NOTE: ECM Inputs:
²Accelerator Pedal Position Sensor (APPS) Volts
²APPS1 Signal Ð For off engine APPS
²APPS2 Signal Ð For off engine APPS
²APPS idle validation switches #1 and #2
²Battery Temperature
²Battery voltage
²Camshaft Position Sensor (CMP)
²CCD bus (+) circuits
²CCD bus (-) circuits
²Crankshaft Position Sensor (CKP)
²Data link connection for DRB scan tool
²Engine Coolant Temperature (ECT) sensor
²Fuel pressure sensor
²Fan speed (engine cooling fan)
²Ground circuits
²Inlet air temperature sensor/pressure sensor
²Intake air temperature sensor/MAP sensor
²Oil Pressure switch
²Power ground
²Sensor return
²Signal ground
²Water-In-Fuel (WIF) sensor
NOTE: ECM Outputs:
After inputs are received by the ECM, certain sen-
sors, switches and components are controlled or reg-
ulated by the ECM. These are consideredECM
Outputs.These outputs are for:
²CCD bus (+) circuits
²CCD bus (-) circuits
²CKP and APPS outputs to the PCM
²Data link connection for DRB scan tool
²Fan Clutch PWM
²Five volt sensor supply
²Fuel Control Actuator
²Fuel transfer (lift) pump
²Intake manifold air heater relays #1 and #2 con-
trol circuits
²Malfunction indicator lamp (Check engine lamp)
(databus)
²Oil Pressure Swith/warning lamp (databus)
²Wait-to-start warning lamp (databus)
²Water-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.To avoid possible voltage spike damage to the
ECM, ignition key must be off, and both negative
battery cables must be disconnected before unplug-
ging 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: The connector bolt is a
female allen head. As bolt is being removed, very
carefully remove connectors from the ECM.
(4) Remove five ECM mounting bolts and remove
ECM from the vehicle (Fig. 2).
INSTALLATION
Do not apply paint to ECM or a poor ground will
result.
(1) Position the ECM to the ECM support bracket
and install the five mounting bolts. Tighten the bolts
to 24 N´m (18 ft. lbs.).
(2) Check pin connectors in ECM, 50±way and
60±way connectors for corrosion or damage. Repair
as necessary.
(3) Clean pins in the 50±way and 60±way electri-
cal connectors with a electrical contact cleaner.
(4) Install the 50±way and 60±way connectors to
ECM. Tighten connector bolts to 3 N´m (27 in. lbs.).
(5) Reconnect both negative battery cables.
(6) Use DRBIIItscan tool to erase any stored com-
panion DTC's from ECM.
Fig. 2 Diesel ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
8E - 4 ELECTRONIC CONTROL MODULESDR
ENGINE CONTROL MODULE (Continued)
²Data link connection for DRB scan tool
²EATX module (if equipped)
²Engine coolant temperature sensor
²Fuel level (through J1850 circuitry)
²Generator (battery voltage) output
²Ignition circuit sense (ignition switch in on/off/
crank/run position)
²Intake manifold air temperature sensor
²Knock sensors (2 on 3.7L engine)
²Leak detection pump (switch) sense (if equipped)
²Manifold absolute pressure (MAP) sensor
²Oil pressure
²Oxygen sensors
²Park/neutral switch (auto. trans. only)
²Power ground
²Power steering pressure switch (if equipped)
²Sensor return
²Signal ground
²Speed control multiplexed single wire input
²Throttle position sensor
²Transfer case switch (4WD range position)
²Vehicle speed signal
NOTE: PCM Outputs:
²A/C clutch relay
²Auto shutdown (ASD) relay
²J1850 bus (+/-) circuits for: speedometer, voltme-
ter, fuel gauge, oil pressure gauge/lamp, engine temp.
gauge and speed control warn. lamp
²Data link connection for DRB scan tool
²EGR valve control solenoid (if equipped)
²EVAP canister purge solenoid
²Five volt sensor supply (primary)
²Five volt sensor supply (secondary)
²Fuel injectors
²Fuel pump relay
²Generator field driver (-)
²Generator field driver (+)
²Idle air control (IAC) motor
²Ignition coil(s)
²Leak detection pump (if equipped)
²Malfunction indicator lamp (Check engine lamp).
