AIR INTAKE JEEP LIBERTY 2002 KJ / 1.G Workshop Manual

(5) Align the marks front and rear at the cam/
pivot bolts and tighten the bolts. Tighten the bolts to
170 N´m (125 ft.lbs.)
(6) Install the stabilizer link bolt at the lower con-
trol arm. Tighten the bolt to 136 N´m (100 ft.lbs.)
(7) Install the lower clevis bracket bolt at the
lower control arm. Tighten the bolt to 150 N´m (110
ft.lbs.)
(8) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
(9) Perform a full wheel alignment (Refer to 2 -
SUSPENSION/WHEEL ALIGNMENT - STANDARD
PROCEDURE).
SHOCK
REMOVAL
REMOVAL - LEFT SIDE
(1) Disconnect the battery.
(2) Remove the battery (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - REMOVAL).
(3) Unclip the power center and move it to the side
out of the way.
(4) Remove the battery tray (Refer to 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - REMOVAL).
(5) Disconnect the battery temperature sensor
from the battery tray.
(6) Remove the four upper shock mounting nuts.
(7) Raise and support the vehicle.(8) Remove the left tire and wheel assembly.
(9) Remove the lower bolt at the lower control
securing the clevis bracket.
(10) Remove the stabilizer link (Refer to 2 - SUS-
PENSION/FRONT/STABILIZER LINK - REMOVAL).
(11) Remove the lower ball joint nut.
(12) Seperate the lower ball joint from the lower
control arm using tool C-4150A.
(13) Rotate the lower control arm downward to
allow access.
(14) Remove the clevis bracket at the shock.
(15) Remove the shock assembly from the vehicle.
(Fig. 4)
(16) Remove the spring from the shock (if needed).
REMOVAL - RIGHT SIDE
(1) Remove the air box (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
REMOVAL).
(2) Remove the two cruise control servo mounting
nuts.
(3) Remove the upper shock mounting nuts.
(4) Raise and support the vehicle.
(5) Remove the right side tire assembly.
(6) Remove the lower bolt at the lower control
securing the clevis bracket.
(7) Remove the stabilizer link (Refer to 2 - SUS-
PENSION/FRONT/STABILIZER LINK - REMOVAL).
(8) Remove the lower ball joint nut.
(9) Seperate the lower ball joint from the lower
control arm using tool C-4150A.
(10) Rotate the lower control arm downward to
allow access.
Fig. 3 LOWER CONTROL ARM
1 - FRONT CAM BOLT
2 - OUTER TIE ROD END
3 - LOWER BALL JOINT NUT
4 - LOWER CONTROL ARM
5 - REAR CAM BOLT
Fig. 4 SHOCK ASSEMBLY
1 - SPRING
2 - JOUNCE BUMPER
3 - SHOCK
4 - UPPER CONTROL ARM
KJFRONT 2 - 11
LOWER CONTROL ARM (Continued)

(11) Remove the clevis bracket at the shock. (Fig.
5)
(12) Remove the shock assembly from the vehicle.
(Fig. 5)
(13) Remove the spring from the shock (if needed).
(Refer to 2 - SUSPENSION/FRONT/SPRING -
REMOVAL).
INSTALLATION
INSTALLATION - LEFT SIDE
(1) Install the spring to the shock (if removed).
(2) Install the shock assembly to the vehicle.
(3) Install the four upper shock mounting nuts.
Tighten the nuts to 108 N´m (80 ft.lbs.).
(4) Install the clevis bracket at the shock. (Refer to
2 - SUSPENSION/FRONT/CLEVIS BRACKET -
INSTALLATION). Tighten the bolt to 88 N´m (65
ft.lbs.).
(5) Raise the lower control into place and recon-
nect the lower ball joint nut. Tighten the nut to 81
N´m (60 ft.lbs.).
(6) Install the clevis bracket at the lower control
arm. (Refer to 2 - SUSPENSION/FRONT/CLEVIS
BRACKET - INSTALLATION). Tighten the bolt to
150 N´m (110 ft.lbs.).(7) Install the lower stabilizer link at the lower
control arm. Tighten the bolt to 136 N´m (100 ft.lbs.)
