Dodge Electronic Control Modules Service Manual
DR ELECTRONIC CONTROL MODULES 8E - 1
ELECTRONIC CONTROL MODULES
TABLE OF CONTENTS
page page
COMMUNICATION
DESCRIPTION ..........................1
OPERATION ............................2
CONTROLLER ANTILOCK BRAKE
DESCRIPTION ..........................3
OPERATION ............................3
REMOVAL .............................3
INSTALLATION ..........................3
DATA LINK CONNECTOR
DESCRIPTION - DATA LINK CONNECTOR .....3
OPERATION - DATA LINK CONNECTOR ......3
ENGINE CONTROL MODULE
DESCRIPTION - ECM .....................4
OPERATION - ECM ......................4
REMOVAL .............................4
INSTALLATION ..........................5
FRONT CONTROL MODULE
DESCRIPTION ..........................5
OPERATION ............................5
DIAGNOSIS AND TESTING - FRONT
CONTROL MODULE ....................6
REMOVAL .............................6
INSTALLATION ..........................6
HEATED SEAT MODULE
DESCRIPTION ..........................6
OPERATION ............................6
DIAGNOSIS AND TESTING - HEATED SEAT
MODULE .............................7
REMOVAL .............................7
INSTALLATION ..........................7
POWERTRAIN CONTROL MODULE
DESCRIPTION
DESCRIPTION - PCM ...................8
DESCRIPTION - MODES OF OPERATION ....8
DESCRIPTION - 5 VOLT SUPPLIES .......10
DESCRIPTION - IGNITION CIRCUIT SENSE . 10
DESCRIPTION - POWER GROUNDS ......10
DESCRIPTION - SENSOR RETURN .......10
OPERATION
OPERATION - PCM ....................11
OPERATION - 5 VOLT SUPPLIES .........11
OPERATION - IGNITION CIRCUIT SENSE . . . 12
REMOVAL .............................12
INSTALLATION .........................12
SENTRY KEY IMMOBILIZER MODULE
DESCRIPTION .........................13
OPERATION ...........................13
STANDARD PROCEDURE - PCM/SKIM
PROGRAMMING ......................14
REMOVAL .............................15
INSTALLATION .........................15
TRANSFER CASE CONTROL MODULE
DESCRIPTION .........................15
OPERATION ...........................15
TRANSMISSION CONTROL MODULE
DESCRIPTION .........................19
OPERATION ...........................19
STANDARD PROCEDURE
STANDARD PROCEDURE - TCM QUICK
LEARN..............................21
STANDARD PROCEDURE - DRIVE LEARN . . 21
COMMUNICATION
DESCRIPTION
The DaimlerChrysler Programmable Communication Interface (PCI) data bus system is a single wire
multiplex system used for vehicle communications on
many DaimlerChrysler Corporation vehicles. Multi-
plexing is a system that enables the transmission of
several messages over a single channel or circuit. All
DaimlerChrysler vehicles use this principle for communication between various microprocessor-based
electronic control modules. The PCI data bus exceeds
the Society of Automotive Engineers (SAE) J1850
Standard for Class B Multiplexing.
8E - 2 ELECTRONIC CONTROL MODULES DR
COMMUNICATION (Continued)
Many of the electronic control modules in a vehicle
require information from the same sensing device. In
the past, if information from one sensing device was
required by several controllers, a wire from each controller needed to be connected in parallel to that sensor. In addition, each controller utilizing analog
sensors required an Analog/Digital (A/D) converter in
order to 9read9 these sensor inputs. Multiplexing
reduces wire harness complexity, sensor current
loads and controller hardware because each sensing
device is connected to only one controller, which
reads and distributes the sensor information to the
other controllers over the data bus. Also, because
each controller on the data bus can access the controller sensor inputs to every other controller on the
data bus, more function and feature capabilities are
possible.
In addition to reducing wire harness complexity,
component sensor current loads and controller hardware, multiplexing offers a diagnostic advantage. A
multiplex system allows the information flowing
between controllers to be monitored using a diagnostic scan tool. The DaimlerChrysler system allows an
electronic control module to broadcast message data
out onto the bus where all other electronic control
modules can 9hear9 the messages that are being sent.
When a module hears a message on the data bus
that it requires, it relays that message to its microprocessor. Each module ignores the messages on the
data bus that are being sent to other electronic control modules.
OPERATION
Data exchange between modules is achieved by
serial transmission of encoded data over a single wire
broadcast network. The wire colors used for the PCI
data bus circuits are yellow with a violet tracer, or
violet with a yellow tracer, depending upon the application. The PCI data bus messages are carried over
the bus in the form of Variable Pulse Width Modulated (VPWM) signals. The PCI data bus speed is an
average 10.4 Kilo-bits per second (Kbps). By comparison, the prior two-wire Chrysler Collision Detection
(CCD) data bus system is designed to run at 7.8125
Kbps.
The voltage network used to transmit messages
requires biasing and termination. Each module on
the PCI data bus system provides its own biasing
and termination. Each module (also referred to as a
node) terminates the bus through a terminating
resistor and a terminating capacitor. There are two
types of nodes on the bus. The dominant node terminates the bus througha1KWresistor and a 3300 pF
capacitor. The Powertrain Control Module (PCM) is
the only dominant node for the PCI data bus system.
A standard node terminates the bus through an 11
KW resistor and a 330 pF capacitor.
The modules bias the bus when transmitting a
message. The PCI bus uses low and high voltage levels to generate signals. Low voltage is around zero
volts and the high voltage is about seven and onehalf volts. The low and high voltage levels are generated by means of variable-pulse width modulation to
form signals of varying length. The Variable Pulse
Width Modulation (VPWM) used in PCI bus messaging is a method in which both the state of the bus
and the width of the pulse are used to encode bit
information. A 9zero9 bit is defined as a short low
pulse or a long high pulse. A 9one9 bit is defined as a
long low pulse or a short high pulse. A low (passive)
state on the bus does not necessarily mean a zero bit.
It also depends upon pulse width. If the width is
short, it stands for a zero bit. If the width is long, it
stands for a one bit. Similarly, a high (active) state
does not necessarily mean a one bit. This too depends
upon pulse width. If the width is short, it stands for
a one bit. If the width is long, it stands for a zero bit.
In the case where there are successive zero or one
data bits, both the state of the bus and the width of
the pulse are changed alternately. This encoding
scheme is used for two reasons. First, this ensures
that only one symbol per transition and one transition per symbol exists. On each transition, every
transmitting module must decode the symbol on the
bus and begin timing of the next symbol. Since timing of the next symbol begins with the last transition
detected on the bus, all of the modules are re-synchronized with each symbol. This ensures that there
are no accumulated timing errors during PCI data
bus communication.
The second reason for this encoding scheme is to
guarantee that the zero bit is the dominant bit on
the bus. When two modules are transmitting simultaneously on the bus, there must be some form of
arbitration to determine which module will gain control. A data collision occurs when two modules are
transmitting different messages at the same time.
When a module is transmitting on the bus, it is reading the bus at the same time to ensure message
integrity. When a collision is detected, the module
that transmitted the one bit stops sending messages
over the bus until the bus becomes idle.
Each module is capable of transmitting and receiving data simultaneously. The typical PCI bus message has the following four components:
• Message Header - One to three bytes in length.
The header contains information identifying the message type and length, message priority, target module(s) and sending module.
• Data Byte(s) - This is the actual message that
is being sent.
DR ELECTRONIC CONTROL MODULES 8E - 3
COMMUNICATION (Continued)
• Cyclic Redundancy Check (CRC) Byte - This
byte is used to detect errors during a message transmission.
• In-Frame Response (IFR) byte(s) -Ifa
response is required from the target module(s), it can
be sent during this frame. This function is described
in greater detail in the following paragraph.
