BOOST PRESSURE SENSOR
The Boost Pressure Sensor is mounted to the top of
the intake manifold. (Fig. 2) It is a sensor that mea-
sures both manifold vacuum and turbo boost, and it
also contains an integrated intake air temperature
sensor. The Boost Pressure Sensor takes the place of
the Mass Air Flow (MAF). In the Intake Air Temper-
ature Sensor component, there is a ceramic element
that changes its resistance based on temperature.
The ceramic element is part of an electronic circuit
connected to the PCM, and has a voltage applied to
it. The ceramic element is exposed to the air inside
the intake. This air has a cooling effect on the
ceramic element, and its resistance changes. This
causes the voltage flowing through the intake air
temperature circuit to vary. The voltage signal pro-
duced by the Intake Air Temperature Sensor changes
inversely to the temperature, and is measured by the
PCM. As a general rule, when the temperature of the
air in the intake is high, the voltage signal produced
by the Intake Air Temperature Sensor is low. The
component of the Boost Pressure Sensor that mea-
sures manifold vacuum and turbo boost produces a
voltage signal that is proportional to the pressure in
the inake manifold. When the intake manifold pres-
sure is low, the voltage is low, and when the pressure
is high, the voltage is high. The PCM uses the volt-
age signals from the Boost Pressure Sensor, and the
Intake Air Temperature Sensor to determine the
amount of air flowing through the intake manifold.
VEHICLE THEFT ALARM
The PCM can learn if the vehicle has a Vehicle
Theft Alarm (VTA) system. Once it detects the vehi-
cle having VTA,the controller can ONLY BE
USED ON VEHICLES WITH VTA.If the PCM is put it on a vehicle without VTA the
Glow Plug Lamp will start to blink and the vehicle
will not start.
The PCM cannot be flashed to remove the VTA.
BATTERY VOLTAGEÐPCM INPUT
The battery voltage input provides power to the
PCM. It also informs the PCM what voltage level is
being supplied by the generator once the vehicle is
running.
The battery input also provides the voltage that is
needed to keep the PCM memory alive. The memory
stores Diagnostic Trouble Code (DTC) messages.
Trouble codes will still be stored even if the battary
voltage is lost.
SENSOR RETURNÐPCM INPUT (ANALOG
GROUND)
Sensor Return provides a low noise Analog ground
reference for all system sensors.
SIGNAL GROUNDÐPCM INPUT
Signal ground provides a low noise ground to the
data link connector.
IGNITION CIRCUIT SENSEÐPCM INPUT
The ignition circuit sense input signals the PCM
that the ignition (key) switch has been turned to the
ON position. This signal initiates the glow plug con-
trol routine to begin the ªpre±heatº cycle.
START SIGNALÐPCM INPUT
This input tells the PCM that the engine starter is
being operated. This in turn will start the glow plug
ªpost±heatº cycle.
POWER GROUND
Provides a common ground for power devices (sole-
noid and relay devices).
NEEDLE MOVEMENT OR INSTRUMENTED FIRST
INJECTORÐPCM INPUT
This input from the PCM supplies a constant 30
mA electrical current source for the first injector sen-
sor. It will vary the voltage to this sensor when it
senses a mechanical movement within the injector
needle (pintle) of the number±1 cylinder fuel injector.
When this voltage has been determined by the PCM,
it will then control an output to the fuel timing sole-
noid (the fuel timing solenoid is located on the fuel
injection pump). Also refer to Fuel Injection Pump for
additional information.
The first injector sensor is a magnetic (inductive)
type.
Fig. 2 Boost Pressure Sensor Location
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 45
DESCRIPTION AND OPERATION (Continued)
The speed sensor generates 8 pulses per sensor
revolution. These signals, in conjunction with a
closed throttle signal from the throttle position sen-
sor, indicate a closed throttle deceleration to the
PCM. When the vehicle is stopped at idle, a closed
throttle signal is received by the PCM (but a speed
sensor signal is not received).
In addition to determining distance and vehicle
speed, the output from the sensor is used to control
speed control operation.
SPEED CONTROLÐPCM INPUTS
The speed control system provides five separate
inputs to the PCM; On/Off, Set, Resume/Accel, Cancel,
and Decel.. The On/Off input informs the PCM that
the speed control system has been activated. The Set
input informs the PCM that a fixed vehicle speed has
been selected. The Resume input indicates to the PCM
that the previous fixed speed is requested.