(Refer to 2 - SUSPENSION/FRONT/STABILIZER
LINK - INSTALLATION).
(8) Install the left tire and wheel assembly. (Refer
to 22 - TIRES/WHEELS/WHEELS - STANDARD
PROCEDURE).
(9) Lower the vehicle.
(10) Reconnect the battery temperature sensor.
(11) Install the battery tray (Refer to 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - INSTALLA-
TION).
(12) Install the battery (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - INSTALLA-
TION).
(13) Reconnect the battery cables.
INSTALLATION - RIGHT SIDE
(1) Install the spring to the shock (if removed).
(Refer to 2 - SUSPENSION/FRONT/SPRING -
INSTALLATION).
(2) Install the shock assembly to the vehicle.
(3) Install the four upper shock mounting nuts.
Tighten the nuts to 108 N´m (80 ft.lbs.).
(4) Install the clevis bracket at the shock. (Refer to
2 - SUSPENSION/FRONT/CLEVIS BRACKET -
INSTALLATION). Tighten the bolt to 88 N´m (65
ft.lbs.).
(5) Raise the lower control into place and recon-
nect the lower ball joint nut. Tighten the nut to 81
N´m (60 ft.lbs.).
(6) Install the clevis bracket at the lower control
arm. (Refer to 2 - SUSPENSION/FRONT/CLEVIS
BRACKET - INSTALLATION). Tighten the bolt to
150 N´m (110 ft.lbs.).
(7) Install the lower stabilizer link at the lower
control arm. Tighten the bolt to 136 N´m (100 ft.lbs.)
(Refer to 2 - SUSPENSION/FRONT/STABILIZER
LINK - INSTALLATION).
(8) Install the right tire and wheel assembly.
(Refer to 22 - TIRES/WHEELS/WHEELS - STAN-
DARD PROCEDURE).
(9) Lower the vehicle.
(10) Install the cruise control servo mounting nuts.
(11) Install the airbox (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
INSTALLATION).
Fig. 5 SHOCK & CLEVIS ASSEMBLY
1 - FRONT CRADLE
2 - SPRING & SHOCK ASSEMBLY
3 - STEERING KNUCKLE
4 - CLEVIS BRACKET
5 - LOWER CONTROL ARM
2 - 12 FRONTKJ
SHOCK (Continued)

STABILIZER BAR
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the tire and wheel assembly.
(3) Remove the upper stabilizer link bolts at the
stabilizer bar.
(4) Remove the stabilizer bar bushing clamps from
the frame (Fig. 8).
(5) Remove the stabilizer bar from the vehicle.
INSTALLATION
(1) Install the stabilizer bar to the vehicle.
(2) Install the stabilizer bar bushing clamps (Fig.
8). Tighten the nuts to 149 N´m (110 ft.lbs.).
(3) Install the upper stabilizer link bolts and
washer at the stabilizer bar. Tighten the bolt to 136
N´m (100 ft.lbs.).
(4) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
(5) Lower the vehicle.
STABILIZER LINK
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the tire and wheel assembly.
(3) Remove the lower stabilizer link bolt at the
lower control arm.
(4) Remove the upper stabilizer link bolt at the
stabilizer bar.
(5) Remove the stabilizer link. (Fig. 9)
INSTALLATION
(1) Install the stabilizer link (Fig. 9).
(2) Install the upper stabilizer link bolt and
washer at the stabilizer bar. Tighten the bolt to 136
N´m (100 ft.lbs.).
(3) Install the lower stabilizer link bolt and
washer at the lower control arm. Tighten the nut to
115 N´m (85 ft.lbs.).
(4) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
UPPER CONTROL ARM
REMOVAL
REMOVAL - RIGHT SIDE
(1) Raise and support the vehicle.
(2) Remove the right side tire and wheel assembly.
(3) Remove the upper ball joint nut.
(4) Separate the upper ball joint from the steering
knuckle using tool C-4150A.
(5) Lower the vehicle.