The IFR consists of one or more bytes, which are
transmitted during a message. If the sending module
requires information to be received immediately, the
target module(s) can send data over the bus during
the original message. This allows the sending module
to receive time-critical information without having to
wait for the target module to access the bus. After
the IFR is received, the sending module broadcasts
an End of Frame (EOF) message and releases control
of the bus.
The PCI data bus can be monitored using the
DRBIIIt scan tool. It is possible, however, for the bus
to pass all DRBIIIt tests and still be faulty if the
voltage parameters are all within the specified range
and false messages are being sent.
CONTROLLER ANTILOCK
BRAKE
DESCRIPTION
The Controler Antilock Brake (CAB) is mounted to
the Hydraulic Control Unit (HCU) and operates the
ABS system (Fig. 1).
OPERATION
The CAB voltage source is through the ignition
switch in the RUN position. The CAB contains a self
check program that illuminates the ABS warning
light when a system fault is detected. Faults are
stored in a diagnostic program memory and are
accessible with the DRB III scan tool. ABS faults
remain in memory until cleared, or until after the
vehicle is started approximately 50 times. Stored
faults are not erased if the battery is disconnected.
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
REMOVAL
(1) Remove the negative battery cable from the
battery.
(2) Pull up on the CAB harness connector release
and remove connector.
(3) Remove the CAB mounting bolts.
(4) Remove the pump connector from the CAB.
(5) Remove the CAB from the HCU.
INSTALLATION
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
(1) Install CAB to the HCU.
(2) Install the pump connector to the CAB.
(3) Install mounting bolts. Tighten to 2 N·m (16 in.
lbs.).
(4) Install the wiring harness connector to the
CAB and push down on the release to secure the connector.
(5) Install negative battery cable to the battery.
Fig. 1 HYDRAULIC CONTROL UNIT
1 - HYDRAULIC CONTROL UNIT
2 - MOUNTING BOLTS
DATA LINK CONNECTOR
DESCRIPTION - DATA LINK CONNECTOR
The Data Link Connector (DLC) is located at the
lower edge of the instrument panel near the steering
column.
OPERATION - DATA LINK CONNECTOR
The 16–way data link connector (diagnostic scan
tool connector) links the Diagnostic Readout Box
(DRB) scan tool or the Mopar Diagnostic System
(MDS) with the Powertrain Control Module (PCM).
8E - 4 ELECTRONIC CONTROL MODULES DR
ENGINE CONTROL MODULE
DESCRIPTION - ECM
The Engine Control Module (ECM) is bolted to the
left side of the engine below the intake manifold (Fig.
2).
NOTE: ECM Inputs:
• Accelerator Pedal Position Sensor (APPS) Volts
• APPS1 Signal — For off engine APPS
• APPS2 Signal — For off engine APPS
• APPS Idle Validation Switches #1 and #2
• Battery voltage
• Camshaft Position Sensor (CMP)
• CCD bus (+) circuits
• CCD bus (-) circuits
• Crankshaft Position Sensor (CKP)
• Data link connection for DRB scan tool
• Engine Coolant Temperature (ECT) sensor
• Ground circuits
• Fuel Pressure Sensor
• Battery Temperature
• Fan speed
• Inlet Air Temperature Sensor/Pressure Sensor
• Intake Air Temperature Sensor/MAP Sensor
• Oil Pressure SWITCH
• Power ground
• Sensor return
• Signal ground
• Water-In-Fuel (WIF) sensor
Fig. 2 DIESEL ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
OPERATION - ECM
The main function of the Engine Control Module
(ECM) is to electrically control the fuel system. The
Powertrain Control Module (PCM) does not control
the fuel system.
The ECM can adapt its programming to meet
changing operating conditions. If the ECM has
been replaced, flashed or re-calibrated, the
ECM must learn the Accelerator Pedal Position
Sensor (APPS) idle voltage. Failure to learn
this voltage may result in unnecessary diagnostic trouble codes. Refer to ECM Removal/Installation for learning procedures.
The ECM receives input signals from various
switches and sensors. Based on these inputs, the
ECM regulates various engine and vehicle operations
through different system components. These components are referred to as ECM Outputs. The sensors
and switches that provide inputs to the ECM are
considered ECM Inputs.
NOTE: ECM Outputs:
After inputs are received by the ECM, certain sensors, switches and components are controlled or regulated by the ECM. These are considered ECM
Outputs. These outputs are for:
• CCD bus (+) circuits
• CCD bus (-) circuits
• CKP and APPS outputs to the PCM
• Data link connection for DRB scan tool
• Five volt sensor supply
• Fuel transfer (lift) pump
• Intake manifold air heater relays #1 and #2 con-
trol circuits
• Malfunction indicator lamp (Check engine lamp)
(databus)
• Oil Pressure Swith/warning lamp (databus)
• Fuel Control Actuator
• Wait-to-start warning lamp (databus)
• Fan Clutch PWM
• Water-In-Fuel (WIF) warning lamp (databus)
REMOVAL
The Engine Control Module (ECM) is bolted to a
support bracket near the fuel filter. The support
bracket mounts to the block with four capscrews and
vibration isolators. A ground wire is fastened to the
bracket. The other end of the wire is fastened to the
engine block.
(1) Record any Diagnostic Trouble Codes (DTC’s)
found in the ECM.
DR ELECTRONIC CONTROL MODULES 8E - 5
ENGINE CONTROL MODULE (Continued)
To avoid possible voltage spike damage to either
the Engine Control Module ECM, ignition key must
be off, and negative battery cables must be disconnected before unplugging ECM connectors.
(2) Disconnect both negative battery cables at both
batteries.
(3) Remove the 50–way and 60–way connector
bolts at the ECM. Note: Tthe connector bolt is a
female allen head. As bolt is being removed, very carfully remove connectors from the ECM.
(4) Remove five ECM mounting bolts and remove
ECM form the vehicle (Fig. 3).
(6) Turn key to ON position. Without starting
engine, slowly press throttle pedal to floor and
then slowly release. This step must be done
(one time) to ensure accelerator pedal position
sensor calibration has been learned by ECM. If
not done, possible DTC’s may be set.
(7) Use DRB scan tool to erase any stored compan-
ion DTC’s from ECM.
FRONT CONTROL MODULE
DESCRIPTION
The Front Control Module (FCM) is a micro controller based module located in the left front corner
of the engine compartment. On this model the integrated power module must be positioned aside in
order to access the front control module. The front
control module mates to the power distribution center to form the Integrated Power Module (IPM). The
integrated power module connects directly to the battery and provides the primary means of circuit protection and power distribution for all vehicle
electrical systems. The front control module controls
power to some of these vehicle systems electrical and
electromechanical loads based on inputs received
from hard wired switch inputs and data received on
the PCI bus circuit (J1850).
For information on the Integrated Power Mod-
ule Refer to the Power Distribution Section of
the service manual.
Fig. 3 DIESEL ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
INSTALLATION
Do not apply paint to ECM. Poor ground will
result.
(1) Position ECM to ECM support bracket and
install five mounting bolts. Tighten bolts to 24 N·m
(18 ft. lbs.).
(2) Check pin connectors in ECM and the 50–way
and 60–way connectors for corrosion or damage.
Repair as necessary.
(3) Clean pins in the 50–way and 60–way electrical connectors with a quick-dry electrical contact
cleaner.
(4) Very carefully install the 50–way and 60–way
connectors to ECM. Tighten connector allen bolts.
(5) Install both negative battery cables.
