ECU CHRYSLER VOYAGER 2004 Service Manual

OPERATION
The Mechanical Instrument Cluster (MIC) per-
forms a four second bulb check via PCI communica-
tion with the Sentry Key Remote Entry Module
(SKREEM). After the bulb check, the lamp is con-
trolled according to SKREEM messages. Then, the
SKREEM sends messages to the BCM to operate the
light based upon the results of the Sentry Key
Remote Entry System (SKREES) self tests. The light
may be actuated in two possible ways, flashing or on
solid. If the light comes on and stays on solid after a
power-up test, this indicates that the SKREEM has
detected a system malfunction. If the SKREEM
detects an invalid key when the ignition switch is
moved to the ON position, it sends a message on thePCI bus to the MIC, to flash the light. The SKREEM
can also send a message to flash the light and gen-
erate a single audible chime at the same time. These
two events occurring simultaneously indicate that
the SKIS has been placed into the9Customer Learn9
mode (Refer to 8 - ELECTRICAL/VEHICLE THEFT
SECURITY/TRANSPONDER KEY - STANDARD
PROCEDURE). If the light comes on and stays on
after the power-up test, diagnosis of the SKREES
should be performed using a DRBIIItscan tool and
the appropriate Body Diagnostic Procedures informa-
tion. The light is a Light Emitting Diode (LED) and
is not a serviceable component.
8Q - 8 VEHICLE THEFT SECURITYRS
VTSS/SKIS INDICATOR LAMP (Continued)

WIPER MODULE
REMOVAL
(1) Release the hood latch and open hood.
(2) Disconnect and isolate the battery negative
cable.
(3) Remove the wiper arms.
(4) Remove the cowl cover (Refer to 23 - BODY/
EXTERIOR/COWL GRILLE - REMOVAL).
(5) Disconnect the positive lock on the wiper mod-
ule wire connector (Fig. 8).
(6) Disconnect the wiper module wire connector
from the engine compartment wire harness.
(7) Disconnect the windshield washer hose from
coupling outside the module.
(8) Disconnect the drain tubes from nipples on bot-
tom of the wiper module.
(9) Remove nuts holding wiper module to lower
windshield fence.
(10) Remove bolts holding the wiper module to the
dash panel (Fig. 9).
(11) Lift wiper module from weld-studs on lower
windshield fence.
CAUTION: Do not allow wiper module to rest on
brake master cylinder reservoir, damage to brake
system can result.(12) Remove wiper module.
INSTALLATION
(1) Position the wiper module into the cowl.
(2) Install the bolts that secure the wiper module
to the dash (Fig. 9).
(3) Install the nuts that retain the wiper module.
(4) Connect the drain tubes to the nipples on the
wiper module.
(5) Connect the windshield washer tube.
(6) Connect the wire harness connector to the
wiper module (Fig. 9).
(7) Connect the positive lock on the wiper module
wire connector (Fig. 8).
CAUTION: Do not allow wiper module to rest on
brake master cylinder reservoir, damage to brake
system can result.
(8) Install the cowl cover (Refer to 23 - BODY/EX-
TERIOR/COWL GRILLE - INSTALLATION).
(9) Install the wiper arms and blades.
(10) Connect the battery negative cable.
(11) Close the hood.