(6) Remove the air box (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
REMOVAL).
(7) Remove the cruise control servo mounting nuts.
(8) Remove the upper control arm rear bolt.
(9) Remove the upper control arm front bolt.
(10) Remove the upper control arm from the vehi-
cle.
Fig. 8 SWAY BAR
1-SWAYBAR
2 - SWAY BAR BUSHINGS
Fig. 9 STABILIZER BAR LINK
1 - STABILIZER BAR
2 - STABILIZER BAR LINK
2 - 14 FRONTKJ

REMOVAL - LEFT SIDE
(1) Raise and support the vehicle.
(2) Remove the left side tire and wheel assembly.
(3) Remove the upper ball joint nut.
(4) Separate the upper ball joint from the steering
knuckle using tool C-4150A.
(5) Lower the vehicle.
(6) Remove the battery (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - REMOVAL).
(7) Unclip the power center and move it to the side
out of the way.
(8) Remove the battery tray (Refer to 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - REMOVAL).
(9) Disconnect the battery temperature sensor
from the battery tray.
(10) Remove the upper control arm rear bolt by
using a ratchet and extension under the steering
shaft and positioned by the power steering reservoir.
(Fig. 10)
(11) Remove the upper control arm front bolt.
(12) Remove the upper control arm from the vehi-
cle.
INSTALLATION
INSTALLATION - RIGHT SIDE
(1) Install the upper control arm to the vehicle.
(2) Install the upper control arm front bolt.
Tighten the bolt to 122 N´m (90 ft.lbs.).
(3) Install the upper control arm rear bolt. Tighten
the bolt to 122 N´m (90 ft.lbs.).
(4) Install the cruise control servo mounting nuts.(5) Install the air box (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
INSTALLATION).
(6) Install the upper ball joint nut. Tighten the nut
to 81 N´m (60 ft.lbs.).
(7) Install the right side tire and wheel assembly.
(Refer to 22 - TIRES/WHEELS/WHEELS - STAN-
DARD PROCEDURE).
(8) Lower the vehicle.
(9) Set the toe and center the steering wheel
(Refer to 2 - SUSPENSION/WHEEL ALIGNMENT -
STANDARD PROCEDURE).
INSTALLATION - LEFT SIDE
(1) Install the upper control arm to the vehicle.
(2) Install the upper control arm front bolt (Fig.
11). Tighten the bolt to 122 N´m (90 ft.lbs.).
(3) Install the upper control arm rear bolt (Fig.
11). Tighten the bolt to 122 N´m (90 ft.lbs.).
(4) Reconnect the battery temperature sensor to
the battery tray.
(5) Install the battery tray (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/TRAY - INSTALLATION).
(6) Install the battery (Refer to 8 - ELECTRICAL/
BATTERY SYSTEM/BATTERY - INSTALLATION).
(7) Reclip and mount the power center.
(8) Install the upper ball joint nut (Fig. 11).
Tighten the nut to 81 N´m (60 ft.lbs.).
(9) Install the left side tire and wheel assembly.
(Refer to 22 - TIRES/WHEELS/WHEELS - STAN-
DARD PROCEDURE).
(10) Lower the vehicle.
(11) Set the toe and center the steering wheel
(Refer to 2 - SUSPENSION/WHEEL ALIGNMENT -
STANDARD PROCEDURE).
Fig. 10 REAR BOLT
1 - STEERING SHAFT
2 - REAR BOLT
3 - RATCHET WITH AN EXTENSION
Fig. 11 UPPER CONTROL ARM
KJFRONT 2 - 15
UPPER CONTROL ARM (Continued)

POWER BRAKE BOOSTER
DESCRIPTION
The booster assembly consists of a housing divided
into separate chambers by two internal diaphragms.
The outer edge of each diaphragm is attached to the
booster housing. The diaphragms are connected to
the booster primary push rod.
Two push rods are used in the booster. The pri-
mary push rod connects the booster to the brake
pedal. The secondary push rod connects the booster
to the master cylinder to stroke the cylinder pistons.