Driven through J1850 circuits.²Oxygen sensor heater relays
²Oxygen sensors (pulse width modulated)
²Radiator cooling fan relay (pulse width modu-
lated)
²Speed control vacuum solenoid
²Speed control vent solenoid
²Tachometer (if equipped). Driven through J1850
circuits.
²Transmission convertor clutch circuit. Driven
through J1850 circuits.
OPERATION - 5 VOLT SUPPLIES
Primary 5±volt supply:
²supplies the required 5 volt power source to the
Crankshaft Position (CKP) sensor.
²supplies the required 5 volt power source to the
Camshaft Position (CMP) sensor.
²supplies a reference voltage for the Manifold
Absolute Pressure (MAP) sensor.
²supplies a reference voltage for the Throttle
Position Sensor (TPS) sensor.
Secondary 5±volt supply:
²supplies the required 5 volt power source to the
oil pressure sensor.
²supplies the required 5 volt power source for the
Vehicle Speed Sensor (VSS) (if equipped).
²supplies the 5 volt power source to the transmis-
sion pressure sensor (certain automatic transmis-
sions).
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
the9ignition sense9circuit and is used to9wake 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 reg-
ulator and to allow the PCM to perform fuel, ignition
and emissions control functions.
DRELECTRONIC CONTROL MODULES 8E - 11
POWERTRAIN CONTROL MODULE (Continued)
TESTING
COLD CRANKING TEST
For complete starter wiring circuit diagrams, refer
to 8, Wiring Diagrams. The battery must be fully-
charged and load-tested before proceeding. Refer to
Batteryin 8, Battery.
(1) Connect volt-ampere tester to battery terminals
(Fig. 1). See instructions provided by manufacturer of
volt-ampere tester being used.Note: Certain diesel
equipped models use dual batteries. If equipped
with dual battery system, tester should be con-
nected to battery on left side of vehicle only.
Also, tester current reading must be taken from
positive battery cable lead that connects to
starter motor.
(2) Fully engage parking brake.
(3) If equipped with manual transmission, place
gearshift selector lever in Neutral position and block
clutch pedal in fully depressed position. If equipped
with automatic transmission, place gearshift selector
lever in Park position.
(4) Verify that all lamps and accessories are
turned off.
(5) To prevent a gasoline engine from starting,
remove Automatic ShutDown (ASD) relay. To prevent
a diesel engine from starting, remove Fuel Pump
Relay. These relays are located in Power Distribution
Center (PDC). Refer to label on PDC cover for relay
location.
WARNING: IF EQUIPPED WITH DIESEL ENGINE,
ATTEMPT TO START ENGINE A FEW TIMES
BEFORE PROCEEDING WITH FOLLOWING STEP.(6) Rotate and hold ignition switch in Start posi-
tion. Note cranking voltage and current (amperage)
draw readings shown on volt-ampere tester.
(a) If voltage reads below 9.6 volts, refer to
Starter Motorin Diagnosis and Testing. If starter
motor is OK, refer toEngine Diagnosisin 9,
Engine for further testing of engine. If starter
motor is not OK, replace faulty starter motor.
(b) If voltage reads above 9.6 volts and current
(amperage) draw reads below specifications, refer
toFeed Circuit Testin this section.
(c) If voltage reads 12.5 volts or greater and
starter motor does not turn, refer toControl Cir-
cuit Testingin this section.
(d) If voltage reads 12.5 volts or greater and
starter motor turns very slowly, refer toFeed Cir-
cuit Testin this section.
NOTE: A cold engine will increase starter current
(amperage) draw reading, and reduce battery volt-
age reading.
FEED CIRCUIT TEST
The starter feed circuit test (voltage drop method)
will determine if there is excessive resistance in
high-amperage feed circuit. For complete starter wir-
ing circuit diagrams, refer 8, Wiring Diagrams.
When performing these tests, it is important to
remember that voltage drop is giving an indication of
resistance between two points at which voltmeter
probes are attached.
Example:When testing resistance of positive bat-
tery cable, touch voltmeter leads to positive battery
cable clamp and cable connector at starter solenoid.
If you probe positive battery terminal post and cable
connector at starter solenoid, you are reading com-
bined voltage drop in positive battery cable clamp-to-
terminal post connection and positive battery cable.