Speed control operation will start at 50 km/h±142
km/h (35±85 mph). The upper range of operation is
not restricted by vehicle speed. Inputs that affect
speed control operation are vehicle speed sensor and
throttle position sensor.
Refer to Group 8H for further speed control infor-
mation.
DIESEL PCM RELAYÐPCM INPUT
A 12 volt signal at this input indicates to the PCM
that the Diesel relay has been activated. The Diesel
relay is located in the PDC. The PDC is located next
to the battery in the engine compartment. For the
location of the relay within the PDC, refer to label on
PDC cover.
This input is used only to sense that the Diesel
relay is energized. If the PCM does not see 12 volts +
at this input when the Diesel relay should be acti-
vated, it will set a Diagnostic Trouble Code (DTC).
FIVE VOLT POWERÐPCM OUTPUT
This circuit supplies approximately 5 volts to
power the Accelerator Pedal Postion Sensor, Mass Air
Flow Sensor, and A/C Pressure Sensor.
ENGINE COOLANT GAUGEÐPCM OUTPUT
Refer to the Instrument Panel and Gauges group
for additional information.
ENGINE OIL PRESSURE GAUGEÐPCM OUTPUT
Refer to the Instrument Panel and Gauges group
for additional information.
GLOW PLUG LAMPÐPCM OUTPUT
The Glow Plug lamp (malfunction indicator lamp)
illuminates on the message center each time the igni-
tion (key) switch is turned on. It will stay on for
about two seconds as a bulb test.If the PCM receives an incorrect signal, or no sig-
nal from certain sensors or components, the lamp
BLINKS. This is a warning that the PCM has
recorded a system or sensor malfunction. It signals
an immediate need for service. There are only 5
HARD faults that can turn on this lamp to make it
blink.
SPEED CONTROLÐPCM OUTPUTS
These two circuits control the fuel quantity actua-
tor to regulate vehicle speed. Refer to Group 8H for
Speed Control information.
AIR CONDITIONING RELAYÐPCM OUTPUT
This circuit controls a ground signal for operation
of the A/C clutch relay. Also refer to Air Conditioning
(A/C) ControlsÐPCM Input for additional informa-
tion.
The A/C relay is located in the Power Distribution
Center (PDC). The PDC is located next to the battery
in the engine compartment. For the location of the
relay within the PDC, refer to label on PDC cover.
FUEL TIMING SOLENOIDÐPCM OUTPUT
The fuel timing solenoid is located on the bottom of
the fuel injection pump (Fig. 10).
This 12+ volt, pulse width modulated (duty±cycle)
output controls the amount of fuel timing (advance)
in the fuel injection pump. The higher the duty-
Fig. 9 Glow Plug Lamp Symbol
Fig. 10 Fuel Timing Solenoid
14 - 48 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
DESCRIPTION AND OPERATION (Continued)
In this chart, Pre±Heat and Post±Heat times are
mentioned. Pre±heat is the amount of time the glow
plug relay circuit is activated when the ignition (key)
switch is ON, but the engine has yet to be started.
Post±heat is the amount of time the glow plug relay
circuit is activated after the engine is operating. The
Glow Plug lamp will not be illuminated during the
post±heat cycle.
TESTING:
Disconnect and isolate the electrical connectors
(Fig. 16) at all four glow plugs. With the engine cool
or cold, and the key in the ON position, check for
10±12 volts + at each electrical connector. 10±12 volts
+ should be at each connector whenever the PCM is
operating in the pre±heat or post±heat cycles (refer
to the following Glow Plug Control chart).Be very
careful not to allow any of the four discon-
nected glow plug electrical connectors to con-
tact a metal surface. When the key is turned to
the ON position, approximately 100 amps at 12
volts is supplied to these connectors.If 10±12
volts + is not available at each connector, check con-
tinuity of wiring harness directly to the relay. If con-
tinuity is good directly to the relay, the fault is either
with the relay or the relay input from the PCM. To
test the relay only, refer to RelaysÐOperation/Test-
ing in this section of the group. If the relay test is
good, refer to the DRB scan tool.
Diagnostic Trouble Codes:Refer to On-Board
Diagnostics in Group 25, Emission Control System
for a list of Diagnostic Trouble Codes (DTC's) for cer-
tain fuel system components.
RELAYSÐOPERATION/TESTING
The following description of operation and
tests apply only to the Diesel PCM and other
relays. The terminals on the bottom of each relay
are numbered (Fig. 17).
OPERATION
²Terminal number 30 is connected to battery volt-
age. For both the Diesel and other relays, terminal
30 is connected to battery voltage at all times.