Fig. 8 WIPER MODULE WIRE CONNECTOR
1 - WIPER SYSTEM WIRE CONNECTOR
2 - LOCK TAB
3 - POSITIVE LOCK
4 - WIPER MODULE
Fig. 9 WIPER MODULE
1 - BOLT
2 - NUTS
3 - BOLT
4 - WIPER MODULE
5 - WINDSHIELD
RSWIPERS/WASHERS8R-15

WIRING
TABLE OF CONTENTS
page page
WIRING DIAGRAM INFORMATION....... 8W-01-1
COMPONENT INDEX.................. 8W-02-1
POWER DISTRIBUTION............... 8W-10-1
GROUND DISTRIBUTION.............. 8W-15-1
BUS COMMUNICATIONS.............. 8W-18-1
CHARGING SYSTEM.................. 8W-20-1
STARTING SYSTEM.................. 8W-21-1
FUEL/IGNITION SYSTEM.............. 8W-30-1
TRANSMISSION CONTROL SYSTEM..... 8W-31-1
VEHICLE SPEED CONTROL............ 8W-33-1
ANTILOCK BRAKES................... 8W-35-1
VEHICLE THEFT SECURITY SYSTEM..... 8W-39-1
INSTRUMENT CLUSTER............... 8W-40-1
HORN/CIGAR LIGHTER/POWER OUTLET . . 8W-41-1
AIR CONDITIONING-HEATER........... 8W-42-1
AIRBAG SYSTEM.................... 8W-43-1
INTERIOR LIGHTING.................. 8W-44-1
BODY CONTROL MODULE............. 8W-45-1
MESSAGE CENTER................... 8W-46-1AUDIO SYSTEM..................... 8W-47-1
REAR WINDOW DEFOGGER............ 8W-48-1
OVERHEAD CONSOLE................. 8W-49-1
FRONT LIGHTING.................... 8W-50-1
REAR LIGHTING..................... 8W-51-1
TURN SIGNALS...................... 8W-52-1
WIPERS............................ 8W-53-1
TRAILER TOW....................... 8W-54-1
POWER WINDOWS................... 8W-60-1
POWER DOOR LOCKS................ 8W-61-1
POWER MIRRORS................... 8W-62-1
POWER SEATS...................... 8W-63-1
POWER SUNROOF................... 8W-64-1
SPLICE INFORMATION................ 8W-70-1
CONNECTOR PIN-OUTS............... 8W-80-1
CONNECTOR/GROUND/SPLICE
LOCATION........................ 8W-91-1
POWER DISTRIBUTION SYSTEM........ 8W-97-1 RSWIRING
8W-1

8W-39 VEHICLE THEFT SECURITY SYSTEM
Component Page
Body Control Module........... 8W-39-2, 3, 6, 7,
8, 9, 10, 11, 12, 13
Clockspring........................ 8W-39-5
Driver Door Lock Switch........... 8W-39-11, 12
Front Control Module............... 8W-39-3, 5
Front Intrusion Sensor................ 8W-39-4
Fuse 8............................ 8W-39-5
Fuse 14............................ 8W-39-2
G102.............................. 8W-39-5
G200.......................... 8W-39-2, 3, 5
G300............ 8W-39-6, 7, 8, 9, 10, 11, 12, 13
G301............... 8W-39-6, 7, 8, 9, 10, 11, 12
G302............................. 8W-39-13
G303............................. 8W-39-13
High Note Horn..................... 8W-39-5
Hood Ajar Switch................... 8W-39-13
Horn Relay......................... 8W-39-5
Horn Switch........................ 8W-39-5
Ignition Switch.................... 8W-39-2, 3
Integrated Power Module.......... 8W-39-2, 3, 5
Left Cylinder Lock Switch......... 8W-39-11, 12
Left Front Door Ajar Switch............ 8W-39-6
Left Front Door Lock Motor/Ajar
Switch........................ 8W-39-6, 7
Left Sliding Door Control Module...... 8W-39-8, 9Component Page
Left Sliding Door Latch Sensing Switch . . . 8W-39-8
Left Sliding Door Lock Motor........... 8W-39-9
Left Sliding Door Lock Motor/Ajar
Switch......................... 8W-39-10
Liftgate Ajar Switch................. 8W-39-13
Liftgate Cinch/Release Motor.......... 8W-39-13
Low Note Horn...................... 8W-39-5
Passenger Door Lock Switch........ 8W-39-11, 12
Power Liftgate Module............... 8W-39-13
Rear Intrusion Sensor................ 8W-39-4
Remote Keyless Entry Antenna......... 8W-39-2
Right Cylinder Lock Switch........ 8W-39-11, 12
Right Front Door Ajar Switch........... 8W-39-6
Right Front Door Lock Motor/Ajar
Switch........................ 8W-39-6, 7
Right Sliding Door Control Module.... 8W-39-8, 9
Right Sliding Door Latch Sensing Switch . . 8W-39-8
Right Sliding Door Lock Motor.......... 8W-39-9
Right Sliding Door Lock Motor/Ajar
Switch......................... 8W-39-10
Sentry Key Remote Entry Module....... 8W-39-2
Siren............................. 8W-39-3
Thatcham Alarm Indicator............. 8W-39-4
Thatcham Alarm Module............ 8W-39-3, 4
RS8W-39 VEHICLE THEFT SECURITY SYSTEM8W-39-1

8W-97 POWER DISTRIBUTION SYSTEM
TABLE OF CONTENTS
page page
POWER DISTRIBUTION SYSTEM
DESCRIPTION..........................1
OPERATION............................1
SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS.........1
INTEGRATED POWER MODULE
DESCRIPTION..........................2
OPERATION............................2
REMOVAL.............................2
INSTALLATION..........................3IOD FUSE
DESCRIPTION..........................3
OPERATION............................3
POWER OUTLET
DESCRIPTION..........................4
OPERATION............................4
DIAGNOSIS AND TESTING
DIAGNOSIS & TESTING - POWER OUTLET . . 4
REMOVAL.............................5
INSTALLATION..........................5
POWER DISTRIBUTION
SYSTEM
DESCRIPTION
This group covers the various standard and
optional power distribution components used on this
model. The power distribution system for this vehicle
consists of the following components:
²Integrated Power Module (IPM)
²Front Control Module (FCM)
²Power Outlets
Refer to Wiring Diagrams for complete circuit sche-
matics.