The following operation will require a voltmeter
accurate to 1/10 (0.10) volt. Before performing tests,
be certain that following procedures are accom-
plished:
²Battery is fully-charged and load-tested. Refer to
Batteryin 8, Battery.
²Fully engage parking brake.
²If equipped with manual transmission, place
gearshift selector lever in Neutral position and block
clutch pedal in fully depressed position. If equipped
with automatic transmission, place gearshift selector
lever in Park position.
²Verify that all lamps and accessories are turned
off.
Fig. 1 VOLTS-AMPS TESTER CONNECTIONS -
TYPICAL
1 - POSITIVE CLAMP
2 - NEGATIVE CLAMP
3 - INDUCTION AMMETER CLAMP
DRSTARTING 8F - 29
STARTING (Continued)
²To prevent a gasoline engine from starting,
remove Automatic ShutDown (ASD) relay. To prevent
a diesel engine from starting, remove Fuel Pump
Relay. These relays are located in Power Distribution
Center (PDC). Refer to label on PDC cover for relay
location.
(1) Connect positive lead of voltmeter to negative
battery cable terminal post. Connect negative lead of
voltmeter to negative battery cable clamp (Fig. 2).
Rotate and hold ignition switch in Start position.
Observe voltmeter. If voltage is detected, correct poor
contact between cable clamp and terminal post.
Note: Certain diesel equipped models use dual
batteries. If equipped with dual battery system,
procedure must be performed twice, once for
each battery.
(2) Connect positive lead of voltmeter to positive
battery terminal post. Connect negative lead of volt-
meter to battery positive cable clamp (Fig. 3). Rotate
and hold ignition switch in Start position. Observe
voltmeter. If voltage is detected, correct poor contact
between cable clamp and terminal post.Note: Cer-
tain diesel equipped models use dual batteries.
If equipped with dual battery system, this pro-
cedure must be performed twice, once for each
battery.
(3) Connect voltmeter to measure between battery
positive terminal post and starter solenoid battery
terminal stud (Fig. 4). Rotate and hold ignition
switch in Start position. Observe voltmeter. If read-
ing is above 0.2 volt, clean and tighten battery cable
connection at solenoid. Repeat test. If reading is still
above 0.2 volt, replace faulty positive battery cable.
Note: Certain diesel equipped models use dual
batteries. If equipped with dual battery system,
this procedure must be performed on driver
side battery only.(4) Connect voltmeter to measure between nega-
tive battery terminal post and a good clean ground
on engine block (Fig. 5). Rotate and hold ignition
switch in Start position. Observe voltmeter. If read-
ing is above 0.2 volt, clean and tighten negative bat-
tery cable attachment on engine block. Repeat test. If
reading is still above 0.2 volt, replace faulty negative
battery cable.Note: Certain diesel equipped mod-
els use dual batteries. If equipped with dual
battery system, this procedure must be per-
formed twice, once for each battery.
Fig. 2 TEST BATTERY NEGATIVE CONNECTION
RESISTANCE - TYPICAL
1 - VOLTMETER
2 - BATTERY
Fig. 3 TEST BATTERY POSITIVE CONNECTION
RESISTANCE - TYPICAL
1 - VOLTMETER
2 - BATTERY
Fig. 4 TEST BATTERY POSITIVE CABLE
RESISTANCE - TYPICAL
1 - BATTERY
2 - VOLTMETER
3 - STARTER MOTOR
8F - 30 STARTINGDR
STARTING (Continued)
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION
Engine diagnosis is helpful in determining the
causes of malfunctions not detected and remedied by
routine maintenance.
These malfunctions may be classified as either per-
formance (e.g., engine idles rough and stalls) or
mechanical (e.g., a strange noise).
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING) - PERFORMANCE and (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)ÐMECHANICAL for
possible causes and corrections of malfunctions.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY -
DIAGNOSIS AND TESTING) and (Refer to 14 -
FUEL SYSTEM/FUEL INJECTION - DIAGNOSIS
AND TESTING) for the fuel system diagnosis.Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following diagnosis:
²Cylinder Compression Pressure Test (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
²Cylinder Combustion Pressure Leakage Test
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING).
²Engine Cylinder Head Gasket Failure Diagnosis
(Refer to 9 - ENGINE/CYLINDER HEAD - DIAGNO-
SIS AND TESTING).