²The PCM grounds the coil side of the relay
through terminal number 85.
²Terminal number 86 supplies voltage to the coil
side of the relay.
²When the PCM de-energizes the Diesel PCM
and other relays, terminal number 87A connects to
terminal 30. This is the Off position. In the off posi-
tion, voltage is not supplied to the rest of the circuit.
Terminal 87A is the center terminal on the relay.
Fig. 15 Glow Plug Relay Location
Fig. 16 Wiring Connection at Glow Plug
GLOW PLUG CONTROL
14 - 52 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
DIAGNOSIS AND TESTING (Continued)
(2) Remove the sensor mounting bolts.
(3) Remove the sensor.
INSTALLATION
(1) Install the sensor flush against the opening in
the transmission housing.
(2) Install and tighten the sensor mounting bolt to
19 N´m (14 ft. lbs.) torque.
(3) Connect the electrical connector to the sensor.
ENGINE COOLANT TEMPERATURE SENSOR
The sensor is located on the side of cylinder head
near the rear of fuel injection pump (Fig. 19).
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
REFER TO GROUP 7, COOLING.
(1) Partially drain cooling system. Refer to Group
7, Cooling.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from cylinder head.
INSTALLATION
(1) Install a new copper gasket to sensor.
(2) Install sensor to cylinder head.
(3) Tighten sensor to 18 N´m (13 ft. lbs.) torque.
(4) Connect electrical connector to sensor.
(5) Replace any lost engine coolant. Refer to Group
7, Cooling System.
GLOW PLUGS
The glow plugs are located above each fuel injector
(Fig. 20). Four individual plugs are used.
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) Clean the area around the glow plug with com-
pressed air before removal.
(3) Disconnect electrical connector (Fig. 21) at glow
plug.
(4) Remove the glow plug (Fig. 20) from cylinder
head.
Fig. 18 Engine Speed SensorFig. 19 Engine Coolant Temperature Sensor
Location
Fig. 20 Glow Plug
14 - 54 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
REMOVAL AND INSTALLATION (Continued)
INSTALLATION
(1) Apply high±temperature anti±seize compound
to glow plug threads before installation
(2) Install the glow plug into the cylinder head.
Tighten to 23 N´m (203 in. lbs.) torque.
(3) Connect battery cable to battery.
GLOW PLUG RELAY
The glow plug relay is located in the engine com-
partment on the left±inner fender (Fig. 22).
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) Remove relay mounting bolt.(3) Disconnect electrical connector at relay and
remove relay.
INSTALLATION
(1) Check condition of electrical connector for dam-
age or corrosion. Repair as necessary.
(2) Install electrical connector to relay.
(3) Install relay to inner fender.
(4) Connect battery cable to battery.
POWERTRAIN CONTROL MODULE (PCM)
The PCM is mounted to a bracket located in the
center consule in front of the air bag module (Fig.
23).
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) Loosen the 68±Way connector (Fig. 23). The
electrical connector has a sliding bar which moves
inward to lock or outward to unlock.
(3) Remove the electrical connector by pulling
straight out.
(4) Remove PCM.
INSTALLATION
(1) After the PCM electrical connector has been
separated from the PCM, inspect the pins for corro-
sion, being spread apart, bent or misaligned. Also
inspect the pin heights in the connector. If the pin
heights are different, this would indicate a pin has
separated from the connector. Repair as necessary.
(2) Engage 68±way connector into PCM. Move
slide bar to lock connector.
(3) Connect negative cable to battery.
VEHICLE SPEED SENSOR
The vehicle speed sensor (Fig. 24) is located on the
extension housing of the transmission.
Fig. 21 Glow Plug Electrical Connector
Fig. 22 Glow Plug Relay Location
Fig. 23 PCM Location
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 55
REMOVAL AND INSTALLATION (Continued)
DIAGNOSIS AND TESTING
STEERING COLUMN
For diagnosis of conditions relating to the steering
column, refer to the steering system diagnosis charts,
in the diagnosis and testing section at the beginning
of this group.