OPERATION
As messages are sent over the PCI bus circuit, the
front control module reads these messages and controls power to some of the vehicles electrical systems
by completing the circuit to ground (low side driver)
or completing the circuit to 12 volt power (high side
driver). The following functions are Controlled by
the Front Control Module:
• Headlamp Power with Voltage Regulation
• Windshield Wiper “ON/OFF” Relay Actuation
• Windshield Wiper “HI/LO” Relay Actuation
• Windshield Washer Pump Motor
• Fog Lamp Relay Actuation
• Park Lamp Relay Actuation
• Horn Relay Actuation
The following inputs are Received/Monitored by
the Front Control Module:
• B+ Connection Detection
• Power Ground
• Ambient Temperature Sensing
• Ignition Switch Run
• Washer Fluid Level Switch
• Windshield Wiper Park Switch
• PCI Bus Circuit
8E - 6 ELECTRONIC CONTROL MODULES DR
FRONT CONTROL MODULE (Continued)
DIAGNOSIS AND TESTING - FRONT CONTROL
MODULE
The front control module is a printed circuit board
based module with a on-board micro-processor. The
front control module interfaces with other electronic
modules in the vehicle via the Programmable Communications Interface (PCI) data bus (J1850). In
order to obtain conclusive testing the Programmable
Communications Interface (PCI) data bus network
and all of the electronic modules that provide inputs
to, or receive outputs from the front control module
must be checked. All PCI (J1850) communication
faults must be resolved prior to further diagnosing
any front control module related issues.
The front control module was designed to be diagnosed with an appropriate diagnostic scan tool, such
as the DRB IIIt. The most reliable, efficient, and
accurate means to diagnose the front control module
requires the use of a DRB IIIt scan tool and the
proper Body Diagnostic Procedures manual.
Before any testing of the front control module is
attempted, the battery should be fully charged and
all wire harness and ground connections inspected
around the affected areas on the vehicle.
REMOVAL
(1) Disconnect the positive and negative battery
cables from the battery.
(2) Partially remove the integrated power module
from the engine compartment (Refer to 8 - ELECTRICAL/POWER DISTRIBUTION/INTEGRATED
POWER MODULE - REMOVAL).
(3) Remove the front control module retaining
screws.
(4) Using both hands, pull the front control module
straight from the integrated power module assembly
to disconnect the 49-way electrical connector and
remove the front control module from the vehicle.
INSTALLATION
(1) Install the front control module on the integrated power module assembly by pushing the
49-way electrical connector straight in.
(2) Install the front control module retaining
screws. Torque the screws to 7 in. lbs.
(3) Install the integrated power module (Refer to 8
- ELECTRICAL/POWER DISTRIBUTION/INTEGRATED POWER MODULE - INSTALLATION).
(4) Connect the positive and negative battery
cables.
HEATED SEAT MODULE
DESCRIPTION
Fig. 4 Heated Seat Module
1 - MOUNTING TABS (NOT USED ON DR)
2 - HEATED SEAT MODULE
3 - ELECTRICAL CONNECTOR RECEPTACLE
The heated seat module is also known as the Seat
Heat Interface Module. The heated seat module (Fig.
4) is located under the drivers front seat cushion,
where it is secured to a mounting bracket. The
heated seat module has a single connector receptacle
that allows the module to be connected to all of the
required inputs and outputs through the seat wire
harness.
The heated seat module is an electronic microprocessor controlled device designed and programmed to
use inputs from the battery, the two heated seat
switches and the two heated seat sensors to operate
and control the heated seat elements in both front
seats and the two heated seat indicator lamp LightEmitting Diodes (LEDs) in each heated seat switch.
The heated seat module is also programmed to perform self-diagnosis of certain heated seat system
functions and provide feedback of that diagnosis
through the heated seat switch indicator lamps.
The heated seat module cannot be repaired. If the
heated seat module is damaged or faulty, the entire
module must be replaced.
OPERATION
The heated seat module operates on fused battery
current received from the integrated power module.
Inputs to the module include a resistor multiplexed
heated seat switch request circuit for each of the two
heated seat switches and the heated seat sensor
inputs from the seat cushions of each front seat. In
response to those inputs the heated seat module controls battery current feeds to the heated seat ele-
DR ELECTRONIC CONTROL MODULES 8E - 7
HEATED SEAT MODULE (Continued)
ments and sensors, and controls the ground for the
heated seat switch indicator lamps.
When a heated seat switch (Driver or Passenger) is
depressed a signal is received by the heated seat
module, the module energizes the proper indicator
LED (Low or High) in the switch by grounding the
indicator lamp circuit to indicate that the heated seat
system is operating. At the same time, the heated
seat module energizes the selected heated seat sensor
circuit and the sensor provides the module with an
input indicating the surface temperature of the
selected seat cushion.
The Low heat set point is about 36° C (96.8° F),
and the High heat set point is about 42° C (107.6° F).
If the seat cushion surface temperature input is
below the temperature set point for the selected temperature setting, the heated seat module energizes
an N-channel Field Effect Transistor (N-FET) within
the module which energizes the heated seat elements
in the selected seat cushion and back. When the sensor input to the module indicates the correct temperature set point has been achieved, the module
de-energizes the N-FET which de-energizes the
heated seat elements. The heated seat module will
continue to cycle the N-FET as needed to maintain
the selected temperature set point.
If the heated seat module detects a heated seat
sensor value input that is out of range or a shorted
or open heated seat element circuit, it will notify the
vehicle operator or the repair technician of this condition by flashing the High and/or Low indicator
lamps in the affected heated seat switch. Refer to
Diagnosis and Testing Heated Seat System in
Heated Systems for flashing LED diagnosis and testing procedures. Refer to Diagnosis and Testing
Heated Seat Module in this section for heated seat
module diagnosis and testing procedures.
DIAGNOSIS AND TESTING - HEATED SEAT
MODULE
If a heated seat fails to heat and one or both of the
indicator lamps on a heated seat switch flash, refer
to Diagnosis and Testing Heated Seat System in
Heated Seats for the location of flashing LED heated
seat system diagnosis and testing procedures. If a
heated seat heats but one or both indicator lamps on
the heated seat switch fail to operate, test the heated
seat switch. Refer to Diagnosis and Testing
Heated Seat Switch in 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) Position the driver seat to the full rearward
and inclined position.
(2) Working under the driver front seat, remove
the two heated seat module retaining screws. Due to
the fact that the retaining screws are installed with
the seat cushion pan removed, a small right angle
screwdriver will be required to access and remove the
screws.
(3) Disconnect the seat wire harness connector
from the connector receptacle on the back of the
heated seat module. Depress the connector retaining
tab and pull straight apart.
(4) Remove the heated seat module from under the
front seat.
INSTALLATION
(1) Position the heated seat module under the
front seat.
(2) Connect the seat wire harness connector on the
connector receptacle on the back of the heated seat
module.
(3) Working under the driver front seat, install the
heated seat module retaining screws.
(4) Re-position the driver seat.
8E - 8 ELECTRONIC CONTROL MODULES DR
POWERTRAIN CONTROL
MODULE
DESCRIPTION
DESCRIPTION - PCM
The Powertrain Control Module (PCM) is located
in the right-rear section of the engine compartment
under the cowl (Fig. 5).
Two different PCM’s are used (JTEC and
NGC). These can be easily identified. JTEC’s
use three 32–way connectors, NGC’s use four
38–way connectors
During Closed Loop modes, the PCM will monitor
the oxygen (O2S) sensors input. This input indicates
to the PCM whether or not the calculated injector
pulse width results in the ideal air-fuel ratio. This
ratio is 14.7 parts air-to-1 part fuel. By monitoring
the exhaust oxygen content through the O2S sensor,
the PCM can fine tune the injector pulse width. This
is done to achieve optimum fuel economy combined
with low emission engine performance.
