engine light JEEP LIBERTY 2002 KJ / 1.G Owner's Manual

CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC)1. During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly.1. A normal condition. No correction
is necessary.
2. Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.2. Check operation of gauge and
repair if necessary. Refer to Group
8J, Instrument cluster.
3. Gauge reading rises when
vehicle is brought to a stop after
heavy use (engine still running)3. A normal condition. No correction
is necessary. Gauge should return
to normal range after vehicle is
driven.
4. Gauge reading high after
re-starting a warmed up (hot)
engine.4. A normal condition. No correction
is necessary. The gauge should
return to normal range after a few
minutes of engine operation.
5. Coolant level low in cooling
system (air will build up in the
cooling system causing the
thermostat to open late).5. Check and correct coolant leaks.
(Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
6. Cylinder head gasket leaking
allowing exhaust gas to enter
cooling system causing a
thermostat to open late.6. (a) Check for cylinder head
gasket leaks. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING).
(b) Check for coolant in the engine
oil. Inspect for white steam emitting
from the exhaust system. Repair as
necessary.
7. Water pump impeller loose on
shaft.7. Check water pump and replace
as necessary. (Refer to 7 -
COOLING/ENGINE/WATER PUMP -
DIAGNOSIS AND TESTING).
8. Loose accessory drive belt.
(water pump slipping)8. (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS
- DIAGNOSIS AND TESTING).
Check and correct as necessary.
9. Air leak on the suction side of
the water pump allows air to build
up in cooling system causing
thermostat to open late.9. Locate leak and repair as
necessary.
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
TO COOLANT TANK.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK1. Pressure relief valve in pressure
bottle cap is defective.1. Check condition of radiator cap
and cap seals. (Refer to 7 -
COOLING/ENGINE/RADIATOR
PRESSURE CAP - DIAGNOSIS
AND TESTING). Replace cap as
necessary.
7s - 8 COOLING - 2.4LKJ
COOLING - 2.4L (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)

economy, and/or trip odometer data has been reset.
The CMTC uses internal programming, hard wired
inputs from the U.S./Metric and Reset switches, and
electronic messages received from the Body Control
Module (BCM) to determine the proper reset mes-
sages to send to the EMIC.
²Door Ajar Warning- The EMIC chime tone
generator will generate a single ªbong-likeº chime
tone when the ignition switch is in the On position,
and electronic messages are received over the PCI
data bus from the Body Control Module (BCM) indi-
cating that the status of any door ajar input has
changed from closed to not closed, and from the PCM
indicating that the vehicle is moving. The BCM uses
internal programming, and hard wired inputs from
the door ajar switches and the ignition switch to
determine the proper door ajar switch messages to
send to the EMIC. The PCM uses internal program-
ming and a hard wired vehicle speed pulse input
received from the BCM to determine the proper vehi-
cle distance messages to send to the EMIC.
²Electrical System Voltage Low or High
Warning- Each time the ignition switch is turned to
the On position, the EMIC chime tone generator will
generate a single ªbong-likeº chime tone the first
time an electronic message is received over the PCI
data bus from the PCM requesting ªChargingº indi-
cator illumination. This warning would indicate that
the monitored electrical system voltage is either too
low or too high. This warning will only occur once
during an ignition cycle. The PCM uses internal pro-
gramming and hard wired inputs from the electrical
and charging systems to determine the proper
ªChargingº indicator messages to send to the EMIC.
²Engine Coolant Temperature High Warning
- Each time the ignition switch is turned to the On
position, the EMIC chime tone generator will gener-
ate ªbong-likeº chime tones the first time an elec-
tronic message is received over the PCI data bus
from the PCM indicating that the engine coolant
temperature is too high. This chime will sound for
five consecutive single tones, unless an electronic
message is received from the PCM indicating that
the engine coolant temperature is not too high, or
unless the ignition switch is turned to the Off posi-
tion before the five single tones have completed. The
PCM uses internal programming and a hard wired
input from the engine coolant temperature sensor to
determine the proper engine coolant temperature
messages to send to the EMIC.
²Engine Oil Pressure Low Warning- Each
time the ignition switch is turned to the On position,
the EMIC chime tone generator will generate a sin-
gle ªbong-likeº chime tone the first time three
sequential sets of electronic messages are received
over the PCI data bus from the PCM indicating thatthe engine oil pressure is too low with the engine
running. The PCM uses internal programming and
hard wired inputs from the oil pressure sensor and
the crankshaft position sensor to determine the
proper oil pressure and engine speed messages to
send to the EMIC.