²Intake Manifold Leakage Diagnosis (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
DIAGNOSIS AND TESTING).
DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - PERFORMANCE
CONDITION POSSIBLE CAUSE CORRECTION
ENGINE WILL NOT START 1. Weak battery 1. Charge or replace as necessary.
2. Corroded or loose battery
connections.2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to the terminals.
3. Faulty starter. 3. (Refer to 8 - ELECTRICAL/
STARTING - DIAGNOSIS AND
TESTING).
4. Faulty coil or control unit. 4. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION
COIL - REMOVAL).
5. Incorrect spark plug gap. 5. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG
- CLEANING).
6. Incorrect right bank cam timing. 6. Refer to engine timing in this
section.
7. Dirt or water in fuel system. 7. Clean system and replace fuel
filter.
8.Faulty fuel pump, relay or wiring. 8.Repair or replace as necessary.
9. Faulty cam or crank sensor 9. Refer to Ignition system.
ENGINE STALLS OR ROUGH IDLE 1. Vacuum leak. 1. Inspect intake manifold and
vacuum hoses, repair or replace as
necessary.
2. Faulty crank position sensor 2. Replace crank position sensor.
3. Faulty coil. 3. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION
COIL - REMOVAL).
9 - 4 ENGINE - 3.7LDR
ENGINE - 3.7L (Continued)
ENGINE - 4.7L
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - PERFORMANCE
CONDITION POSSIBLE CAUSE CORRECTION
ENGINE WILL NOT START 1. Weak battery 1. Charge or replace as necessary.
2. Corroded or loose battery
connections.2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to the terminals.
3. Faulty starter. 3. (Refer to 8 - ELECTRICAL/
STARTING - DIAGNOSIS AND
TESTING).
4. Faulty coil or control unit. 4. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION
COIL - REMOVAL).
5. Incorrect spark plug gap. 5. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG
- CLEANING).
6. Dirt or water in fuel system. 6. Clean system and replace fuel
filter.
7. Faulty fuel pump, relay or wiring. 7. Repair or replace as necessary.
ENGINE STALLS OR ROUGH IDLE 1. Idle speed set to low. 1. (Refer to 14 - FUEL SYSTEM/
FUEL INJECTION/IDLE AIR
CONTROL MOTOR - REMOVAL).
2. Idle mixture too lean or too rich. 2. Refer to Powertrain Diagnosis
Information.
3. Vacuum leak. 3. Inspect intake manifold and
vacuum hoses, repair or replace as
necessary.
4. Faulty coil. 4. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION
COIL - REMOVAL).
5. Incorrect engine timing. 5. (Refer to 9 - ENGINE/VALVE
TIMING - STANDARD
PROCEDURE).
9 - 90 ENGINE - 4.7LDR
(19) Disconnect throttle and speed control cables.
(20) Disconnect tube from both the left and right
side crankcase breathers (Fig. 2). Remove breathers
(21) Discharge A/C system (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/REFRIG-
ERANT - STANDARD PROCEDURE).
(22) Remove A/C compressor (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/A/C COM-
PRESSOR - REMOVAL).
(23) Remove shroud, fan assembly (Refer to 7 -
COOLING/ENGINE/FAN DRIVE VISCOUS
CLUTCH - REMOVAL) and accessory drive belt
(Refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE
BELTS - REMOVAL).
(24) Disconnect transmission oil cooler lines at the
radiator.
(25) Disconnect radiator upper and lower hoses.
(26) Remove radiator (Refer to 7 - COOLING/EN-
GINE/RADIATOR - REMOVAL), A/C condenser
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/A/C CONDENSER - REMOVAL) and
transmission oil cooler.
(27) Remove generator (Refer to 8 - ELECTRICAL/
CHARGING/GENERATOR - REMOVAL).
(28) Disconnect the two heater hoses from the tim-
ing chain cover and heater core.
(29) Unclip and remove heater hoses and tubes
from the intake manifold.
(30) Disconnect engine harness at the following
points :
²Intake air temperature (IAT) sensor (Fig. 3)
²Fuel Injectors
²Throttle Position (TPS) Switch
²Idle Air Control (IAC) Motor
²Engine Oil Pressure Switch
²Engine Coolant Temperature (ECT) Sensor
²Manifold absolute pressure (MAP) Sensor
²Camshaft Position (CMP) Sensor
²Coil Over Plugs(31) Disconnect the vacuum lines at the throttle
body and intake manifold.