The fuel injection system has the following modes
of operation:
• Ignition switch ON
• Engine start-up (crank)
• Engine warm-up
• Idle
• Cruise
• Acceleration
• Deceleration
• Wide open throttle (WOT)
• Ignition switch OFF
The ignition switch On, engine start-up (crank),
engine warm-up, acceleration, deceleration and wide
open throttle modes are Open Loop modes. The idle
and cruise modes, (with the engine at operating temperature) are Closed Loop modes.
Fig. 5 POWERTRAIN CONTROL MODULE (PCM)
LOCATION
1 - COWL GRILL
2 - PCM
3 - COWL (RIGHT-REAR)
DESCRIPTION - MODES OF OPERATION
As input signals to the Powertrain Control Module
(PCM) change, the PCM adjusts its response to the
output devices. For example, the PCM must calculate
different injector pulse width and ignition timing for
idle than it does for wide open throttle (WOT).
The PCM will operate in two different modes:
Open Loop and Closed Loop.
During Open Loop modes, the PCM receives input
signals and responds only according to preset PCM
programming. Input from the oxygen (O2S) sensors
is not monitored during Open Loop modes.
IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system
is activated by the ignition switch, the following
actions occur:
• The PCM pre-positions the idle air control (IAC)
motor.
• The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel
strategy.
• The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy
based on this input.
• Intake manifold air temperature sensor input is
monitored.
• Throttle position sensor (TPS) is monitored.
• The auto shutdown (ASD) relay is energized by
the PCM for approximately three seconds.
• The fuel pump is energized through the fuel
pump relay by the PCM. The fuel pump will operate
for approximately three seconds unless the engine is
operating or the starter motor is engaged.
• The O2S sensor heater element is energized via
the ASD or O2S heater relay. The O2S sensor input
is not used by the PCM to calibrate air-fuel ratio during this mode of operation.
ENGINE START-UP MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The PCM receives inputs from:
DR ELECTRONIC CONTROL MODULES 8E - 9
POWERTRAIN CONTROL MODULE (Continued)
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal
The PCM monitors the crankshaft position sensor.
If the PCM does not receive a crankshaft position
sensor signal within 3 seconds of cranking the
engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage 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.
The PCM determines the proper ignition timing
according to input received from the crankshaft position sensor.
ENGINE WARM-UP MODE
This is an Open Loop mode. During engine warmup, the PCM receives inputs from:
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal
• Park/neutral switch (gear indicator signal—auto.
trans. only)
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
Based on these inputs the following occurs:
• Voltage 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.
• The PCM adjusts engine idle speed through the
idle air control (IAC) motor and adjusts ignition timing.
• The PCM operates the A/C compressor clutch
through the A/C compressor clutch relay. This is done
if A/C has been selected by the vehicle operator and
specified pressures are met at the high and low–pressure A/C switches. Refer to Heating and Air Conditioning for additional information.
• When engine has reached operating temperature, 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:
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal
• Battery voltage
• Park/neutral switch (gear indicator signal—auto.
trans. only)
• Oxygen sensors
Based on these inputs, the following occurs:
• Voltage 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 turning the ground circuit to each individual injector on
and off.
• The 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.
• The PCM adjusts ignition timing by increasing
and decreasing spark advance.
• The PCM operates the A/C compressor clutch
through the A/C compressor clutch relay. This is done
if A/C has been selected by the vehicle operator and
specified pressures are met at the high and low–pressure A/C switches. Refer to Heating and Air Conditioning for additional information.
CRUISE MODE
When the engine is at operating temperature, this
is a Closed Loop mode. At cruising speed, the PCM
receives inputs from:
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal
• Park/neutral switch (gear indicator signal—auto.
trans. only)
• Oxygen (O2S) sensors
Based on these inputs, the following occurs:
• Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then adjust
8E - 10 ELECTRONIC CONTROL MODULES DR
POWERTRAIN CONTROL MODULE (Continued)
the injector pulse width by turning the ground circuit
to each individual injector on and off.
• The PCM monitors the O2S sensor input and
adjusts air-fuel ratio. It also adjusts engine idle
speed through the idle air control (IAC) motor.
• The PCM adjusts ignition timing by turning the
ground path to the coil(s) on and off.
• The 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 pressure 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.
• Air conditioning select signal (if equipped)
• Air conditioning request signal (if equipped)
• Battery voltage
• Engine coolant temperature sensor
• Crankshaft position sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal
• Park/neutral switch (gear indicator signal—auto.
trans. only)
• Vehicle speed
If the vehicle is under hard deceleration with the
proper rpm and closed throttle conditions, the PCM
will ignore the oxygen sensor input signal. The PCM
will enter a fuel cut-off strategy in which it will not
supply a ground to the injectors. If a hard deceleration does not exist, the PCM will determine the
proper injector pulse width and continue injection.
Based on the above inputs, the PCM will adjust
engine idle speed through the idle air control (IAC)
motor.
The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
WIDE OPEN THROTTLE MODE
This is an Open Loop mode. During wide open
throttle operation, the PCM receives the following
inputs.
• Battery voltage
• Crankshaft position sensor
• Engine coolant temperature sensor
• Intake manifold air temperature sensor
• Manifold absolute pressure (MAP) sensor
• Throttle position sensor (TPS)
• Camshaft position sensor signal
During wide open throttle conditions, the following
occurs:
• Voltage 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. The PCM ignores the oxygen sensor input
signal and provides a predetermined amount of additional fuel. This is done by adjusting injector pulse
width.
• The PCM adjusts ignition timing by turning the
ground path to the coil(s) on and off.
IGNITION SWITCH OFF MODE
When ignition switch is turned to OFF position,
the PCM stops operating the injectors, ignition coil,
ASD relay and fuel pump relay.
DESCRIPTION - 5 VOLT SUPPLIES
Two different Powertrain Control Module (PCM)
five volt supply circuits are used; primary and secondary.
DESCRIPTION - IGNITION CIRCUIT SENSE
This circuit ties the ignition switch to the Powertrain Control Module (PCM).
DESCRIPTION - POWER GROUNDS
The Powertrain Control Module (PCM) has 2 main
grounds. Both of these grounds are referred to as
power grounds. All of the high-current, noisy, electrical devices are connected to these grounds as well as
all of the sensor returns. The sensor return comes
into the sensor return circuit, passes through noise
suppression, and is then connected to the power
ground.
The power ground is used to control ground circuits for the following PCM loads:
• Generator field winding
• Fuel injectors
• Ignition coil(s)
• Certain relays/solenoids
• Certain sensors
DESCRIPTION - SENSOR RETURN
The Sensor Return circuits are internal to the Powertrain Control Module (PCM).
Sensor Return provides a low–noise ground reference for all engine control system sensors. Refer to
Power Grounds for more information.
DR ELECTRONIC CONTROL MODULES 8E - 11
POWERTRAIN CONTROL MODULE (Continued)
OPERATION
OPERATION - PCM
The PCM operates the fuel system. The PCM is a
pre-programmed, triple microprocessor digital computer. It regulates ignition timing, air-fuel ratio,
emission control devices, charging system, certain
transmission features, speed control, air conditioning
compressor clutch engagement and idle speed. The
PCM can adapt its programming to meet changing
operating conditions.
The PCM receives input signals from various
switches and sensors. Based on these inputs, the
PCM regulates various engine and vehicle operations
through different system components. These components are referred to as Powertrain Control Module
(PCM) Outputs. The sensors and switches that provide inputs to the PCM are considered Powertrain
Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon
inputs it receives from sensors that react to: engine
rpm, manifold absolute pressure, engine coolant temperature, throttle position, transmission gear selection (automatic transmission), vehicle speed, power
steering pump pressure, and the brake switch.
The PCM adjusts idle speed based on inputs it
receives from sensors that react to: throttle position,
vehicle speed, transmission gear selection, engine
coolant temperature and from inputs it receives from
the air conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts
ignition coil dwell. The PCM also adjusts the generator charge rate through control of the generator
field and provides speed control operation.
