ELECTRONIC CONTROL MODULES
TABLE OF CONTENTS
page page
ENGINE CONTROL MODULE
DESCRIPTION..........................1
OPERATION............................1
STANDARD PROCEDURE - PCM/ECM/SKIM
PROGRAMMING - DIESEL...............2REMOVAL.............................4
INSTALLATION..........................4
ENGINE CONTROL MODULE
DESCRIPTION
The ECM is located in the left front corner of the
engine compartment attached to the radiator support
(Fig. 1).
OPERATION
The ECM has been programmed to monitor differ-
ent circuits of the diesel fuel injection system. Thismonitoring is called on-board diagnostics. Certain cri-
teria must be met for a diagnostic trouble code to be
entered into the ECM memory. The criteria may be a
range of: engine rpm, engine temperature, time or
other input signals to the ECM. If all of the criteria
for monitoring a system or circuit are met, and a
problem is sensed, then a DTC will be stored in the
ECM memory. It is possible that a DTC for a moni-
tored circuit may not be entered into the ECM mem-
ory, even though a malfunction has occurred. This
may happen when the monitoring criteria have not
been met. The ECM compares input signal voltages
from each input device with specifications (the estab-
lished high and low limits of the input range) that
are programmed into it for that device. If the input
voltage is not within the specifications and other
trouble code criteria are met, a DTC will be stored in
the ECM memory.
ECM OPERATING MODES
As input signals to the ECM change, the ECM
adjusts its response to the output devices. For exam-
ple, the ECM must calculate a different fuel quantity
and fuel timing for engine idle condition than it
would for a wide open throttle condition. There are
several different modes of operation that determine
how the ECM responds to the various input signals.
Ignition Switch On (Engine Off)
When the ignition is turned on, the ECM activates
the glow plug relay for a time period that is deter-
mined by engine coolant temperature, atmospheric
temperature and battery voltage.
Engine Start-Up Mode
The ECM uses the engine temperature sensor and
the crankshaft position sensor (engine speed) inputs
to determine fuel injection quantity.
Normal Driving Modes
Engine idle, warm-up, acceleration, deceleration
and wide open throttle modes are controlled based on
all of the sensor inputs to the ECM. The ECM uses
Fig. 1 ENGINE CONTROL MODULE LOCATION-
TYPICAL
1 - BATTERY
2 - IPM (INTEGRATED POWER MODULE)
3 - ECM (ENGINE CONTROL MODULE)
4 - RETAINING BOLT
5 - RADIATOR SUPPORT
6 - CLUTCH CABLE BRACKET (LHD)
7 - CLUTCH CABLE BRACKET RETAINING BOLT (LHD)
RGELECTRONIC CONTROL MODULES8Ea-1
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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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PCM/SKIM PROGRAMMING
When a PCM (JTEC) and the SKIM are replaced
at the same time perform the following steps in
order:
(1) Program the new PCM (JTEC)
(2) Program the new SKIM
(3) Replace all ignition keys and program them to
the new SKIM.
ECM/SKIM PROGRAMMING
When an ECM (Bosch) and the SKIM are replaced
at the same time perform the following steps in
order:
(1) Program the new SKIM
(2) Program the new ECM (Bosch)
PROGRAMMING THE ECM (Bosch)
(1) To program the VIN, connect the DRB III and
turn the ignition on.
(2) Select Engine from the main menu. The DRB
III will require the VIN to be entered before continu-
ing.
(3) Select ENTER to update the VIN. The DRB III
will display the updated VIN.
(4) If the engine is equipped with air conditioning,
the ECM A/C function must be enabled. Enable the
ECM A/C function as follows:
²Using the DRB III select ENGINE, MISCELLA-
NEOUS, then ENABLE/DISABLE A/C
²Push 1 to enable A/C. DRB III screen should dis-
play A/C Activated.
PROGRAMMING THE PCM (JTEC)
The SKIS Secret Key is an ID code that is unique
to each SKIM. This code is programmed and stored
in the SKIM, PCM and transponder chip (ignition
keys). When replacing the PCM it is necessary to
program the secret key into the new PCM using the
DRB III. Perform the following steps to program the
secret key into the PCM.
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRB III and select THEFT ALARM,
SKIM then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
(5) Select ENTER to update PCM VIN.
NOTE: If three attempts are made to enter secure
access mode using an incorrect PIN, secured
access mode will be locked out for one hour. To
exit this lockout mode, turn the ignition to the RUN
position for one hour then enter the correct PIN.
(Ensure all accessories are turned off. Also monitorthe battery state and connect a battery charger if
necessary).