(32) Release fuel rail pressure (Refer to 14 - FUEL
SYSTEM/FUEL DELIVERY - STANDARD PROCE-
DURE) then disconnect the fuel supply quick connect
fitting at the fuel rail (Refer to 14 - FUEL SYSTEM/
FUEL DELIVERY/QUICK CONNECT FITTING -
STANDARD PROCEDURE).
(33) Remove power steering pump and position out
of the way.
(34) Install Special Tools 8400 Lifting Studs, into
the cylinder heads.
(35) Install Engine Lifting Fixture Special Tool
8347 (Fig. 4) following these steps.
²Holding the lifting fixture at a slight angle, slide
the large bore in the front plate over the hex portion
of the lifting stud.
²Position the two remaining fixture arms onto
the two Special Tools 8400 Lifting Studs, in the cyl-
inder heads.
²Pull foward and upward on the lifting fixture so
that the lifting stud rest in the slotted area below the
large bore.
Fig. 2 Crankcase Breather Connection Points
1 - CRANKCASE BREATHERS
Fig. 3 Throttle Body Connection Points
1 - THROTTLE BODY
2 - TPS
3 - IAC MOTOR
4 - IAT SENSOR
5 - MOUNTING SCREWS
9 - 96 ENGINE - 4.7LDR
ENGINE - 4.7L (Continued)
INSTALLATION
(1) Position the oil pump onto the crankshaft and
install one oil pump retaining bolts.
(2) Position the primary timing chain tensioner
and install three retaining bolts.
(3) Tighten the oil pump and primary timing chain
tensioner retaining bolts to 28 N´m (250 in. lbs.) in
the sequence shown (Fig. 107).
(4) Install the secondary timing chain tensioners
and timing chains (Refer to 9 - ENGINE/VALVE
TIMING/TIMING BELT/CHAIN AND SPROCKETS -
INSTALLATION).
(5) Install the timing chain cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
(6) Install the pick-up tube and oil pan (Refer to 9
- ENGINE/LUBRICATION/OIL PAN - INSTALLA-
TION).
INTAKE MANIFOLD
DESCRIPTION
The intake manifold is made of a composite mate-
rial and features long runners which maximizes low
end torque. The intake manifold uses single plane
sealing which consist of eight individual press in
place port gaskets to prevent leaks. Eight studs and
two bolts are used to fasten the intake to the head.
DIAGNOSIS AND TESTINGÐINTAKE
MANIFOLD LEAKAGE
An intake manifold air leak is characterized by
lower than normal manifold vacuum. Also, one or
more cylinders may not be functioning.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
(1) Start the engine.
(2) Spray a small stream of water at the suspected
leak area.
(3) If a change in RPM is observed the area of the
suspected leak has been found.
(4) Repair as required.
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove resonator assembly and air inlet hose.
(3) Disconnect throttle and speed control cables.
(4) Disconnect electrical connectors for the follow-
ing components:
²Manifold Absolute Pressure (MAP) Sensor
²Intake Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Coolant Temperature (CTS) Sensor
²Idle Air Control (IAC) Motor
(5) Disconnect brake booster hose and positive
crankcase ventilation (PCV) hose.
(6) Disconnect generator electrical connections.
(7) Disconnect air conditioning compressor electri-
cal connections.
(8) Disconnect left and right radio suppressor
straps.
(9) Disconnect and remove ignition coil towers
(Refer to 8 - ELECTRICAL/IGNITION CONTROL/
IGNITION COIL - REMOVAL).
(10) Remove top oil dipstick tube retaining bolt
and ground strap.
(11) Bleed fuel system (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY - STANDARD PROCE-
DURE).
(12) Remove fuel rail (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL RAIL - REMOVAL).
(13) Remove throttle body assembly and mounting
bracket.
(14) Drain cooling system below coolant tempera-
ture level (Refer to 7 - COOLING - STANDARD
PROCEDURE).
(15) Remove the heater hoses from the engine
front cover and the heater core.
Fig. 107 Oil Pump And Primary Timing Chain
Tensioner Tightening Sequence
DRENGINE - 4.7L 9 - 159
OIL PUMP (Continued)