NOTE: PCM Inputs:
• ABS module (if equipped)
• A/C request (if equipped with factory A/C)
• A/C select (if equipped with factory A/C)
• A/C pressure transducer
• Auto shutdown (ASD) sense
• Battery temperature sensor
• Battery voltage
• Brake switch
• J1850 bus (+) circuits
• J1850 bus (-) circuits
• Camshaft position sensor signal
• Crankshaft position sensor
• Data link connection for DRB scan tool
• EATX module (if equipped)
• Engine coolant temperature sensor
• Fuel level (through J1850 circuitry)
• Generator (battery voltage) output
• Ignition circuit sense (ignition switch in on/off/
crank/run position)
• Intake manifold air temperature sensor
• Knock sensors (2 on 3.7L engine)
• Leak detection pump (switch) sense (if equipped)
• Manifold absolute pressure (MAP) sensor
• Oil pressure
• Oxygen sensors
• Park/neutral switch (auto. trans. only)
• Power ground
• Power steering pressure switch (if equipped)
• Sensor return
• Signal ground
• Speed control multiplexed single wire input
• Throttle position sensor
• Transfer case switch (4WD range position)
• Vehicle speed signal
NOTE: PCM Outputs:
• A/C clutch relay
• Auto shutdown (ASD) relay
• J1850 bus (+/-) circuits for: speedometer, voltme-
ter, fuel gauge, oil pressure gauge/lamp, engine temp.
gauge and speed control warn. lamp
• Data link connection for DRB scan tool
• EGR valve control solenoid (if equipped)
• EVAP canister purge solenoid
• Five volt sensor supply (primary)
• Five volt sensor supply (secondary)
• Fuel injectors
• Fuel pump relay
• Generator field driver (-)
• Generator field driver (+)
• Idle air control (IAC) motor
• Ignition coil(s)
• Leak detection pump (if equipped)
• Malfunction indicator lamp (Check engine lamp).
Driven through J1850 circuits.
• Oxygen sensor heater relays
• Oxygen sensors (pulse width modulated)
• Radiator cooling fan relay (pulse width modu-
lated)
• Speed control vacuum solenoid
• Speed control vent solenoid
• Tachometer (if equipped). Driven through J1850
circuits.
• Transmission convertor clutch circuit. Driven
through J1850 circuits.
OPERATION - 5 VOLT SUPPLIES
Primary 5–volt supply:
• supplies the required 5 volt power source to the
Crankshaft Position (CKP) sensor.
• supplies the required 5 volt power source to the
Camshaft Position (CMP) sensor.
• supplies a reference voltage for the Manifold
Absolute Pressure (MAP) sensor.
8E - 12 ELECTRONIC CONTROL MODULES DR
POWERTRAIN CONTROL MODULE (Continued)
• supplies a reference voltage for the Throttle
Position Sensor (TPS) sensor.
Secondary 5–volt supply:
• supplies the required 5 volt power source to the
oil pressure sensor.
• supplies the required 5 volt power source for the
Vehicle Speed Sensor (VSS) (if equipped).
• supplies the 5 volt power source to the transmission pressure sensor (certain automatic transmissions).
OPERATION - IGNITION CIRCUIT SENSE
The ignition circuit sense input tells the PCM the
ignition switch has energized the ignition circuit.
Battery voltage is also supplied to the PCM
through the ignition switch when the ignition is in
the RUN or START position. This is referred to as
the 9ignition sense9 circuit and is used to 9wake up9
the PCM. Voltage on the ignition input can be as low
as 6 volts and the PCM will still function. Voltage is
supplied to this circuit to power the PCM’s 8-volt regulator and to allow the PCM to perform fuel, ignition
and emissions control functions.
REMOVAL
USE THE DRB SCAN TOOL TO REPROGRAM
THE NEW POWERTRAIN CONTROL MODULE
(PCM) WITH THE VEHICLES ORIGINAL IDENTIFICATION NUMBER (VIN) AND THE VEHICLES ORIGINAL MILEAGE. IF THIS STEP IS
NOT DONE, A DIAGNOSTIC TROUBLE CODE
(DTC) MAY BE SET.
The PCM is located in the engine compartment
attached to the dash panel (Fig. 6).
To avoid possible voltage spike damage to the
PCM, ignition key must be off, and negative battery
cable must be disconnected before unplugging PCM
connectors.
(1) Disconnect negative battery cable at battery.
(2) Remove cover over electrical connectors. Cover
snaps onto PCM.
(3) Carefully unplug the three 32–way connectors
(four 38–way connectors if equipped with NGC) from
PCM (Fig. 7).
(4) Remove three PCM mounting bolts (Fig. 7) and
remove PCM from vehicle.
1 - COWL GRILL
2 - PCM
3 - COWL (RIGHT-REAR)
Fig. 6 PCM LOCATION
INSTALLATION
USE THE DRB SCAN TOOL TO REPROGRAM
THE NEW POWERTRAIN CONTROL MODULE
(PCM) WITH THE VEHICLES ORIGINAL IDENTIFICATION NUMBER (VIN) AND THE VEHICLES ORIGINAL MILEAGE. IF THIS STEP IS
NOT DONE, A DIAGNOSTIC TROUBLE CODE
(DTC) MAY BE SET.
(1) Install PCM and 3 mounting bolts to vehicle.
Fig. 7 PCM REMOVAL / INSTALLATION
1 - THREE 32-WAY CONNECTORS WITH JTEC (FOUR 38-WAY
CONNECTORS WITH NGC)
2 - PCM MOUNTING BRACKET
3 - PCM
4 - PCM MOUNTING SCREWS (3)
DR ELECTRONIC CONTROL MODULES 8E - 13
POWERTRAIN CONTROL MODULE (Continued)
(2) Tighten bolts. Refer to torque specifications.
(3) Check pin connectors in the PCM and the three
32–way connectors (four 38–way connectors if
equipped with NGC) for corrosion or damage. Also,
the pin heights in connectors should all be same.
Repair as necessary before installing connectors.
(4) Install three 32–way connectors (four 38–way
connectors if equipped with NGC).
(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install negative battery cable.
(7) Use the DRB scan tool to reprogram new PCM
with vehicles original Vehicle Identification Number
(VIN) and original vehicle mileage.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) contains a Radio Frequency (RF) transceiver and a central processing unit, which includes the Sentry Key
Immobilizer System (SKIS) program logic. The SKIS
programming enables the SKIM to program and
retain in memory the codes of at least two, but no
more than eight electronically coded Sentry Key
transponders. The SKIS programming also enables
the SKIM to communicate over the Programmable
Communication Interface (PCI) bus network with the
Powertrain Control Module (PCM), and/or the
DRBIIIt scan tool.
OPERATION
The SKIM transmits and receives RF signals
through a tuned antenna enclosed within a molded
plastic ring that is integral to the SKIM housing.
When the SKIM is properly installed on the steering
column, the antenna ring is oriented around the ignition lock cylinder housing. This antenna ring must be
located within eight millimeters (0.31 inches) of the
Sentry Key in order to ensure proper RF communication between the SKIM and the Sentry Key transponder.
For added system security, each SKIM is programmed with a unique “Secret Key” code and a
security code. The SKIM keeps the “Secret Key” code
in memory. The SKIM also sends the “Secret Key”
code to each of the programmed Sentry Key transponders. The security code is used by the assembly
plant to access the SKIS for initialization, or by the
dealer technician to access the system for service.
The SKIM also stores in its memory the Vehicle
Identification Number (VIN), which it learns through
a PCI bus message from the PCM during initialization.