The power distribution system also incorporates
various types of circuit control and protection fea-
tures, including:
²Automatic resetting circuit breakers
²Blade-type fuses
²Bus bars
²Cartridge fuses
²Circuit splice blocks
²Flashers
²Fusible links
²Relays
Following are general descriptions of the major
components in the power distribution system. See the
owner's manual in the vehicle glove box for more
information on the features and use of all of the
power distribution system components.
OPERATION
The power distribution system for this vehicle is
designed to provide safe, reliable, and centralized dis-
tribution points for the electrical current required to
operate all of the many standard and optional facto-
ry-installed electrical and electronic powertrain,
chassis, safety, security, comfort and convenience sys-
tems. At the same time, the power distribution sys-
tem was designed to provide ready access to these
electrical distribution points for the vehicle techni-
cian to use when conducting diagnosis and repair of
faulty circuits. The power distribution system can
also prove useful for the sourcing of additional elec-
trical circuits that may be required to provide the
electrical current needed to operate many accessories
that the vehicle owner may choose to have installed
in the aftermarket.
SPECIAL TOOLS
POWER DISTRIBUTION SYSTEMS
Terminal Pick Kit 6680
RS8W-97 POWER DISTRIBUTION SYSTEM8W-97-1

INTEGRATED POWER MODULE
DESCRIPTION
The Integrated Power Module (IPM) is a combina-
tion of the Power Distribution Center (PDC) and the
Front Control Module (FCM). The IPM is located in
the engine compartment, next to the battery on this
model (Fig. 1). The power distribution center mates
directly with the Front Control Module (FCM) to
form the IPM Fuse and Relay Center. The power dis-
tribution center (PDC) is a printed circuit board
based module that contains fuses and relays, while
the front control module contains the electronics con-
trolling the IPM and other functions. This IPM con-
nects directly to the battery positive via a four pin
connector. The ground connection is via two other
connectors. The IPM provides the primary means of
voltage distribution and protection for the entire
vehicle.
The molded plastic IPM housing includes a base
and cover. The IPM cover is easily opened or removed
for service access by squeezing the two marked cover
latches and has a fuse and relay layout map integral
to the inside surface of the cover. This IPM housing
base and cover are secured in place by an IPM
mounting bracket. This mounting bracket is designed
to allow the IPM to rotate counter-clockwise once the
locking tab is disengaged. The IPM mounting bracketis secured in place by bolts threaded into the left
front wheel house.
OPERATION
All of the current from the battery and the gener-
ator output enters the Integrated Power Module
(IPM) via a four- pin connector on the bottom of the
module. The IPM cover is unlatched and opened or
removed to access the fuses or relays. Internal con-
nections of all of the power distribution center cir-
cuits is accomplished by a combination of bus bars
and a printed circuit board. Refer to the Wiring sec-
tion of the service manual for complete IPM circuit
schematics.
REMOVAL
(1) Disconnect the negative and positive battery
cables.
(2) Remove the battery thermal guard from the
vehicle. Refer to the Battery section for the proce-
dure.
(3) Remove the battery from the vehicle. Refer to
the Battery section for the procedure.
(4) Using a flat-bladed screwdriver, twist the Inte-
grated Power Module (IPM) bracket retaining latch
outward to free the intelligent power module from its
mounting bracket (Fig. 2).
(5) Rotate the IPM counter-clockwise to access and
disconnect the various electrical connectors (Fig. 3).
