-IN IGNITION
CHIME
The key-in ignition chime will act as a warning to
the driver that the ignition key has been left in the
8B - 2 CHIME/BUZZERRS
CHIME/BUZZER (Continued)
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seat switch. Refer toDiagnosis and Testing
Heated Seat Switchin Heated Seats for heated
seat switch diagnosis and testing procedures. If the
heated seat switch checks OK, proceed as follows.
(1) Check the heated seat element (Refer to 8 -
ELECTRICAL/HEATED SEATS/HEATED SEAT
ELEMENT - DIAGNOSIS AND TESTING).
(2) Check the heated seat sensor (Refer to 8 -
ELECTRICAL/HEATED SEATS/HEATED SEAT
SENSOR - DIAGNOSIS AND TESTING).
(3) Check the heated seat switch (Refer to 8 -
ELECTRICAL/HEATED SEATS/DRIVER HEATED
SEAT SWITCH - DIAGNOSIS AND TESTING).
NOTE: Refer to Wiring for the location of complete
heated seat system wiring diagrams and connector
pin-out information.
(4) Using a voltmeter, backprobe the appropriate
heated seat module connector, do not disconnect.
Check for voltage at the appropriate pin cavities. 12v
should be present. If OK go to Step 5, if Not, Repair
the open or shorted voltage supply circuit as
required.
(5) Using a ohmmeter, backprobe the appropriate
heated seat module connector, do not disconnect.
Check for proper continuity to ground on the ground
pin cavities. Continuity should be present. If OK
replace the heated seat module with a known good
unit and retest system, if Not OK, Repair the open or
shorted ground circuit as required.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the appropriate front seat from the
vehicle (Refer to 23 - BODY/SEATS/SEAT - REMOV-
AL).
(3) Unsnap the module from the seat cushion pan.
(4) Disconnect the module wire harness connec-
tors.
INSTALLATION
(1) Connect the module wire harness connectors.
(2) Snap the module on the seat cushion pan.
(3) Install the appropriate front seat in the vehicle
(Refer to 23 - BODY/SEATS/SEAT - INSTALLA-
TION).
(4) Connect and isolate the negative battery cable.
POWER LIFTGATE MODULE
DESCRIPTION
Vehicles equipped with a power liftgate (PLG) uti-
lize a PLG control module. This module is located on
the vehicles left side D-pillar just below the motorassembly (Fig. 9) and contains a microprocessor,
which is used to communicate to the vehicles body
control module. The PLG control module receives and
monitors logic inputs from all the PLG system
switches except for the outside handle switch. This
module also contains the software technology to
detect liftgate obstructions and stop and / or reverse
the door accordingly.
OPERATION
The PLG control module contains the electronic cir-
cuitry and software used to control the sequence of
events for the PLG system. This module comunicates
on the PCI bus circuit with the vehicles body control
module to monitor many different inputs and outputs
such as door lock status, transmission gear selector
position and vehicle speed. Refer to PLG system
operation for more information.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove left D-pillar trim panel from the vehi-
cle. Refer to Body for the procedure.
(3) Disconnect the wire harness connections from
the PLG motor assembly (Fig. 10).
Fig. 9 LIFTGATE CONTROL MODULE
1 - POWER LIFTGATE CONTROL MODULE
2 - MODULE RETAINING SCREWS
3 - D-PILLAR
4 - POWER LIFTGATE MOTOR
5 - MODULE ELECTRICAL CONNECTORS
8E - 10 ELECTRONIC CONTROL MODULESRS
HEATED SEAT MODULE (Continued)
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MEMORY SEAT/MIRROR
MODULE
DESCRIPTION
Vehicles equipped with the memory seat/mirror
option, utilize a memory module located under the
drivers front seat. This module is basically wired in-
line between the power seat switch and the power
seat track/adjuster motors, or in-line between the
power mirror switch and the power side view mir-
ror(s) motor(s). The MSMM contains a central pro-
cessing unit that communicates with other modules
on the Programmable Communications Interface
(PCI) data bus network.