²Fasten Seat Belt Warning- Each time the
ignition switch is turned to the On position, the
EMIC chime tone generator will generate repetitive
ªbong-likeº chime tones at a slow rate the first time
an electronic message is received over the PCI data
bus from the ACM requesting ªSeatbeltº indicator
illumination. The ACM uses internal programming
and hard wired inputs from the driver side front seat
belt switch and the ignition switch to determine that
the driver side front seat belt is not fastened with
the ignition switch in the On position. These chimes
will continue to sound for a duration of about six sec-
onds each time the ignition switch is turned to the
On position, or until the driver side front seat belt is
fastened, whichever occurs first. This audible warn-
ing occurs independent of the visual warning pro-
vided by the EMIC ªSeatbeltº indicator.
²Gate Ajar Warning- The EMIC chime tone
generator will generate a single ªbong-likeº chime
tone when the ignition switch is in the On position,
and electronic messages are received over the PCI
data bus from the BCM indicating that the status of
the tailgate ajar input has changed from closed to
not closed, and from the PCM indicating that the
vehicle is moving. The BCM uses internal program-
ming, and hard wired inputs from the tailgate ajar
switch and the ignition switch to determine the
proper tailgate ajar switch messages to send to the
EMIC. The PCM uses internal programming and a
hard wired vehicle speed pulse input received from
the BCM to determine the proper vehicle distance
messages to send to the EMIC.
²Glass Ajar Warning- The EMIC chime tone
generator will generate a single ªbong-likeº chime
tone when the ignition switch is in the On position,
and electronic messages are received over the PCI
data bus from the BCM indicating that the status of
the rear flip-up glass ajar input has changed from
closed to not closed, and from the PCM indicating
that the vehicle is moving. The BCM uses internal
programming, and hard wired inputs from the flip-up
glass ajar switch and the ignition switch to deter-
mine the proper flip-up glass ajar switch messages to
send to the EMIC. The PCM uses internal program-
ming and a hard wired vehicle speed pulse input
received from the BCM to determine the proper vehi-
cle distance messages to send to the EMIC.
²Head/Park/Fog Lights-On Warning- The
EMIC chime tone generator will generate repetitive
ªbong-likeº chime tones at a fast rate when the igni-
KJCHIME/BUZZER 8B - 3
CHIME WARNING SYSTEM (Continued)

tion switch is in any position except On, and elec-
tronic messages are received over the PCI data bus
from the BCM indicating that the exterior lights are
On with the ignition switch in any position except
On, and the status of the driver side front door is not
closed. The BCM uses internal programming and
hard wired inputs from the left (lighting) control
stalk of the multi-function switch, the ignition
switch, and the driver side front door ajar switch to
determine the proper messages to send to the EMIC.
These chimes will continue to sound until the exte-
rior lighting is turned Off, until the ignition switch is
turned to the On position, or until the status of the
driver side front door ajar input changes from not
closed to closed, whichever occurs first.
²Key-In-Ignition Warning- The EMIC chime
tone generator will generate repetitive ªbong-likeº
chime tones at a fast rate when the ignition switch is
in any position except On, and electronic messages
are received over the PCI data bus from the BCM
indicating that the key is in the ignition lock cylinder
with the ignition switch in any position except On,
and the driver side front door is not closed. The BCM
internal programming and hard wired inputs from
the key-in ignition circuitry of the ignition switch,
the ignition switch, and the driver side front door
ajar switch to determine the proper messages to send
to the EMIC. These chimes will continue to sound
until the key is removed from the ignition lock cylin-
der, until the ignition switch is turned to the On
position, or until the status of the driver side front
door ajar input changes from not closed to closed,
whichever occurs first.
²Low Coolant Warning- On vehicles equipped
with a diesel engine, the EMIC chime tone generator
will generate a single ªbong-likeº chime tone when
the ignition switch is first turned to the On position
and a hard wired input from the engine coolant level
sensor to the EMIC indicates that the coolant level is
low for more than about one-quarter second. Any
time after the ignition switch is first turned to the
On position, the EMIC uses internal programming to
check the status of the engine coolant level sensor
inputs about once every second, then adjusts an
internal counter up or down based upon the status of
this input. When the counter accumulates thirty
inputs indicating that the coolant level is low, a sin-
gle chime tone is sounded. This strategy is intended
to reduce the effect that coolant sloshing within the
coolant reservoir can have on reliable chime warning
operation. This warning will only occur once during
an ignition cycle.