SERVICE PROCEDURES
STEERING COLUMN SERVICE PROCEDURE
WARNINGS
WARNING: BEFORE BEGINNING ANY SERVICE
PROCEDURES THAT INVOLVES REMOVING THE
AIR BAG. REMOVE AND ISOLATE THE NEGATIVE
(-) BATTERY CABLE (GROUND) FROM THE VEHI-
CLE BATTERY. THIS IS THE ONLY SURE WAY TO
DISABLE THE AIR BAG SYSTEM. FAILURE TO DO
THIS COULD RESULT IN ACCIDENTAL AIR BAG
DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
WARNING: THE AIR BAG SYSTEM IS A SENSITIVE,
COMPLEX ELECTRO-MECHANICAL UNIT. BEFORE
ATTEMPTING TO DIAGNOSE, REMOVE OR INSTALL
THE AIR BAG SYSTEM COMPONENTS YOU MUST
FIRST DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE. FAILURE TO DO SO
COULD RESULT IN ACCIDENTAL DEPLOYMENT OF
THE AIR BAG AND POSSIBLE PERSONAL INJURY.
THE FASTENERS, SCREWS, AND BOLTS, ORIGI-
NALLY USED FOR THE AIR BAG COMPONENTS,
HAVE SPECIAL COATINGS AND ARE SPECIFI-
CALLY DESIGNED FOR THE AIR BAG SYSTEM.
THEY MUST NEVER BE REPLACED WITH ANY SUB-
STITUTES. ANYTIME A NEW FASTENER IS
NEEDED, REPLACE WITH THE CORRECT FASTEN-
ERS PROVIDED IN THE SERVICE PACKAGE OR
FASTENERS LISTED IN THE PARTS BOOKS.
BEFORE SERVICING A STEERING COLUMN
EQUIPPED WITH AN AIR BAG, REFER TO GROUP
8M, ELECTRICAL FOR PROPER AND SAFE SER-
VICE PROCEDURES.
NOTE: Safety goggles should be worn at all times
when working on steering columns.
CAUTION: Disconnect negative (ground) cable
from the battery, before servicing any column com-
ponent.CAUTION: Do not attempt to remove the pivot pins
to disassemble the tilting mechanism. Damage will
occur.
REMOVAL AND INSTALLATION
STEERING COLUMN ASSEMBLY
To service the steering wheel and its components
or the air bag, refer to Group 8M, Restraint Systems.
Follow all WARNINGS.
To service the switches, refer to the appropriate
section of Group 8, Electrical.
To replace the steering column assembly, refer to
the steering column removal procedure.
REMOVE
(1) Make sure the front wheels of the vehicle are
in thestraight aheadposition before beginning the
column removal procedure.
(2) Disconnect negative (ground) cable from the
battery and isolate cable from battery terminal.
(3) Remove the screws attaching the lower steer-
ing column cover to the instrument panel (Fig. 2).
Remove the lower trim panel from the lower instru-
ment panel.
(4) Remove the park brake pedal release cable
from the park brake release lever (Fig. 3).
(5) Remove the 10 bolts attaching the steering col-
umn cover liner (Fig. 4) to the instrument panel.
Remove the steering column cover liner from the
lower instrument panel.
(6) Rotate key cylinder to the lock position and
remove key. Rotate the steering wheel a half turn to
the left until the steering column lock engages keep-
ing the steering column in the locked position (Fig.
5).
Fig. 2 Lower Steering Column Cover Attachment
Locations
19 - 38 STEERINGNS
Some water leaks must be tested for a considerable
length of time to become apparent. When a leak
appears, find the highest point of the water track or
drop. The highest point usually will show the point of
entry. After leak point has been found, repair the
leak and water test to verify that the leak has
stopped.
Locating the entry point of water that is leaking
into a cavity between panels can be difficult. The
trapped water may splash or run from the cavity,
often at a distance from the entry point. Most water
leaks of this type become apparent after accelerating,
stopping, turning, or when on an incline.
MIRROR INSPECTION METHOD
When a leak point area is visually obstructed, use
a suitable mirror to gain visual access. A mirror can
also be used to deflect light to a limited-access area
to assist in locating a leak point.
BRIGHT LIGHT LEAK TEST METHOD
Some water leaks in the luggage compartment can
be detected without water testing. Position the vehi-
cle in a brightly lit area. From inside the darkened
luggage compartment inspect around seals and body
seams. If necessary, have a helper direct a drop light
over the suspected leak areas around the luggage
compartment. If light is visible through a normally
sealed location, water could enter through the open-
ing.
PRESSURIZED LEAK TEST METHOD
When a water leak into the passenger compart-
ment cannot be detected by water testing, pressurize
the passenger compartment and soap test exterior of
the vehicle. To pressurize the passenger compart-
ment, close all doors and windows, start engine, and
set heater control to high blower in HEAT position. If
engine can not be started, connect a charger to the
battery to ensure adequate voltage to the blower.