The Memory Seat/Mirror Module (MSMM) receives
hard wired inputs from the driver power seat switch
and the potentiometers on each of the driver side
power seat track motors, or from the power mirror
switch and the potentiometers on the side view mir-
ror. The MSMM receives messages over the PCI data
bus from the Body Control Module (BCM) (memory
switch status), the Powertrain Control Module (PCM)
(vehicle speed status). The MSMM will prevent the
seat memory recall function from being initiated if
the driver side seat belt is buckled, if the transmis-
sion gear selector lever is not in the Park or Neutral
positions, or if the vehicle is moving.
For diagnosis of the MSMM or the PCI data bus, a
DRB IIItscan tool and the proper Diagnostic Proce-
dures manual are recommended. The MSMM cannot
be repaired and, if faulty or damaged, it must be
replaced. Refer toMemory Systemin the Power
Seat or Power Mirror section of this manual for more
information on the memory system option.
OPERATION
When memory system operation is requested
(depressing of the memory switch), a resistor multi-
plexed signal is sent from the memory switch to the
body control module (BCM). The body control module
will then send the appropriate signals out to the
memory/mirror seat module, the memory/mirror seat
module then applies the voltage supply to the power
seat track or side-view mirror if the proper require-
ments are met. The vehicle speed must equal zero
and the transmission must be in park or neutral in
order for the memory system to function.
DIAGNOSIS AND TESTING - MEMORY
SEAT/MIRROR MODULE
Visually inspect the related wiring harness connec-
tors. Look for broken, bent, pushed out, or corroded
terminals. If any of the above conditions are present,
repair as necessary. If not, use a DRB IIItscan tool
and the proper Diagnostic Procedures Manual to testthe memory/mirror seat module. For complete circuit
diagrams, refer toWiring Diagrams.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the driver side front bucket seat
retaining nuts from under the vehicle (Refer to 23 -
BODY/SEATS/SEAT - REMOVAL).
(3) Lift the drivers seat up and out of the mount-
ing holes in the floor pan and lay the seat rearward
to access the module located under the seat. It is not
necessary to disconnect the seat electrical, just use
care not to damage the wiring by over-extending.
(4) Disconnect the memory/mirror seat module
electrical connectors. Depress the retaining tab and
pull straight apart.
(5) Remove the module retaining bolts and remove
the module from the bracket.
INSTALLATION
(1) Position and install the module retaining bolts.
(2) Connect the memory/mirror seat module elec-
trical connectors.
(3) Position the drivers seat in the mounting holes
in the floor pan.
(4) Install the driver side front bucket seat retain-
ing nuts from under the vehicle (Refer to 23 - BODY/
SEATS/SEAT - INSTALLATION).
(5) Connect the battery negative cable.
SLIDING DOOR CONTROL
MODULE
DESCRIPTION
Vehicles equipped with a power sliding door utilize
a sliding door control module. The sliding door con-
trol module is located behind the sliding door trim
panel in the center of the door, just above the sliding
door motor (Fig. 20). This module controls the opera-
tion of the door through the Programmable Commu-
nication Interface (PCI) J1850 data bus circuit and
the Body Control Module. The sliding door control
module contains software technology which enables it
to detect resistance to door travel and to reverse door
travel in order to avoid damage to the door or to
avoid possible personal injury if the obstruction is a
person. This feature functions in both the opening
and closing cycles. If the power sliding door system
develops any problems the control module will store
and recall Diagnostic Trouble Codes (DTC). The use
of a diagnostic scan tool, such as the DRB IIItis
required to read and troubleshoot these trouble
codes. The sliding door control module can be
RSELECTRONIC CONTROL MODULES8E-33
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these sensor inputs to adjust fuel quantity and fuel
injector timing.
Limp-In Mode
If there is a fault detected with the accelerator
pedal position sensor, the ECM will set the engine
speed at 1100 RPM.
Overspeed Detection Mode
If the ECM detects engine RPM that exceeds 5200
RPM, the ECM will set a DTC in memory and illu-
minate the MIL until the DTC is cleared.