²Low Fuel Warning- Each time the ignition
switch is turned to the On position, the EMIC chime
tone generator will generate a single ªbong-likeº
chime tone the first time an electronic message isreceived over the PCI data bus from the PCM
requesting ªLow Fuelº indicator illumination. The
chime will only occur a second time during the same
ignition cycle if another electronic message has been
received from the PCM indicating that there is an
increase in the fuel level equal to about 3 liters (0.8
gallon), then a subsequent electronic message from
the PCM requests ªLow Fuelº indicator illumination.
This strategy combined with filtering performed by
the internal programming of the PCM on the fuel
tank sending unit input is intended to reduce the
possibility of fuel sloshing within the fuel tank caus-
ing multiple low fuel warning chimes during a given
ignition cycle. The EMIC will also respond with the
low fuel warning chime when electronic fuel level
messages are received from the PCM indicating that
the hard wired input to the PCM from the fuel tank
sending unit is an open circuit (greater than full), or
a short circuit (less than empty).
²Low Washer Fluid Warning- The EMIC
chime tone generator will generate a single ªbong-
likeº chime tone when the ignition switch is turned
to the On position and a hard wired input from the
washer fluid level switch to the EMIC indicates the
washer fluid is low for more than about one-quarter
second. Any time after the ignition switch is first
turned to the On position, the EMIC uses internal
programming to check the status of the washer fluid
level switch inputs about once every second, then
adjusts an internal counter up or down based upon
the status of this input. When the counter accumu-
lates thirty inputs indicating that the washer fluid
level is low, a single chime tone is sounded. This
strategy is intended to reduce the effect that fluid
sloshing within the washer reservoir can have on
reliable chime warning operation. This warning will
only occur once during an ignition cycle.
²Overspeed Warning- The EMIC chime tone
generator will generate repetitive ªbong-likeº chime
tones at a slow rate when the ignition switch is in
the On position, and an electronic message received
over the PCI data bus from the PCM indicates that
the vehicle speed is over a programmed speed value.
The PCM uses internal programming and distance
pulse information received over a hard wired vehicle
speed pulse input from the BCM to determine the
proper vehicle speed messages to send to the EMIC.
The BCM uses an internally programmed electronic
pinion factor and a hard wired input from the rear
wheel speed sensor to calculate the proper distance
pulse information to send to the PCM. The electronic
pinion factor represents the proper tire size and axle
ratio information for the vehicle. These chimes will
continue to sound until the vehicle speed messages
are below the programmed speed value, or until the
ignition switch is turned to the Off position, which-
8B - 4 CHIME/BUZZERKJ
CHIME WARNING SYSTEM (Continued)

²RKE antenna (two circuits) - premium with
RKE only
²Tailgate ajar switch sense
²Tailgate cylinder lock switch sense
²Vehicle speed sensor
Refer to the appropriate wiring information for
additional details.
HARD WIRED OUTPUTS The hard wired outputs
of the BCM include the following:
²Courtesy lamp driver
²Courtesy lamp load shed
²Door lock relay control
²Driver door unlock relay control - premium
with RKE only
²Flip-up glass release motor driver
²Front fog lamp relay control - premium
with front fog lamps only
²Front wiper high/low relay control
²Front wiper on/off relay control
²Hazard lamp control
²High beam relay control
²Horn relay control - premium with RKE
only
²Instrument cluster wake up signal
²Low beam relay control
²Park lamp relay control
²Passenger door unlock relay control
²Rear fog lamp relay control - premium with
rear fog lamps in markets where required only
²Rear window defogger relay control
²RKE supply - premium with RKE only
²Tailgate lock driver
²Tailgate unlock driver
²Vehicle speed output
²Vehicle speed sensor supply
²VTSS indicator driver - premium with
VTSS only
Refer to the appropriate wiring information for
additional details.
GROUNDS The BCM receives ground through five
separate circuits, and also supplies a ground path to
several switches through the following hard wired
circuits:
²Ambient temperature sensor return
²Door lock switch ground
²Headlamp switch return
²Radio control mux return
²RKE ground - premium with RKE only
²Tailgate switch ground
Refer to the appropriate wiring information for
additional details.