(6) Press ENTER to transfer the secret key (the
SKIM will send the secret key to the PCM).
(7) Press Page Back to get to the Select System
menu and select ENGINE, JTEC (diesel only), MIS-
CELLANEOUS, and SRI MEMORY CHECK.
(8) The DRB III will ask, Is odometer reading
between XX and XX? Select the YES or NO button on
the DRB III. If NO is selected, the DRB III will read,
Enter odometer Reading
the odometer reading from the Instrument Panel and
press ENTER.
PROGRAMMING THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRB III and select THEFT ALARM,
SKIM then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE).
(4) Program the vehicle four-digit PIN into SKIM.
(5) Select COUNTRY CODE and enter the correct
country.
NOTE: Be sure to enter the correct country code. If
the incorrect country code is programmed into
SKIM, the SKIM must be replaced.
(6) Select YES to update VIN (the SKIM will learn
the VIN from the PCM).
(7) Press ENTER to transfer the secret key (the
PCM will send the secret key to the SKIM).
(8) Program ignition keys to SKIM.
NOTE: If the PCM and the SKIM are replaced at the
same time, all vehicle keys will need to be replaced
and programmed to the new SKIM.
PROGRAMMING IGNITION KEYS TO THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRB III and select THEFT ALARM,
SKIM then MISCELLANEOUS.
(3) Select PROGRAM IGNITION KEY'S.
(4) Enter secured access mode by entering the
vehicle four-digit PIN.
NOTE: A maximum of eight keys can be learned to
each SKIM. Once a key is learned to a SKIM it (the
key) cannot be transferred to another vehicle.
If ignition key programming is unsuccessful, the
DRB III will display one of the following messages:
Programming Not Attempted - The DRB III
attempts to read the programmed key status and
there are no keys programmed into SKIM memory.
RGELECTRONIC CONTROL MODULES8Ea-3
ENGINE CONTROL MODULE (Continued)
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Programming Key Failed (Possible Used Key From
Wrong Vehicle) - SKIM is unable to program key due
to one of the following:
²faulty ignition key transponder
²ignition key is programmed to another vehicle.
8 Keys Already Learned, Programming Not Done -
SKIM transponder ID memory is full.
(5) Obtain ignition keys to be programmed from
customer (8 keys maximum).
(6) Using the DRB III, erase all ignition keys by
selecting MISCELLANEOUS and ERASE ALL CUR-
RENT IGN. KEYS.
(7) Program all ignition keys.
Learned Key In Ignition - Ignition key transponder
ID is currently programmed in SKIM memory.
REMOVAL
(1) Disconnect negative battery cable.
(2) Remove left front headlamp module (Refer to 8
- ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
HEADLAMP UNIT - REMOVAL).
(3) Remove lower headlamp assembly mounting
bolt (Fig. 2).(4) Remove ECM upper mounting bolts (Fig. 3).
(5) Lift ECM from radiator support.
(6) Disconnect ECM electrical connectors.
(7) Separate ECM from mounting bracket.
INSTALLATION
(1) Install ECM on mounting bracket.
(2) Connect ECM electrical connectors.
(3) Place ECM and bracket assembly in position on
radiator support.
(4) Install upper and lower mounting bolts.
(5) Install left headlamp module (Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
HEADLAMP UNIT - INSTALLATION).
(6) Connect negative battery cable.
(7) Program ECM as necessary (Refer to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/EN-
GINE CONTROL MODULE - STANDARD
PROCEDURE).