The SKIM and the PCM both use software that
includes a rolling code algorithm strategy, which
helps to reduce the possibility of unauthorized SKIS
disarming. The rolling code algorithm ensures security by preventing an override of the SKIS through
the unauthorized substitution of the SKIM or the
PCM. However, the use of this strategy also means
that replacement of either the SKIM or the PCM
units will require a system initialization procedure to
restore system operation.
When the ignition switch is turned to the ON or
START positions, the SKIM transmits an RF signal
to excite the Sentry Key transponder. The SKIM then
listens for a return RF signal from the transponder
of the Sentry Key that is inserted in the ignition lock
cylinder. If the SKIM receives an RF signal with
valid “Secret Key” and transponder identification
codes, the SKIM sends a “valid key” message to the
PCM over the PCI bus. If the SKIM receives an
invalid RF signal or no response, it sends “invalid
key” messages to the PCM. The PCM will enable or
disable engine operation based upon the status of the
SKIM messages.
The SKIM also sends messages to the Instrument
Cluster which controls the VTSS indicator LED. The
SKIM sends messages to the Instrument Cluster to
turn the LED on for about three seconds when the
ignition switch is turned to the ON position as a bulb
test. After completion of the bulb test, the SKIM
sends bus messages to keep the LED off for a duration of about one second. Then the SKIM sends messages to turn the LED on or off based upon the
results of the SKIS self-tests. If the VTSS indicator
LED comes on and stays on after the bulb test, it
indicates that the SKIM has detected a system malfunction and/or that the SKIS has become inoperative.
If the SKIM detects an invalid key when the ignition switch is turned to the ON position, it sends
messages to flash the VTSS indicator LED. The
SKIM can also send messages to flash the LED as an
indication to the customer that the SKIS has been
placed in it’s “Customer Learn” programming mode.
See Sentry Key Immobilizer System Transponder
Programming in this section for more information on
the “Customer Learn” programming mode.
For diagnosis or initialization of the SKIM and the
PCM, a DRBIIIt scan tool and the proper Powertrain
Diagnostic Procedures manual are required. The
SKIM cannot be repaired and, if faulty or damaged,
the unit must be replaced.
8E - 14 ELECTRONIC CONTROL MODULES DR
SENTRY KEY IMMOBILIZER MODULE (Continued)
STANDARD PROCEDURE - PCM/SKIM
PROGRAMMING
NOTE: There are two procedures for transfering the
secret key to the SKIM:
• When ONLY the SKIM module is replaced, the
secret key is transfered from the PCM to the SKIM.
The ORGINAL KEYS may then be programmed to
the SKIM.
• When ONLY the PCM is replaced, then the
secret key is transfered from the SKIM to the PCM.
The ORGINAL KEYS may be used.
• When BOTH the SKIM and the PCM are
replaced the secret key is transferred from the
SKIM to the PCM, and NEW KEYS must be programmed.
NOTE: Before replacing the Powertrain Control
Module (PCM) 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 PCM 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 Diagnostic Trouble
Code (DTC) has set.
When a PCM (SBEC) and the Sentry Key Immobilizer Module (SKIM) are replaced at the same time
perform the following steps in order:
(1) Program the new PCM (SBEC).
(2) Program the new SKIM.
(3) Replace all ignition keys and program them to
the new SKIM.
PROGRAMMING THE PCM (SBEC)
The Sentry Key Immobilizer System (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 DRBIIIt scan tool. 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 DRBIIIt scan tool 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 monitor the 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, MISCELLANEOUS, and
SRI MEMORY CHECK.
(8) The DRBIIIt scan tool will ask, Is odometer
reading between XX and XX? Select the YES or NO
button on the DRB IIIt scan tool. If NO is selected,
the DRBIIIt scan tool will read, Enter odometer
Reading<From I.P. odometer>. Enter the odometer
reading from the instrument cluster and press
ENTER.
PROGRAMMING THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIIt scan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select SKIM 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 the
SKIM, the SKIM must be replaced.
(6) Select YES to update the 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 information to the
SKIM).
(8) Program ignition keys to the 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 DRBIIIt scan tool 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.
DR ELECTRONIC CONTROL MODULES 8E - 15
SENTRY KEY IMMOBILIZER MODULE (Continued)
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.
(5) If ignition key programming is unsuccessful,
the DRBIIIt scan tool will display one of the following messages:
(a) Programming Not Attempted - The DRBIIIt
scan tool attempts to read the programmed key
status and there are no keys programmed into
SKIM memory.
(b) Programming Key Failed (Possible Used Key
From Wrong Vehicle) - SKIM is unable to program
key due to one of the following:
• Faulty ignition key transponder.
• Ignition key is programmed to another vehicle.
(c) 8 Keys Already Learned, Programming Not
Done - SKIM transponder ID memory is full.
(6) Obtain ignition keys to be programmed from
customer (8 keys maximum).
(7) Using the DRBIIIt scan tool, erase all ignition
keys by selecting MISCELLANEOUS and ERASE
ALL CURRENT IGN. KEYS.
(8) Program all ignition keys.
Learned Key In Ignition - Ignition key transponder
ID is currently programmed in SKIM memory.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the steering column upper and lower
shrouds. Refer to Steering, Column, Shroud,
Removal.
(3) Disconnect the steering column wire harness
connector from the Sentry Key Immobilizer Module
(SKIM)
(4) Remove the screw securing the SKIM module
to the steering column (Fig. 8).
(5) Release the SKIM antenna ring retaining clips
from around the ignition switch lock cylinder housing
and remove the SKIM.
INSTALLATION
NOTE: If the SKIM is replaced with a new unit, a
DRBIIIT scan tool MUST be used to initialize the
new SKIM and to program at least two Sentry Key
transponders. (Refer to 8 - ELECTRICAL/VEHICLE
THEFT SECURITY - STANDARD PROCEDURE).
Fig. 8 SENTRY KEY IMMOBILIZER MODULE (SKIM)
1 - SENTRY KEY IMMOBILIZER MODULE (SKIM)
2 - STEERING COLUMN
3 - SCREW
4 - WIRING HARNES
(4) Install the steering column upper and lower
shrouds. Refer to Steering, Column, Shroud, Installation.
(5) Connect the battery negative cable.
TRANSFER CASE CONTROL
MODULE
DESCRIPTION
The Transfer Case Control Module (TCCM) (Fig. 9)
is a microprocessor-based assembly, controlling the
4X4 transfer case shift functions via the actuation of
a shift motor and utilizing the feedback of a mode
sensor assembly. Communication is via the PCI serial
bus. Inputs include user selectable 4X4 modes that
include 2WD, 4HI, 4LO, and Neutral. The logic and
driver circuitry is contained in a molded plastic housing with an embedded heat-sink and is located
behind the left side of the lower instrument panel.
OPERATION
(1) Slide the SKIM antenna ring around the ignition switch lock cylinder housing and clip in place
(Fig. 8).
(2) Install the retaining screw.
(3) Connect the steering column wire harness connector to the Sentry Key Immobilizer Module
(SKIM).
The Transfer Case Control Module (TCCM) utilizes
the input from the transfer case mounted mode sensor, the instrument panel mounted selector switch,
and the following information from the vehicle’s PCI
serial bus to determine if a shift is allowed.
• Engine RPM and Vehicle Speed
8E - 16 ELECTRONIC CONTROL MODULES DR
TRANSFER CASE CONTROL MODULE (Continued)
module must receive one ignition message that
denotes that the ignition is in the RUN position.
• Sleep Mode will be entered, from the Reduced
Power Mode, when no PCI traffic has been sensed for
20 ±1 seconds. If during Sleep Mode the module
detects PCI bus traffic, it will revert to the Reduced
Power mode while monitoring for ignition messages.