(6) Free the IPM from its mounting bracket by
removing the IPM bracket clips from the hinge. A
screwdriver slipped up from under the hinge will free
the clips.
Fig. 1 BATTERY THERMAL GUARD
1 - BATTERY THERMAL GUARD
2 - INTEGRATED POWER MODULE
3 - FRONT CONTROL MODULE
Fig. 2 RELEASING INTEGRATED POWER MODULE
FROM ITS MOUNTING BRACKET
8W - 97 - 2 8W-97 POWER DISTRIBUTION SYSTEMRS

INSTALLATION
(1) Snap the left side of the Integrated Power Mod-
ule (IPM) housing in its mounting bracket and con-
nect the various electrical connectors. Care must be
taken that the Connector Positive Assurance (CPA)
on the five-pin B+ connector is positively engaged to
prevent generating a Diagnostic Trouble Code (DTC).
NOTE: IPM electrical connectors are color coded to
ease location reference.
(2) Being certain no wires are stressed or pinched,
rotate the IPM clock-wise until secured in mounting
bracket. An audible click may be heard.
(3) Install the battery in the vehicle. Refer to the
Battery section for the procedure.
(4) Install the battery thermal guard in the vehi-
cle. Refer to the Battery section for the procedure.
(5)
Connect the negative and positive battery cables.
(6) Using a diagnostic scan tool, check for any
stored diagnostic trouble codes and correct, check
that all vehicle options are operational before return-
ing the vehicle to service.
IOD FUSE
DESCRIPTION
All vehicles are equipped with an Ignition-Off
Draw (IOD) fuse that is removed from its normal
cavity in the Integrated Power Module (IPM) whenthe vehicle is shipped from the factory. Dealer per-
sonnel are to remove the IOD fuse from the storage
location and install it into the IPM fuse cavity
marked IOD as part of the preparation procedures
performed just prior to new vehicle delivery.
The IPM has a molded plastic cover that can be
removed to provide service access to all of the fuses
and relays in the IPM. An integral latch and hinges
are molded into the IPM cover for easy removal. A
fuse layout map is integral to the underside of the
IPM cover to ensure proper fuse and relay identifica-
tion. The IOD fuse is a 20 ampere blade-type mini
fuse and, when removed, it is stored in a fuse cavity
adjacent to the washer fuse within the IPM.
OPERATION
The term ignition-off draw identifies a normal condi-
tion where power is being drained from the battery with
the ignition switch in the Off position. The IOD fuse
feeds the memory and sleep mode functions for some of
the electronic modules in the vehicle as well as various
other accessories that require battery current when the
ignition switch is in the Off position, including the
clock. The only reason the IOD fuse is removed is to
reduce the normal IOD of the vehicle electrical system
during new vehicle transportation and pre-delivery stor-
age to reduce battery depletion, while still allowing
vehicle operation so that the vehicle can be loaded,
unloaded and moved as needed by both vehicle trans-
portation company and dealer personnel.
The IOD fuse is removed from the IPM fuse cavity
when the vehicle is shipped from the assembly plant.
Dealer personnel must install the IOD fuse when the
vehicle is being prepared for delivery in order to
restore full electrical system operation. Once the
vehicle is prepared for delivery, the IOD function of
this fuse becomes transparent and the fuse that has
been assigned the IOD designation becomes only
another Fused B(+) circuit fuse. The IOD fuse serves
no useful purpose to the dealer technician in the ser-
vice or diagnosis of any vehicle system or condition,
other than the same purpose as that of any other
standard circuit protection device.
The IOD fuse can be used by the vehicle owner as
a convenient means of reducing battery depletion
when a vehicle is to be stored for periods not to
exceed about thirty days. However, it must be
remembered that removing the IOD fuse will not
eliminate IOD, but only reduce this normal condition.
If a vehicle will be stored for more than about thirty
days, the battery negative cable should be discon-
nected to eliminate normal IOD; and, the battery
should be tested and recharged at regular intervals
during the vehicle storage period to prevent the bat-
tery from becoming discharged or damaged. Refer to
Battery Systemfor additional service information.