Fig. 2 ENGINE CONTROL MODULE-LOWER
MOUNTING BOLT
1 - ENGINE CONTROL MODULE (ECM)
2 - INTEGRATED POWER MODULE
3 - ECM LOWER MOUNTING BOLT
Fig. 3 ENGINE CONTROL MODULE-UPPER
MOUNTING BOLTS
1 - BATTERY
2 - INTEGRATED POWER MODULE
3 - ENGINE CONTROL MODULE
4 - RADIATOR SUPPORT
5 - ECM UPPER MOUNTING BOLTS
6 - ECM ELECTRICAL CONNECTORS
8Ea - 4 ELECTRONIC CONTROL MODULESRG
ENGINE CONTROL MODULE (Continued)
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ENGINE SYSTEMS
TABLE OF CONTENTS
page page
BATTERY SYSTEM......................... 1
CHARGING.............................. 21STARTING............................... 28
BATTERY SYSTEM
TABLE OF CONTENTS
page page
BATTERY SYSTEM
DESCRIPTION..........................1
OPERATION............................2
DIAGNOSIS AND TESTING - BATTERY
SYSTEM.............................2
CLEANING.............................5
INSPECTION...........................5
SPECIFICATIONS........................6
SPECIAL TOOLS
BATTERY SYSTEM SPECIAL TOOLS.......7
BATTERY
DESCRIPTION..........................7
OPERATION............................9
DIAGNOSIS AND TESTING - BATTERY.......9
STANDARD PROCEDURE
STANDARD PROCEDURE - SPIRAL PLATE
BATTERY CHARGING..................10
STANDARD PROCEDURE -
CONVENTIONAL BATTERY CHARGING.....11
STANDARD PROCEDURE - OPEN-CIRCUIT
VOLTAGE TEST.......................13
STANDARD PROCEDURE - IGNITION-OFF
DRAW TEST.........................13
STANDARD PROCEDURE - CHECKING
BATTERY ELECTROLYTE LEVEL.........14REMOVAL - BATTERY...................14
INSTALLATION.........................15
BATTERY HOLDDOWN
DESCRIPTION.........................15
OPERATION...........................15
REMOVAL.............................15
INSTALLATION.........................16
BATTERY CABLES
DESCRIPTION.........................16
OPERATION...........................16
DIAGNOSIS AND TESTING - BATTERY CABLE . 16
REMOVAL.............................18
INSTALLATION.........................18
BATTERY TRAY
DESCRIPTION.........................18
OPERATION...........................19
REMOVAL.............................19
INSTALLATION.........................19
THERMOWRAP
DESCRIPTION.........................19
OPERATION...........................20
REMOVAL.............................20
INSTALLATION.........................20
BATTERY SYSTEM
DESCRIPTION
A single 12-volt battery system is standard factory-
installed equipment on this model. All of the compo-
nents of the battery system are located within the
engine compartment of the vehicle. The service infor-
mation for the battery system in this vehicle coversthe following related components, which are covered
in further detail elsewhere in this service manual:
²Battery- The storage battery provides a reli-
able means of storing a renewable source of electrical
energy within the vehicle.
²Battery Cable- The battery cables connect the
battery terminal posts to the vehicle electrical sys-
tem.
RSENGINE SYSTEMS8F-1
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²Battery Holddown- The battery holddown
hardware secures the battery in the battery tray in
the engine compartment.
²Battery Thermowrap- The battery ther-
mowarp insulates the battery to protect it from
engine compartment temperature extremes.
²Battery Tray- The battery tray provides a
secure mounting location in the vehicle for the bat-
tery and an anchor point for the battery holddown
hardware.
For battery system maintenance schedules and
jump starting procedures, see the owner's manual in
the vehicle glove box. Optionally, refer to Lubrication
and Maintenance for the recommended battery main-
tenance schedules and for the proper battery jump
starting procedures. While battery charging can be
considered a maintenance procedure, the battery
charging procedures and related information are
located in the standard procedures section of this ser-
vice manual. This was done because the battery must
be fully-charged before any battery system diagnosis
or testing procedures can be performed. Refer to
Standard procedures for the proper battery charging
procedures.
OPERATION
The battery system is designed to provide a safe,
efficient, reliable and mobile means of delivering and
storing electrical energy. This electrical energy is
required to operate the engine starting system, as
well as to operate many of the other vehicle acces-
sory systems for limited durations while the engine
and/or the charging system are not operating. The
battery system is also designed to provide a reserve
of electrical energy to supplement the charging sys-
tem for short durations while the engine is running
and the electrical current demands of the vehicle
exceed the output of the charging system. In addition
to delivering, and storing electrical energy for the
vehicle, the battery system serves as a capacitor and
voltage stabilizer for the vehicle electrical system. It
absorbs most abnormal or transient voltages caused
by the switching of any of the electrical components
or circuits in the vehicle.
DIAGNOSIS AND TESTING - BATTERY SYSTEM
The battery, starting, and charging systems in the
vehicle operate with one another and must be tested
as a complete system. In order for the engine to start
and the battery to maintain its charge properly, all of
the components that are used in these systems must
perform within specifications. It is important that
the battery, starting, and charging systems be thor-
oughly tested and inspected any time a battery needs
to be charged or replaced. The cause of abnormal bat-
tery discharge, overcharging or early battery failure
must be diagnosed and corrected before a battery is
replaced and before a vehicle is returned to service.
The service information for these systems has been
separated within this service manual to make it eas-
ier to locate the specific information you are seeking.
However, when attempting to diagnose any of these
systems, it is important that you keep their interde-
pendency in mind.