It will remain in this state as long as there is traffic
other than run or start messages, and will return to
Sleep mode if the bus goes without traffic for 20 ±1
seconds.
SHIFT REQUIREMENTS
If the TCCM is in full power mode and at functionality level zero, it uses the following criteria to determine if a shift is allowed.
Fig. 9 Transfer Case Control Module (TCCM)
Location
1 - INSTRUMENT PANEL
2 - TRANSFER CASE CONTROL MODULE (TCCM)
3 - TRANSFER CASE SELECTOR SWITCH
• Diagnostic Requests
• Manual Transmission and Brake Applied
• PRNDL
• Ignition Status
• ABS Messages
Once the TCCM determines that a requested shift
is allowed, it actuates the bi-directional shift motor
as necessary to achieve the desired transfer case
operating mode. The TCCM also monitors the mode
sensor while controlling the shift motor to determine
the status of the shift attempt.
Several items can cause the requested shift not to
be completed. If the TCCM has recognized a fault
(DTC) of some variety, it will begin operation in one
of four Functionality Levels. These levels are:
• Level Zero - Normal Operation.
• Level One - Only Mode Shifts Are Allowed.
• Level Two - Only Mode Shifts and Shifts Into
LOW Are Allowed (No Neutral Shifts Are Allowed).
• Level Three - No Shifts Are Allowed
The TCCM can also be operating in one of three
possible power modes. These power modes are:
• Full Power Mode is the normal operational
mode of the module. This mode is achieved by normal
PCI bus traffic being present and the ignition being
in the RUN position.
• Reduced Power Mode will be entered when
the ignition has been powered off. In this state, the
module will shut down power supplied to external
devices, and to electronic interface inputs and outputs. From this state the module can enter either
Sleep Mode or Full Power Mode. To enter this mode,
the module must receive an ignition message denoting that the ignition is off, or not receive any messages for 5 ±0.5 seconds. To exit this mode, the
If any of the driver controllable conditions are not
met once the shift request is recognized, the TCCM
will solidly illuminate the source position’s LED and
flash the desired position’s LED for all shifts except
NEUTRAL. The NEUTRAL shift LED strategy will
be discussed later.
Mode shifts will be allowed regardless of transmission gear or vehicle speed, whenever the following
conditions are met:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
• A change in the Selector switch state indicates
that a mode shift has been requested.
• A valid mode sensor signal is being sensed by
the TCCM.
• Proper transmit/receive messages are occurring
on the PCI bus.
• Ignition key switch is in the RUN position.
Range shifts will be allowed only if all of the following conditions are met:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
• A change in the Selector Switch state indicating
a range shift has been requested.
• Transmission in NEUTRAL signal must be recognized for at least 1.5 seconds ±100 msec. (Automatic transmissions only)
• Proper transmit/receive messages are occurring
on the PCI bus.
• Clutch signal is recognized for 500 msec ± 50
msec (Manual transmissions only).
• Vehicle speed is less than or equal to 4.8 km/hr
(3 miles per hour).
• Ignition key switch is in the RUN position.
• A valid mode sensor signal is being sensed by
the TCCM.
A shift into transfer case Neutral will be
allowed only if all of the following conditions are met:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
DR ELECTRONIC CONTROL MODULES 8E - 17
TRANSFER CASE CONTROL MODULE (Continued)
• The recessed Neutral Selection switch has been
depressed continuously for 4.0 seconds ±100 msec
while all shift conditions have been continuously met.
• Transmission in NEUTRAL signal recognized
from the bus. (Automatic transmissions only)
• Clutch signal is recognized from the bus (Manual transmissions only).
• Proper message transmissions/receptions are
occurring on the PCI bus.
• Vehicle speed is less than or equal to 4.8 km/hr
(3 miles per hour).
• Ignition key switch is in the RUN position,
engine off.
• Foot Brake is applied.
• A valid mode sensor signal is being sensed by
the TCCM.
A shift out of transfer case Neutral will be
allowed only if all of the following conditions are met:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
• The recessed Neutral Selection switch has been
depressed continuously for 1.0 seconds ±100 msec
while all shift conditions have been continuously met.
• Transmission in NEUTRAL signal recognized
from the bus.(Automatic transmissions only)
• Clutch signal is recognized from the bus (Manual transmissions only).
• Proper message transmissions/receptions are
occurring on the PCI bus.
• Vehicle speed is less than or equal to 4.8 km/hr
(3 miles per hour).
• Ignition key switch is in the RUN position.
• Foot Brake is applied.
• A valid mode sensor signal is being sensed by
the TCCM.
SHIFT SEQUENCES
Once all the driver controllable conditions for the
requested shift have been met, the TCCM begins a
shift timer with a maximum duration of 1 second per
’D’ channel transition. If the shift timer expires
before the TCCM recognizes to correct mode sensor
code, the shift is considered to have been blocked.
The blocked shift will increment the blocked shift
counter by one. The TCCM strategy for handling
blocked shifts will be described later. The process the
TCCM performs for the various shifts will be
described first.
RANGE AND MODE SHIFTS
The process for performing all the range and mode
shifts are the same. The following steps describe the
process.
• Allow time for Selector Switch debounce; 250
msec ±50 msec.
• Extinguish the source gear’s LED while flashing
desired transfer case position’s LED.
• Engage the shift motor for a maximum of 1 second ±100 msec per ’D’ channel transition in the destination gear’s direction while monitoring the mode
sensor channel transitions.
• Disengage the shift motor when the correct
mode sensor code is recognized.
• Solidly illuminate the selected gear’s LED.
• Transmit a bus message that the transfer case
shift is complete.
• If the desired mode sensor code is not received
after the shift timer expires (ie. a blocked or other
condition exists), stop driving the motor and wait for
200 msec ±50 msec. The shift motor is then reversed
in the direction back toward the source gear for up to
1.0 seconds ±100 msec. per ’D’ channel. The TCCM
waits for 2.0 seconds ±50 msec. and repeats the
attempt to shift to the desired position.
The exception to the preceding sequence is when a
shift from 4L to 2WD/AWD is requested. If 2WD/
AWD is requested from the 4L position, the transfer
case is first driven to the 4H position. If the 4H position is reached, the transfer case is then driven back
to the 2WD/AWD position and the shift is considered
complete. If the transfer case does not reach any the
4H position, but is in the 2WD/AWD ’D’ channel, or
the 2WD/AWD between gear position on the 4H side
of 2WD/AWD, the shift is also considered complete.
SHIFT OUT OF NEUTRAL
• Extinguish the Neutral LED.
• Engage the shift motor for a maximum of 1 sec-
ond ±100 msec toward the transfer case 4H mode
position while monitoring the mode sensor channel
transitions.
• Disengage the shift motor when the correct
mode sensor code is recognized.
• Extinguish the Neutral LED.
• Transmit a bus message that the transfer case
shift is complete.
• If the desired mode sensor code is not received
after the shift timer expires (ie. a blocked or other
condition exists), stop driving the motor and wait for
200 msec ±50 msec. The shift motor is then reversed
in the direction back toward the source gear for up to
1.0 seconds 100 msec. The TCCM waits for 2.0 seconds ±50 msec. and repeats the attempt to shift to
the desired position.
• When the Neutral button is released, if the 4H
position is the desired position, the shift is complete.
Illuminate the 4H LED.
• Otherwise when the Neutral button is released,
if all of the shift requirements are being met then
engage the shift motor towards the desired position
for 1 second ±100 msec per ’D’ channel. (if require-
8E - 18 ELECTRONIC CONTROL MODULES DR
TRANSFER CASE CONTROL MODULE (Continued)
ments for shifting are not met, illuminate the 4H
LED and flash the destination LED as an indication
to the driver that all of the driver controllable shift
conditions are not being met). If this requires
another range or mode shift, begin the range/mode
shift process.