COMMUNICATION Not including the two RKE
antenna circuits (RKE antenna + and ±), which
merely pass through the premium BCM from the
RKE module to the external RKE antenna in theinstrument panel wire harness, the BCM has the fol-
lowing communication circuits:
²PCI bus
²RKE program serial data - premium with
RKE only
²RKE transmit serial data - premium with
RKE only
Refer to the appropriate wiring information for
additional details.
MESSAGING The BCM uses the following mes-
sages received from other electronic modules over the
PCI data bus:
²Battery Temperature (PCM)
²Compass Mini-Trip Computer Button Sta-
tus (CMTC) - premium only
²Coolant Temperature (PCM)
²Distance Pulses (PCM)
²Engine Speed (PCM)
²Fuel Tank Level (PCM)
²Fuel Used (PCM)
²Intrusion Transceiver Module Commands
(ITM) - premium in markets where required
only
²Manifold Absolute Pressure (PCM)
²OK to Lock - Rolling Locks (PCM)
²SKIS Status (SKIM)
²Vehicle Identification Number (PCM)
²Vehicle Speed (PCM)
The BCM provides the following messages to other
electronic modules over the PCI data bus:
²A/C Select Switch Status (PCM)
²Country Code (EMIC, PCM, CMTC)
²Distance to Empty (CMTC) - premium only
²Door Ajar Status (EMIC)
²Exterior Lighting Status (EMIC)
²Flip-up Glass Ajar Status (EMIC)
²Fuel Economy (Average and Instantaneous)
(CMTC) - premium only
²Hood Ajar Status (ITM) - premium in mar-
kets where required only
²Ignition On Timer (CMTC) - premium only
²Intrusion Transceiver Module Commands
(ITM) - premium in markets where required
only
²Key-In Ignition Switch Status (EMIC)
²Outside Temperature (CMTC) - premium
only
²Panel Lamp Intensity (CMTC, Radio)
²Tailgate Ajar Status (EMIC)
²Radio Mode (Radio) - premium only
²Radio Preset Scan (Radio) - premium only
²Radio Seek Down (Radio) - premium only
²Radio Seek Up (Radio) - premium only
²Radio Volume Down (Radio) - premium
only
²Radio Volume Up (Radio) - premium only
8E - 6 ELECTRONIC CONTROL MODULESKJ
BODY CONTROL MODULE (Continued)

Schedule Condition Expected Operation
OverheatOil temperature above 240É F or
engine coolant temperature above
244É F- Delayed 2-3 upshift
- Delayed 3-4 upshift
- 3rd gear FEMCC from 30-48 mph
- 3rd gear PEMCC above 35 mph
- Above 25 mph the torque
converter will not unlock unless the
throttle is closed or if a wide open
throttle 2nd PEMCC to 1 kickdown
is made
STANDARD PROCEDURE - TCM QUICK LEARN
The quick learn procedure requires the use of the
DRBtscan tool.
This program allows the electronic transmission
system to recalibrate itself. This will provide the
proper transmission operation. The quick learn pro-
cedure should be performed if any of the following
procedures are performed:
²Transmission Assembly Replacement
²Transmission Control Module Replacement
²Solenoid Pack Replacement
²Clutch Plate and/or Seal Replacement
²Valve Body Replacement or Recondition
To perform the Quick Learn Procedure, the follow-
ing conditions must be met:
²The brakes must be applied
²The engine speed must be above 500 rpm
²The throttle angle (TPS) must be less than 3
degrees
²The shift lever position must stay in PARK until
prompted to shift to overdrive
²The shift lever position must stay in overdrive
after the Shift to Overdrive prompt until the DRBt
indicates the procedure is complete
²The calculated oil temperature must be above
60É and below 200É
HEATED SEAT MODULE
DESCRIPTION
The heated seat module is also known as the Seat
Heat Interface Module. The heated seat module (Fig.
14) is located under the left front seat cushion, where
it is secured to a mounting bracket via two push-pin
retainers. The heated seat module has a single con-
nector receptacle that allows the module to be con-
nected to all of the required inputs and outputs
through the seat wire harness.
The heated seat module is an electronic micropro-
cessor controlled device designed and programmed to
use inputs from the heated seat relay, the two heatedseat 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
Light-Emitting Diodes (LEDs) in each heated seat
switch. The heated seat module is also programmed
to perform self-diagnosis of certain heated seat sys-
tem 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 a fuse in the junction block.