With interior pressurized, apply dish detergent solu-
tion to suspected leak area on the exterior of the
vehicle. Apply detergent solution with spray device or
soft bristle brush. If soap bubbles occur at a body
seam, joint, seal or gasket, the leak entry point could
be at that location.
WIND NOISE
Wind noise is the result of most air leaks. Air leaks
can be caused by poor sealing, improper body compo-
nent alignment, body seam porosity, or missing plugs
in the engine compartment or door hinge pillar areas.
All body sealing points should be airtight in normal
driving conditions. Moving sealing surfaces will not
always seal airtight under all conditions. At times,
side glass or door seals will allow wind noise to be
noticed in the passenger compartment during highcrosswinds. Over compensating on door or glass
adjustments to stop wind noise that occurs under
severe conditions can cause premature seal wear and
excessive closing or latching effort. After a repair pro-
cedure has been performed, test vehicle to verify
noise has stopped before returning vehicle to use.
Wind noise can also be caused by improperly fitted
exterior moldings or body ornamentation. Loose
moldings can flutter, creating a buzzing or chattering
noise. An open cavity or protruding edge can create a
whistling or howling noise. Inspect the exterior of the
vehicle to verify that these conditions do not exist.
VISUAL INSPECTION BEFORE TESTS
Verify that floor and body plugs are in place and
body components are aligned and sealed. If component
alignment or sealing is necessary, refer to the appro-
priate section of this group for proper procedures.
ROAD TESTING WIND NOISE
(1) Drive the vehicle to verify the general location
of the wind noise.
(2) Apply 50 mm (2 in.) masking tape in 150 mm
(6 in.) lengths along weatherstrips, weld seams or
moldings. After each length is applied, drive the vehi-
cle. If noise goes away after a piece of tape is applied,
remove tape, locate, and repair defect.
POSSIBLE CAUSE OF WIND NOISE
²Moldings standing away from body surface can
catch wind and whistle.
²Gaps in sealed areas behind overhanging body
flanges can cause wind-rushing sounds.
²Misaligned movable components.
²Missing or improperly installed plugs in pillars.
²Weld burn through holes.
SERVICE PROCEDURES
HEAT STAKING
(1) Remove trim panel.
(2) Bend or move the trim panel components at
the heat staked joints. Observe the heat staked loca-
tions and/or component seams for looseness.
(3) Heat stake the components.
(a) If the heat staked or component seam loca-
tion is loose, hold the two components tightly
together and using a soldering gun with a flat tip,
melt the material securing the components
together. Do not over heat the affected area, dam-
age to the exterior of the trim panel may occur.
(b) If the heat staked material is broken or miss-
ing, use a hot glue gun to apply new material to
the area to be repaired. The panels that are being
heat staked must be held together while the apply-
ing the glue. Once the new material is in place, it
23 - 24 BODYNS
DIAGNOSIS AND TESTING (Continued)
(2) Remove liquid line at filter-drier (Fig. 42).
(3) Remove the (2) bolts holding filter-drier bracket
to radiator fan module bracket.
(4) Remove the lower liquid line at condenser.
(5) Remove the upper radiator crossmember.
(6) Pull up on radiator and slide filter-drier from
the mounting location.
INSTALLATION
(1) Before installation, replace both refrigerant
line O-rings. Then reverse the above procedures.
Torque filter/drier mounting bolts to 45 in. lbs.610.
(2) Evacuate and recharge system.
HEATER A/C UNIT HOUSING
REMOVAL
WARNING: IF EQUIPPED WITH AIR CONDITIONING,
THE REFRIGERATION SYSTEM MUST BE COM-
PLETELY EMPTY BEFORE PROCEEDING.
(1) Set parking brake.
(2) Disconnect battery negative cable.
(3) Using a refrigerant recovery machine, remove
refrigerant from the A/C system (Fig. 43).
(4) Remove wiper module. Refer to Group 8K,
Windshield Wipers and Washers.
(5) Pinch off rear heater lines if equipped.
(6) Drain engine coolant. Remove heater hoses at
the heater core (Fig. 44). Plug coolant lines.
(7) Remove suction and liquid lines at the expan-
sion valve (Fig. 45).(8) Remove the Instrument Panel Assembly. Refer
to Group 8E, Instrument Panel and Gauges.
(9) Remove heater ducts.
Fig. 42 Filter-Drier Assembly
Fig. 43 A/C Service Ports
Fig. 44 Heater Hoses
Fig. 45 Expansion Valve Plate
NSHEATING AND AIR CONDITIONING 24 - 29
REMOVAL AND INSTALLATION (Continued)