OPERATION
The atmospheric inlet valve is opened and closed
by the primary push rod. Booster vacuum supply is
through a hose attached to an intake manifold fitting
at one end and to the booster check valve at the
other. The vacuum check valve in the booster housing
is a one-way device that prevents vacuum leak back.
Power assist is generated by utilizing the pressure
differential between normal atmospheric pressure
and a vacuum. The vacuum needed for booster oper-
ation is taken directly from the engine intake mani-
fold. The entry point for atmospheric pressure is
through a filter and inlet valve at the rear of the
housing (Fig. 33).
The chamber areas forward of the booster dia-
phragms are exposed to vacuum from the intake
manifold. The chamber areas to the rear of the dia-
phragms, are exposed to normal atmospheric pres-
sure of 101.3 kilopascals (14.7 pounds/square in.).Brake pedal application causes the primary push
rod to open the atmospheric inlet valve. This exposes
the area behind the diaphragms to atmospheric pres-
sure. The resulting pressure differential provides the
extra apply force for power assist.
The booster check valve, check valve grommet and
booster seals are serviceable.
DIAGNOSIS AND TESTING - MASTER
CYLINDER/POWER BOOSTER
(1) Start engine and check booster vacuum hose
connections. A hissing noise indicates vacuum leak.
Correct any vacuum leak before proceeding.
(2) Stop engine and shift transmission into Neu-
tral.
(3) Pump brake pedal until all vacuum reserve in
booster is depleted.
(4) Press and hold brake pedal under light foot
pressure. The pedal should hold firm, if the pedal
falls away master cylinder is faulty (internal leak-
age).
(5) Start engine and note pedal action. It should
fall away slightly under light foot pressure then hold
firm. If no pedal action is discernible, power booster,
vacuum supply, or vacuum check valve is faulty. Pro-
ceed to the POWER BOOSTER VACUUM TEST.
(6) If the POWER BOOSTER VACUUM TEST
passes, rebuild booster vacuum reserve as follows:
Release brake pedal. Increase engine speed to 1500
rpm, close the throttle and immediately turn off igni-
tion to stop engine.
(7) Wait a minimum of 90 seconds and try brake
action again. Booster should provide two or more vac-
uum assisted pedal applications. If vacuum assist is
not provided, booster is faulty.
POWER BOOSTER VACUUM TEST
(1) Connect vacuum gauge to booster check valve
with short length of hose and T-fitting (Fig. 34).
(2) Start and run engine at curb idle speed for one
minute.
(3) Observe the vacuum supply. If vacuum supply
is not adequate, repair vacuum supply.
(4) Clamp hose shut between vacuum source and
check valve.
(5) Stop engine and observe vacuum gauge.
(6) If vacuum drops more than one inch Hg (33
millibars) within 15 seconds, booster diaphragm or
check valve is faulty.
POWER BOOSTER CHECK VALVE TEST
(1) Disconnect vacuum hose from check valve.
(2) Remove check valve and valve seal from
booster.
(3) Use a hand operated vacuum pump for test.
Fig. 32 BOOSTER PUSH ROD
1 - MASTER CYLINDER ASSEMBLY
2 - BRAKE BOOSTER
3 - CLIP
4 - BRAKE PEDAL
5 - BOOSTER ROD
KJBRAKES - BASE 5 - 21
PEDAL (Continued)

(2) Attach bleed tubes to cylinder outlet ports.
Then position each tube end into reservoir (Fig. 40).
(3) Fill reservoir with fresh brake fluid.
(4) Press cylinder pistons inward with wood dowel.
Then release pistons and allow them to return underspring pressure. Continue bleeding operations until
air bubbles are no longer visible in fluid.
REMOVAL
(1) Siphon and drain the fluid from the reservoir.
(2) Remove the brake lines at the master cylinder.
(3) Disconnect the fluid level electrical connector
from the reservoir.
(4) Remove mounting nuts from the master cylin-
der.
(5) Remove master cylinder.
(6) Remove cylinder cover and drain the rest of the
fluid.