• If the desired mode sensor code is not received
after the shift timer expires (i.e. a blocked or other
condition exists), refer to the section on Blocked Shift
Strategy.
BLOCKED SHIFT STRATEGY
When a shift is commanded, the shift motor will be
driven towards its destination position, except in the
case of shifting out of Neutral if 4L was selected (the
transfer case will shift to the 4H position first, before
proceeding to 4L). If the shift is blocked on the way
to the destination, the TCCM may attempt to drive
the motor back to the original position. This process
will be allowed to occur 5 times. If the transfer case
has reached a non-NEUTRAL ’D’ channel during the
shift re-attempts, the LED for the achieved gear position is illuminated and the shift attempts are
stopped. To re-attempt the desired shift, the selector
switch will need to be rotated to the current position
until the switch debounce timer expires then a shift
will need to be requested again.
At the end of the 5th blocked attempt, the shift
motor is driven towards the last known ’D’ channel
position. If this motor drive allows the transfer case
to reach the 2WD/AWD ’D’ channel, or the 2WD/AWD
between gear position on the 4H side of 2WD/AWD,
the shift is considered complete and the shift
attempts are ended.
If the mode sensor is in the NEUTRAL region at
the expiration of the shift timer, the TCCM will continue to make the shift attempts according to the
blocked shift strategy independent of whether or not
the driver controlled conditions are met.
For shifts from NEUTRAL, if all 5 attempts fail to
reach the desired position (which by default is 4H),
the motor will be driven to stall in the direction of
4H or 4L, depending on the achieved position. If the
transfer case has reached the 2WD/AWD or 4L
between gear position nearest the NEUTRAL positions and the shift conditions are no longer being
met, the transfer case will be driven toward the corresponding ’D’ channel. Otherwise, the transfer case
will be driven in the direction opposite the last
attempt with the desired target being 4H or 4L.
If the transfer case reaches the 2WD/AWD ’D’
channel when being driven in the 4H direction, then
one final 1.0 second drive toward 4H is attempted. If
the transfer case then reaches any of the 4H positions, the shift is considered complete and the 4H
LED is illuminated. If the transfer case is still the
2WD/AWD position, the shift is considered complete
and the 2WD/AWD LED is illuminated.
NOTE: If after the 5th blocked shift and reversal
attempt, if the transfer case position is in the NEUTRAL region, shift attempts will continue until a
non-NEUTRAL ’D’ channel is reached.
SHIFT REVERSAL TARGETS
If the shift timer expires (1 second per ’D’ channel)
and the transfer case has not reached the desired
position, all shifts will attempt to return to their
original position with the exceptions of:
• If the intended shift is going to the High rail
from Low and can’t make it, but it can make the
2WD/AWD position, the motor stops at that position.
The TCCM will not attempt to cross back over NEUTRAL if it does not have to. This means that there
was a block on the first attempt to go to 4H and the
transfer case has made it through NEUTRAL to a
known good position, then the motor will go back
only to the 2WD/4WD position and execute the
remainder of the attempts from there.
• For shifts out of NEUTRAL, any time a shift is
commanded out of NEUTRAL, the system needs to
get out. The TCCM should never go to NEUTRAL
unless the driver is commanding it and all required
conditions are being met
ENCODER DRIFT CORRECTION
Whenever a shift is completed, the TCCM stores
the position in memory as the transfer case’s
intended position. The TCCM continuously monitors
the mode sensor and if the mode sensor drifts toward
into a NEUTRAL region sensor position for 2.0 seconds, the TCCM will perform a motor drive to correct
the drift. The transfer case will be driven toward the
intended position for 1.0 seconds 100 msec. The
TCCM will wait for 2.0 seconds ±50 msec. and repeat
the attempt to shift to the desired position. This will
continue until the intended position is reached.
SHIFT MOTOR BRAKING
Two modes of shift motor braking are employed to
improve shift performance, static and dynamic. Static
shift motor braking is utilized under the following
conditions:
• Whenever the transfer case is in the 2WD/AWD
or 4L ’D’ channel position.
• Whenever an invalid mode sensor code is
present.
Static motor braking is achieved by applying +12V
on both shift motor wires.
NOTE: Static Shift Motor Braking is independent of
ignition key position.
DR ELECTRONIC CONTROL MODULES 8E - 19
TRANSFER CASE CONTROL MODULE (Continued)
SHIFT ATTEMPT LIMIT
To protect the transfer case system, the TCCM will
impose a limit on the number of shifts that can occur
over a calibrated time period. The system will monitor
the number of ’D’ channel segment transitions that
occur in any 30 second time period. If the number of
segment transitions is 30 or greater, the system will go
into a default mode. The default mode of operation for
shifting is that the number of allowed ’D’ channel transitions permitted to occur will be 3 over each 15 second
±100 msec calibrated window of time. After 5 minutes
±100 msec, the motor can be assumed to have cooled
down and the system will revert to normal operation.
The following rules also apply to the shift limit:
• The attempt limit will not prevent shifts coming
out of NEUTRAL, they will be allowed regardless of
the counter/timer.
• Any shift that is in progress when the counter
reaches a maximum count in time will be allowed to
complete before the default mode is entered. D-channel transitions during this period will not be counted
towards the default mode limit.
• A block, regardless of the direction, whether
towards destination or back towards reversal target
(shift timer expiring), will count as a value of 2 transitions towards the 30 segment transitions to go into
default mode as defined above. Current attempt limit
values are 30 transitions in 30 seconds and default
mode values are 3 transitions every 15 seconds for 5
minutes.
TRANSMISSION CONTROL
MODULE
DESCRIPTION
The Transmission Control Module (TCM) (Fig. 10)
may be sub-module within the Powertrain Control
Module (PCM) or a standalone module, depending on
the vehicle engine. The PCM, and TCM when
equipped, is located at the right rear of the engine
compartment, near the right inner fender.
OPERATION
The Transmission Control Module (TCM) controls
all electronic operations of the transmission. The
TCM receives information regarding vehicle operation from both direct and indirect inputs, and selects
the operational mode of the transmission. Direct
inputs are hardwired to, and used specifically by the
TCM. Indirect inputs are shared with the TCM via
the vehicle communication bus.
Some examples of direct inputs to the TCM are:
• Battery (B+) voltage
• Ignition “ON” voltage
• Transmission Control Relay (Switched B+)
1 - RIGHT FENDER
2 - TRANSMISSION CONTROL MODULE
3 - POWERTRAIN CONTROL MODULE
• Throttle Position Sensor
• Crankshaft Position Sensor
• Transmission Range Sensor
• Pressure Switches
• Transmission Temperature Sensor
• Input Shaft Speed Sensor
• Output Shaft Speed Sensor
• Line Pressure Sensor
Some examples of indirect inputs to the TCM are:
• Engine/Body Identification
• Manifold Pressure
• Target Idle
• Torque Reduction Confirmation
• Engine Coolant Temperature
• Ambient/Battery Temperature
• DRBIIIt Scan Tool Communication
Based on the information received from these various inputs, the TCM determines the appropriate
shift schedule and shift points, depending on the
present operating conditions and driver demand.
This is possible through the control of various direct
and indirect outputs.
Some examples of TCM direct outputs are:
• Transmission Control Relay
• Solenoids
• Torque Reduction Request
Some examples of TCM indirect outputs are:
• Transmission Temperature (to PCM)
• PRNDL Position (to BCM)
In addition to monitoring inputs and controlling
outputs, the TCM has other important responsibilities and functions:
• Storing and maintaining Clutch Volume Indexes
(CVI)
Storing and selecting appropriate Shift Schedules
•
• System self-diagnostics
• Diagnostic capabilities (with DRBIIIt scan tool)
Fig. 10 PCM/TCM Location
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