After-Run Mode
The ECM transfers RAM information to ROM and
performs an Input/Output state check.
MONITORED CIRCUITS
The ECM is able to monitor and identify most
driveability related trouble conditions. Some circuits
are directly monitored through ECM feedback cir-
cuitry. In addition, the ECM monitors the voltage
state of some circuits and compares those states with
expected values. Other systems are monitored indi-
rectly when the ECM conducts a rationality test to
identify problems. Although most subsytems of the
engine control module are either directly or indirectly
monitored, there may be occasions when diagnostic
trouble codes are not immediately identified. For a
trouble code to set, a specific set of conditions must
occur and unless these conditions occur, a DTC will
not set.
DIAGNOSTIC TROUBLE CODES
Each diagnostic trouble code (DTC) is diagnosed by
following a specific procedure. The diagnostic test
procedure contains step-by-step instruction for deter-
mining the cause of the DTC as well as no trouble
code problems. Refer to the appropriate Diesel Pow-
ertrain Diagnostic Manual for more information.
HARD CODE
A DTC that comes back within one cycle of the
ignition key is a hard code. This means that the
problem is current every time the ECM/SKIM checks
that circuit or function. Procedures in this manual
verify if the DTC is a hard code at the beginning of
each test. When the fault is not a hard code, an
intermittent test must be performed. NOTE: If the
DRBIIItdisplays faults for multiple components (i.e.
ECT, VSS, IAT sensors) identify and check the
shared circuits for possible problems before continu-
ing (i.e. sensor grounds or 5-volt supply circuits).
Refer to the appropriate schematic to identify shared
circuits. Refer to the appropriate Diesel Powertrain
Diagnostic Manual for more information.INTERMITTENT CODE
A DTC that is not current every time the ECM/
SKIM checks the circuit or function is an intermit-
tent code. Most intermittent DTCs are caused by
wiring or connector problems. Problems that come
and go like this are the most difficult to diagnose;
they must be looked for under specific conditions that
cause them.NOTE: Electromagnetic (radio)
interference can cause an intermittent system
malfunction.This interference can interrupt com-
munication between the ignition key transponder and
the SKIM. The following checks may assist you in
identifying a possible intermittent problem:
²Visually inspect the related wire harness connec-
tors. Look for broken, bent, pushed out or corroded
terminals.
²Visually inspect the related wire harness. Look
for chafed, pierced or partially broken wire.
²Refer to hotlines or technical service bulletins
that may apply. Refer to the appropriate Diesel Pow-
ertrain Diagnostic Manual for more information.
ECM DIAGNOSTIC TROUBLE CODES
IMPORTANT NOTE: Before replacing the ECM for
a failed driver, control circuit or ground circuit, be
sure to check the related component/circuit integrity
for failures not detected due to a double fault in the
circuit. Most ECM driver/control circuit failures are
caused by internal failures to components (i.e. relays
and solenoids) and shorted circuits (i.e. sensor pull-
ups, drivers and ground circuits). These faults are
difficult to detect when a double fault has occurred
and only one DTC has set. If the DRBIIItdisplays
faults for multiple components (i.e.VSS, ECT, Batt
Temp, etc.) identify and check the shared circuits for
possible problems before continuing (i.e. sensor
grounds or 5-volt supply circuits). Refer to the appro-
priate wiring diagrams to identify shared circuits.
Refer to the appropriate Diesel Powertrain Diagnos-
tic Manual for more information.
STANDARD PROCEDURE - PCM/ECM/SKIM
PROGRAMMING - DIESEL
NOTE: Before replacing the PCM/ECM for a failed
driver, control circuit or ground circuit, be sure to
check the related component/circuit integrity for
failures not detected due to a double fault in the cir-
cuit. Most PCM/ECM driver/control circuit failures
are caused by internal component failures (i.e. relay
and solenoids) and shorted circuits (i.e. pull-ups,
drivers and switched circuits). These failures are
difficult to detect when a double fault has occurred
and only one DTC has set.
8Ea - 2 ELECTRONIC CONTROL MODULESRG
ENGINE CONTROL MODULE (Continued)
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