(7) If master cylinder reservoir requires service-
,(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
FLUID RESERVOIR - REMOVAL). (Fig. 41)
INSTALLATION
NOTE: If master cylinder is replaced, bleed cylinder
before installation.
(1) Clean cylinder mounting surface of brake
booster.
(2) Install master cylinder onto brake booster
studs.
(3) Install mounting nuts and tighten to 25 N´m
(220 in. lbs.).
(4) Connect the brake lines to the master cylinder
and tighten to 20 N´m (180 in. lbs.).
(5) Connect fluid level electrical connector to the
reservoir.
(6) Fill and bleed base brake system,(Refer to 5 -
BRAKES - STANDARD PROCEDURE).
Fig. 38 Typical Booster Vacuum Test Connections
1 - TEE FITTING
2 - SHORT CONNECTING HOSE
3 - CHECK VALVE
4 - CHECK VALVE HOSE
5 - CLAMP TOOL
6 - INTAKE MANIFOLD
7 - VACUUM GAUGE
Fig. 39 TYPICAL - VACUUM CHECK VALVE AND
SEAL
1 - BOOSTER CHECK VALVE
2 - APPLY TEST VACUUM HERE
3 - VALVE SEAL
Fig. 40 MASTER - TYPICAL
1 - BLEEDING TUBES
2 - RESERVOIR
KJBRAKES - BASE 5 - 25
MASTER CYLINDER (Continued)

BRAKES
TABLE OF CONTENTS
page page
POWER BRAKE BOOSTER
REMOVAL - RHD........................1INSTALLATION - RHD.....................1
POWER BRAKE BOOSTER
REMOVAL - RHD
(1) Remove the air box (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
REMOVAL).
(2) Relocate the cruise control servo to gain access
to the booster for removal.
(3) Remove the brake lines from the master cylin-
der.
(4) Remove the master cylinder (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/MASTER
CYLINDER - REMOVAL).
(5) Disconnect vacuum hose from booster check
valve.
(6) Remove knee blocker under the steering colum-
n,(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER - REMOVAL).
(7) Remove the brake light switch.(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
BRAKE LAMP SWITCH - REMOVAL)
(8) Remove retaining clip that secures booster
push rod to brake pedal (Fig. 1).
(9) Remove nuts attaching booster to the dash
panel (Fig. 2).(10) In engine compartment, slide booster studs
out of dash panel, tilt booster upward, and remove
booster from engine compartment.
INSTALLATION - RHD
(1) Align and position booster on the dash panel.
(2) Install booster mounting nuts. Tighten nuts
just enough to hold booster in place.
(3) Slide booster push rod onto the brake pedal.
Then secure push rod to pedal pin with retaining
clip.
NOTE: Lubricate the pedal pin with Mopar multi-
mileage grease before installation.
(4) Tighten booster mounting nuts to 39 N´m (29
ft. lbs.).
(5) Install the brake light switch.
(6) Install the knee blocker,(Refer to 23 - BODY/
INSTRUMENT PANEL/KNEE BLOCKER - INSTAL-
LATION).
(7) If original master cylinder is being installed,
check condition of seal at rear of master cylinder.
Replace seal if cut, or torn.
(8) Clean cylinder mounting surface of brake
booster. Use shop towel wetted with brake cleaner for
Fig. 1 BOOSTER PUSH ROD
1 - BRAKE PEDAL
2 - BOOSTER ROD
Fig. 2 BOOSTER MOUNTING
1 - BRAKE BOOSTER
KJBRAKES 5s - 1

BRAKES
TABLE OF CONTENTS
page page
POWER BRAKE BOOSTER
REMOVAL - RHD........................1INSTALLATION - RHD.....................1
POWER BRAKE BOOSTER
REMOVAL - RHD
(1) Remove the air box (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
REMOVAL).
(2) Relocate the cruise control servo to gain access
to the booster for removal.
(3) Remove the brake lines from the master cylin-
der.
(4) Remove the master cylinder (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/MASTER
CYLINDER - REMOVAL).
(5) Disconnect vacuum hose from booster check
valve.
(6) Remove knee blocker under the steering colum-
n,(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER - REMOVAL).