The module is grounded at all times. 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 cur-
rent to the heated seat elements and sensors, and
Fig. 14 Heated Seat Module
1 - Mounting Tabs (Not Used On KJ)
2 - Heated Seat Module
3 - Connector Receptacle
KJELECTRONIC CONTROL MODULES 8E - 21
TRANSMISSION CONTROL MODULE (Continued)

nection at the starter solenoid B(+) terminal stud.
Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery positive cable.
(4) Connect the voltmeter to measure between the
battery negative cable terminal clamp and a good
clean ground on the engine block (Fig. 22). Rotate
and hold the ignition switch in the Start position.
Observe the voltmeter. If the reading is above 0.2
volt, clean and tighten the battery negative cable
eyelet terminal connection to the engine block.
Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery negative cable.THERMAL GUARD
DESCRIPTION
A flexible plastic bubble-wrap style thermal guard
(Fig. 23) slides over the battery case to enclose the
sides of the battery. The thermal guard consists of a
heavy black plastic outer skin and two lighter plies of
plastic that have been formed into a sheet with hun-
dreds of small air pockets entrapped between them.
The resulting material is very similar to the bubble-
wrap used to protect items in many parcel packaging
and shipping applications.
OPERATION
The thermal guard protects the battery from
engine compartment temperature extremes. The tem-
perature of the battery can affect battery perfor-
mance. The air trapped between the plastic plies of
the thermal guard create a dead air space, which
helps to insulate the sides of the battery case from
the air temperature found in the surrounding engine
compartment.
REMOVAL
(1) Remove the battery and the battery thermal
guard from the battery tray as a unit. Refer to Bat-
tery Removal for the proper battery removal proce-
dures.
(2) Carefully and evenly slide the battery thermal
guard up off of the battery case (Fig. 24).
INSTALLATION
(1) Clean and inspect the battery thermal guard.
Refer to Battery System Cleaning for the proper
cleaning procedures, and refer to Battery System
Inspection for the proper inspection procedures.
Fig. 21 TEST BATTERY POSITIVE CABLE
RESISTANCE - TYPICAL
1 - BATTERY
2 - VOLTMETER
3 - STARTER MOTOR
Fig. 22 TEST GROUND CIRCUIT RESISTANCE -
TYPICAL
1 - VOLTMETER
2 - BATTERY
3 - ENGINE GROUND
Fig. 23 Battery Thermal guard
1 - THERMAL GUARD
2 - BATTERY
8F - 20 BATTERY SYSTEMKJ
BATTERY CABLES (Continued)

3.7L
The Camshaft Position Sensor (CMP) on the 3.7L
V-6 engine is bolted to the front/top of the right cyl-
inder head.
(1) Clean out machined hole in cylinder head.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into cylinder head with a slight
rocking and twisting action.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder head.
If sensor is not flush, damage to sensor mounting
tang may result.
(4) Install mounting bolt and tighten. Refer to
torque specifications.
(5) Connect electrical connector to sensor.
IGNITION COIL
DESCRIPTION
2.4L
The coil assembly consists of 2 different coils
molded together. The assembly is mounted to the top
of the engine (Fig. 14).
3.7L
The 3.7L V-6 engine uses 6 dedicated, and individ-
ually fired coil for each spark plug (Fig. 15). Each
coil is mounted directly into the cylinder head and
onto the top of each spark plug (Fig. 16).
OPERATION
2.4L
The coil fires two spark plugs simultaneously. One
plug is under compression, the other plug fires on the
exhaust stroke (lost spark). Coil number one fires
Fig. 14 IGNITION COIL - 2.4L
1 - IGNITION COIL
2 - MOUNTING BOLTS (4)
Fig. 15 IGNITION COIL - 3.7L
1 - O-RING
2 - IGNITION COIL
3 - ELECTRICAL CONNECTOR
Fig. 16 IGNITION COIL LOCATION - 3.7L
1 - IGNITION COIL
2 - COIL MOUNTING NUT
KJIGNITION CONTROL 8I - 9
CAMSHAFT POSITION SENSOR (Continued)

cylinders 1 and 4, and coil number two fires cylinders
2 and 3.
The Auto Shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing the coil(s). The
PCM will de-energize the ASD relay if it does not
receive the crankshaft position sensor and camshaft
position sensor inputs.
Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Spark plug cables (secondary wires or cables) are
used with the 2.4L engine.
3.7L
Battery voltage is supplied to the 6 ignition coils
from the ASD relay. The Powertrain Control Module
(PCM) opens and closes each ignition coil ground cir-
cuit at a determined time for ignition coil operation.
Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Because of coil design, spark plug cables (second-
ary cables) are not used with the 3.7L engine.
REMOVAL
2.4L
(1) Disconnect electrical connector at rear of coil.
(2) Remove all secondary cables from coil.
(3) Remove 4 coil mounting bolts (Fig. 17).
(4) Remove coil from vehicle.
3.7L
An individual ignition coil is used for each spark
plug (Fig. 19). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 18). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.19) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector from coil by
pushing downward on release lock on top of connec-
tor and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
(4) Remove coil mounting nut from mounting stud
(Fig. 18).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
INSTALLATION
2.4L
(1) Position coil to engine.
(2) Install 4 mounting bolts. Refer to torque speci-
fications.
(3) Install secondary cables.
(4) Install electrical connector at rear of coil.
(5) Install air cleaner tube and housing.
3.7L
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
Fig. 17 IGNITION COIL - 2.4L
1 - IGNITION COIL
2 - MOUNTING BOLTS (4)
8I - 10 IGNITION CONTROLKJ
IGNITION COIL (Continued)

NOTE: Over or under tightening the sensor mount-
ing bolts will affect knock sensor performance, pos-
sibly causing improper spark control. Always use
the specified torque when installing the knock sen-
sors.
REMOVAL
The 2 knock sensors are bolted into the cylinder
block under the intake manifold (Fig. 20).
NOTE: The left sensor is identified by an identifica-
tion tag (LEFT). It is also identified by a larger bolt
head. The Powertrain Control Module (PCM) must
have and know the correct sensor left/right posi-
tions. Do not mix the sensor locations.
(1) Disconnect knock sensor dual pigtail harness
from engine wiring harness. this connection is made
near rear of left valve cover (Fig. 20).
(2) Remove intake manifold. Refer to Engine sec-
tion.
(3) Remove sensor mounting bolts (Fig. 20). Note
foam strip on bolt threads. This foam is used only to
retain the bolts to sensors for plant assembly. It is
not used as a sealant. Do not apply any adhesive,
sealant or thread locking compound to these bolts.
(4) Remove sensors from engine.
INSTALLATION
NOTE: The left sensor is identified by an identifica-
tion tag (LEFT). It is also identified by a larger bolt
head. The Powertrain Control Module (PCM) must
have and know the correct sensor left/right posi-
tions. Do not mix the sensor locations.
(1) Thoroughly clean knock sensor mounting holes.
(2) Install sensors into cylinder block.
NOTE: Over or under tightening the sensor mount-
ing bolts will affect knock sensor performance, pos-
sibly causing improper spark control. Always use
the specified torque when installing the knock sen-
sors. The torque for the knock senor bolt is rela-
tively light for an 8mm bolt.
NOTE: Note foam strip on bolt threads. This foam is
used only to retain the bolts to sensors for plant
assembly. It is not used as a sealant. Do not apply
any adhesive, sealant or thread locking compound
to these bolts.
(3) Install and tighten mounting bolts. Refer to
torque specification.
(4) Install intake manifold. Refer to Engine sec-
tion.
(5) Connect knock sensor wiring harness to engine
harness at rear of intake manifold.
SPARK PLUG
DESCRIPTION
Resistor type spark plugs are used.
Spark plug resistance values range from 6,000 to
20,000 ohms (when checked with at least a 1000 volt
spark plug tester).Do not use an ohmmeter to
check the resistance values of the spark plugs.
Inaccurate readings will result.
OPERATION
To prevent possible pre-ignition and/or mechanical
engine damage, the correct type/heat range/number
spark plug must be used.
Always use the recommended torque when tighten-
ing spark plugs. This is especially true when plugs
are equipped with tapered seats. Incorrect torque can
distort the spark plug and change plug gap. It can
also pull the plug threads and do possible damage to
both the spark plug and the cylinder head.
Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. A sin-
Fig. 20 KNOCK SENSOR LOCATION
1 - KNOCK SENSORS (2)
2 - MOUNTING BOLTS
8I - 12 IGNITION CONTROLKJ
KNOCK SENSOR (Continued)