Fig. 3 DISCONNECTING IPM
1 - INTEGRATED POWER MODULE FUSE & RELAY CENTER
RS8W-97 POWER DISTRIBUTION SYSTEM8W-97-3
INTEGRATED POWER MODULE (Continued)

POWER OUTLET
DESCRIPTION
Accessory power outlets are standard equipment on
this model. Two power outlets are installed in the
instrument panel center lower bezel, which is located
near the bottom of the instrument panel center stack
area. Two additional power outlets are also incorpo-
rated into the vehicle, one on the left rear C-pillar
trim and the other in the center console, if equipped.
The power outlets bases are secured by a snap fit in
the appropriate bezels. A hinged plug flips closed to
conceal and protect the power outlet base when the
power outlet is not being used.
The power outlet receptacle unit and the power
outlet plugs are each available for service replace-
ment.
OPERATION
The power outlet base or receptacle shell is con-
nected to ground, and an insulated contact in the
bottom of the shell is connected to battery current.
The power outlet on the instrument panel marked
with a battery receives battery voltage from a fuse in
the Integrated Power Module (IPM) at all times. The
other power outlet on the instrument panel marked
with a key receives battery voltage only when the
key is in the on position.
The power outlet located in the center console
receives battery voltage all the time when positioned
between thefront seatsand key-on voltage when
positioned between therear seats. The power outlet
located on the C-pillar receives battery voltage only
when the key is in the on position.
DIAGNOSIS AND TESTING
DIAGNOSIS & TESTING - POWER OUTLET
For complete circuit diagrams, refer toCigar
Lighter/Power Outletin Wiring Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO RESTRAINTS BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN,
SEAT OR INSTRUMENT PANEL COMPONENT DIAG-
NOSIS OR SERVICE. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
(1) Check the fused B(+) fuse in the Integrated
Power Module (IPM). If OK, go to Step 2. If not OK,
repair the shorted circuit or component as required
and replace the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the IPM. If OK, go to Step 3. If not OK, repair the
open fused B(+) circuit to the IPM fuse as required.
(3) Open the power outlet door. Check for continu-
ity between the inside circumference of the power
outlet receptacle and a good ground. There should be
continuity. If OK, go to Step 4. If not OK, go to Step
5.
(4) Check for battery voltage at the insulated con-
tact located at the back of the power outlet recepta-
cle. If not OK, go to Step 5.
(5) Disconnect and isolate the battery negative
cable. Remove the appropriate bezel. Check for conti-
nuity between the ground circuit cavity of the power
outlet wire harness connector and a good ground.
There should be continuity. If OK, go to Step 6. If not
OK, repair the open ground circuit to ground as
required.
(6) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
power outlet wire harness connector. If OK, replace
the faulty power outlet receptacle. If not OK, repair
the open fused B(+) circuit to the IPM fuse as
required.
8W - 97 - 4 8W-97 POWER DISTRIBUTION SYSTEMRS

(41) Disconnect the knock sensor electrical connec-
tor (3.8L only).
(42) Disconnect the engine block heater electrical
connector (if equipped).
(43) Remove the accessory belt splash shield.
(44) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(45) Disconnect the radiator lower hose.
(46) Remove air conditioning compressor from
engine.
(47) Remove the generator (Refer to 8 - ELECTRI-
CAL/CHARGING/GENERATOR - REMOVAL).
(48)
Remove the water pump pulley attaching bolts
and position pulley between pump hub and housing.
(49) Disconnect the oil pressure switch electrical
connector.
(50) Disconnect wiring harness support clip from
engine oil dipstick tube.
(51) Install Special Tools 6912 and 8444 Adapters
on the right side (rear) of engine block (Fig. 9).
(52) Lower the vehicle.
(53) Remove the power steering pump and set
aside.
(54) Raise vehicle enough to allow engine dolly
Special Tool 6135 and cradle Special Tool 6710 withpost Special Tool 6848 and adaptor Special Tool 6909
to be installed under vehicle (Fig. 12).
(55) Loosen cradle/post mounts to allow movement
for positioning posts into locating holes on the engine
(Fig. 10) and (Fig. 11). Slowly lower vehicle and posi-
tion cradle/post mounts until the engine is resting on
posts. Tighten all cradle/post mounts to cradle frame.
This will keep mounts from moving when removing
or installing engine and transmission.
(56) Lower vehicle so the weight ofONLY THE
ENGINE AND TRANSMISSIONis on the cradle.
(57) Install and secure the safety straps to the cra-
dle fixture and around the engine (Fig. 12).
(58) Remove the engine right side mount to engine
attaching bolts (Fig. 13).