(7) Remove the brake light switch.(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
BRAKE LAMP SWITCH - REMOVAL)
(8) Remove retaining clip that secures booster
push rod to brake pedal (Fig. 1).
(9) Remove nuts attaching booster to the dash
panel (Fig. 2).(10) In engine compartment, slide booster studs
out of dash panel, tilt booster upward, and remove
booster from engine compartment.
INSTALLATION - RHD
(1) Align and position booster on the dash panel.
(2) Install booster mounting nuts. Tighten nuts
just enough to hold booster in place.
(3) Slide booster push rod onto the brake pedal.
Then secure push rod to pedal pin with retaining
clip.
NOTE: Lubricate the pedal pin with Mopar multi-
mileage grease before installation.
(4) Tighten booster mounting nuts to 39 N´m (29
ft. lbs.).
(5) Install the brake light switch.
(6) Install the knee blocker,(Refer to 23 - BODY/
INSTRUMENT PANEL/KNEE BLOCKER - INSTAL-
LATION).
(7) If original master cylinder is being installed,
check condition of seal at rear of master cylinder.
Replace seal if cut, or torn.
(8) Clean cylinder mounting surface of brake
booster. Use shop towel wetted with brake cleaner for
Fig. 1 BOOSTER PUSH ROD
1 - BRAKE PEDAL
2 - BOOSTER ROD
Fig. 2 BOOSTER MOUNTING
1 - BRAKE BOOSTER
KJBRAKES 5s - 1

The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resis-
tance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).
When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer air-
fuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
²for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
²Injector pulse-width
²Spark-advance curves
²ASD relay shut-down times
²Idle Air Control (IAC) motor key-on steps
²Pulse-width prime-shot during cranking
²O2 sensor closed loop times
²Purge solenoid on/off times
²EGR solenoid on/off times (if equipped)
²Leak Detection Pump operation (if equipped)
²Radiator fan relay on/off times (if equipped)
²Target idle speed
REMOVAL
2.4L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at left front of cylinder
head (Fig. 1).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Partially drain cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from cylinder head.
3.7L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at front of intake mani-
fold near rear of generator (Fig. 2).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.(1) Partially drain cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from intake manifold.
Fig. 1 ECT AND UPPER TIMING BELT COVER/
BOLTS-2.4L
1 - UPPER TIMING BELT COVER
2 - ELECTRICAL CONNECTOR (ECT)
3 - MOUNTING BOLTS (3)
Fig. 2 MAP SENSOR / ECT SENSOR - 3.7L
1 - MOUNTING SCREWS
2 - MAP SENSOR
3 - ECT SENSOR
7 - 20 ENGINEKJ
ENGINE COOLANT TEMPERATURE SENSOR (Continued)

ENGINE COOLANT
TEMPERATURE SENSOR
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is
used to sense engine coolant temperature. The sensor
protrudes into an engine water jacket.
The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resis-
tance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).
When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer air-
fuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
²for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
²Injector pulse-width²Spark-advance curves
²ASD relay shut-down times
²Idle Air Control (IAC) motor key-on steps
²Pulse-width prime-shot during cranking
²O2 sensor closed loop times
²Purge solenoid on/off times
²EGR solenoid on/off times (if equipped)
²Leak Detection Pump operation (if equipped)
²Radiator fan relay on/off times (if equipped)
²Target idle speed
REMOVAL
2.4L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at left front of cylinder
head (Fig. 2).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Partially drain cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from cylinder head.
3.7L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at front of intake mani-
fold near rear of generator (Fig. 3).
Fig. 1 ENGINE BLOCK HEATER 2.4L
1 - CORE HOLE
2 - BLOCK HEATER
3 - POWER CORD
Fig. 2 ECT AND UPPER TIMING BELT COVER/
BOLTS-2.4L
1 - UPPER TIMING BELT COVER
2 - ELECTRICAL CONNECTOR (ECT)
3 - MOUNTING BOLTS (3)
KJENGINE7s-21
ENGINE BLOCK HEATER - 2.4L (Continued)