The diagnostic procedures used for the battery,
starting, and charging systems include the most
basic conventional diagnostic methods, to the more
sophisticated On-Board Diagnostics (OBD) built into
the Powertrain Control Module (PCM). Use of an
induction-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for any failure it detects. Refer to
Charging System for the proper charging system on-
board diagnostic test procedures.
MICRO 420 ELECTRICAL SYSTEM TESTER
The Micro 420 automotive battery system tester is
designed to help the dealership technicians diagnose
the cause of a defective battery. Follow the instruc-
tion manual supplied with the tester to properly
diagnose a vehicle. If the instruction manual is not
available refer to the standard procedure in this sec-
tion, which includes the directions for using the
Micro 420 electrical system tester.
8F - 2 BATTERY SYSTEMRS
BATTERY SYSTEM (Continued)
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BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY SEEMS
WEAK OR DEAD WHEN
ATTEMPTING TO START
THE ENGINE.1. The electrical system
ignition-off draw is excessive.1. Refer to the IGNITION-OFF DRAW TEST
Standard Procedure for the proper test
procedures. Repair the excessive ignition-off
draw, as required.
2. The charging system is
faulty.2. Determine if the charging system is performing
to specifications. Refer to Charging System for
additional charging system diagnosis and testing
procedures. Repair the faulty charging system, as
required.
3. The battery is discharged. 3. Determine the battery state-of-charge using the
Micro 420 battery tester. Refer to the Standard
Procedures in this section for additional test
procedures. Charge the faulty battery, as
required.
4. The battery terminal
connections are loose or
corroded.4. Refer to Battery Cables for the proper battery
cable diagnosis and testing procedures. Clean
and tighten the battery terminal connections, as
required.
5. The battery has an
incorrect size or rating for
this vehicle.5. Refer to Battery System Specifications for the
proper size and rating. Replace an incorrect
battery, as required.
6. The battery is faulty. 6. Test the battery using the Micro 420 battery
tester. Refer to the Standard Procedures in this
section for additional test procedures. Replace
the faulty battery, as required.
7. The starting system is
faulty.7. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
8. The battery is physically
damaged.8. Inspect the battery for loose terminal posts or a
cracked and leaking case. Replace the damaged
battery, as required.
RSBATTERY SYSTEM8F-3
BATTERY SYSTEM (Continued)
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BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY STATE OF
CHARGE CANNOT BE
MAINTAINED.1. The battery has an
incorrect size or rating for
this vehicle.1. Refer to Battery System Specifications for the
proper specifications. Replace an incorrect
battery, as required.
2. The battery terminal
connections are loose or
corroded.2. Refer to Battery Cable for the proper cable
diagnosis and testing procedures. Clean and
tighten the battery terminal connections, as
required.
3. The electrical system
ignition-off draw is excessive.3. Refer to the IGNITION-OFF DRAW TEST
Standard Procedure for the proper test
procedures. Repair the faulty electrical system, as
required.
4. The battery is faulty. 4. Test the battery using the Micro 420 battery
tester. Refer to Standard Procedures for
additional test procedures. Replace the faulty
battery, as required.
5. The starting system is
faulty.5. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
6. The charging system is
faulty.6. Determine if the charging system is performing
to specifications. Refer to Charging System for
charging system diagnosis and testing
procedures. Repair the faulty charging system, as
required.
7. Electrical loads exceed the
output of the charging
system.7. Inspect the vehicle for aftermarket electrical
equipment which might cause excessive electrical
loads.
8. Slow driving or prolonged
idling with high-amperage
draw loads in use.8. Advise the vehicle operator, as required.
THE BATTERY WILL NOT
ACCEPT A CHARGE.1. The battery is faulty. 1. Test the battery using the Micro 420 battery
tester.. Charge or replace the faulty battery, as
required.
ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal battery discharging:
1. A faulty or incorrect charging system compo-
nent. Refer to Charging System for additional charg-
ing system diagnosis and testing procedures.
2. A faulty or incorrect battery. Use Micro 420
tester and refer to Battery System for additional bat-
tery diagnosis and testing procedures.
3. A faulty circuit or component causing excessive
ignition-off draw.
4. Electrical loads that exceed the output of the
charging system. This can be due to equipmentinstalled after manufacture, or repeated short trip
use.
5. A faulty or incorrect starting system component.
Refer to Starting System for the proper starting sys-
tem diagnosis and testing procedures.
6. Corroded or loose battery posts and/or terminal
clamps.
7. Slow driving speeds (heavy traffic conditions) or
prolonged idling, with high-amperage draw loads in
use.
8F - 4 BATTERY SYSTEMRS
BATTERY SYSTEM (Continued)
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