(59) Remove the left mount through bolt (Fig. 14).
(60) Raise vehicle slowly. It is necessary to move
the engine/transmission assembly with the dolly to
allow for removal around body flanges.
Fig. 8 POWERTRAIN SUPPORTS AND DUST COVER
1 - BRACKET - ENGINE REAR MOUNT
2 - BOLT - TRANSAXLE CASE COVER
3 - STRUT - TRANSAXLE TO ENGINE HORIZONTAL
4 - BOLT - HORIZONTAL STRUT
5 - BOLT - STRUT TO TRANSAXLE
6 - COVER - TRANSAXLE CASE LOWER
7 - STRUT - TRANSAXLE TO ENGINE
8 - BOLT - STRUT TO ENGINE
9 - BOLT - ENGINE REAR MOUNT BRACKET
Fig. 9 ADAPTER TOOLS MOUNTED ON BLOCK
1 - SPECIAL TOOL 6912
2 - SPECIAL TOOL 8444
Fig. 10 Positioning Special Tool 6848 for use with
Adapters 8444 & 6912
1 - SLOTS
2 - SPECIAL TOOLS 6848
9 - 88 ENGINE 3.3/3.8LRS
ENGINE 3.3/3.8L (Continued)

CYLINDER BORE
NOTE: The cylinder bores should be measured at
normal room temperature, 21ÉC (70ÉF).
The cylinder walls should be checked for out-of-
round and taper with Tool C119 or equivalent (Fig.
45) (Refer to 9 - ENGINE - SPECIFICATIONS). If
the cylinder walls are badly scuffed or scored, the
cylinder block should be replaced, and new pistons
and rings fitted.
Measure the cylinder bore at three levels in direc-
tions A and B (Fig. 45). Top measurement should be
10 mm (3/8 in.) down and bottom measurement
should be 10 mm (3/8 in.) up from bottom of bore.
(Refer to 9 - ENGINE - SPECIFICATIONS).
HYDRAULIC LIFTERS (CAM IN
BLOCK)
DESCRIPTION
The hydraulic lifters are a roller type design and
are positioned in the cylinder block. The lifters are
aligned and retained by a yoke and a retainer (Fig.
47).Lifter alignment is maintained by machined flats
on lifter body. Lifters are fitted in pairs into six
aligning yokes. The aligning yokes are secured by a
yoke retainer (Fig. 47).
DIAGNOSIS AND TESTING - HYDRAULIC
LIFTERS
HYDRAULIC LIFTERS DIAGNOSIS - PRELIMINARY
STEP
Before disassembling any part of the engine to cor-
rect lifter noise, check the engine oil pressure. (Refer
to 9 - ENGINE/LUBRICATION - DIAGNOSIS AND
TESTING)
Check engine oil level. The oil level in the pan
should never be above the MAX mark on dipstick, or
below the MIN mark. Either of these two conditions
could cause noisy lifters.
OIL LEVEL TOO HIGH
If oil level is above the MAX mark on dipstick, it is
possible for the connecting rods to dip into the oil
while engine is running and create foaming. Foam in
oil pan would be fed to the hydraulic lifters by the oil
pump causing them to become soft and allow valves
to seat noisily.
OIL LEVEL TOO LOW
Low oil level may allow pump to take in air which
when fed to the lifters it causes them to become soft
and allows valves to seat noisily. Any leaks on intake
side of pump, through which air can be drawn, will
create the same lifter noise. Check the lubrication
system from the intake strainer to the oil pump
cover, including the relief valve retainer cap. When
lifter noise is due to aeration, it may be intermittent
or constant, and usually more than one lifter will be
noisy. When oil level and leaks have been corrected,
the engine should be operated at fast idle to allow all
of the air inside of the lifters to be bled out.
VALVE TRAIN NOISE
To determine source of valve train noise, operate
engine at idle with cylinder head covers removed and
listen for source of the noise.
NOTE: Worn valve guides or cocked springs are
sometimes mistaken for noisy lifters. If such is the
case, noise may be dampened by applying side
thrust on the valve spring. If noise is not apprecia-
bly reduced, it can be assumed the noise is in the
tappet. Inspect the rocker arm push rod sockets
and push rod ends for wear.
Fig. 45 Checking Cylinder Bore Size
RSENGINE 3.3/3.8L9 - 113
ENGINE BLOCK (Continued)