1998 DODGE RAM 1500 temp send

resistance of the input from the on/off switch. The
ACM will also set and/or store a DTC for faults it
detects in the passenger airbag on/off switch circuits,
and will turn on the airbag indicator in the EMIC if
a fault has been detected.
The ACM receives battery current through two cir-
cuits; a fused ignition switch output (run) circuit
through a fuse in the Integrated Power Module
(IPM), and a fused ignition switch output (run-start)
circuit through a second fuse in the IPM. The ACM
receives ground through a ground circuit and take
out of the instrument panel wire harness. This take
out has a single eyelet terminal connector that is
secured by a ground screw to the instrument panel
support structure. These connections allow the ACM
to be operational whenever the ignition switch is in
the Start or On positions.
The ACM also contains an energy-storage capaci-
tor. When the ignition switch is in the Start or On
positions, this capacitor is continually being charged
with enough electrical energy to deploy the supple-
mental restraint components for up to one second fol-
lowing a battery disconnect or failure. The purpose of
the capacitor is to provide backup supplemental
restraint system protection in case there is a loss of
battery current supply to the ACM during an impact.
Two sensors are contained within the ACM, an
electronic impact sensor and a safing sensor. The
electronic impact sensors are accelerometers that
sense the rate of vehicle deceleration, which provide
verification of the direction and severity of an
impact. On models equipped with optional side cur-
tain airbags, the ACM also monitors inputs from two
remote side impact sensors located within both the
left and right B-pillars to control deployment of the
side curtain airbag units.
The safing sensor is an electronic accelerometer
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safing
sensor is used to verify the need for a supplemental
restraint deployment by detecting impact energy of a
lesser magnitude than that of the primary electronic
impact sensors, and must exceed a safing threshold
in order for the airbags to deploy. Vehicles equipped
with optional side curtain airbags feature a second
safing sensor within the ACM to provide confirma-
tion to the ACM microprocessor of side impact forces.
This second safing sensor is a bi-directional unit that
detects impact forces from either side of the vehicle.
Pre-programmed decision algorithms in the ACM
microprocessor determine when the deceleration rate
as signaled by the impact sensors and the safing sen-
sors indicate an impact that is severe enough to
require supplemental restraint system protection
and, based upon the severity of the monitored impact
and the status of the passenger airbag on/off switchinput, determines the level of front airbag deploy-
ment force required for each front seating position.
When the programmed conditions are met, the ACM
sends the proper electrical signals to deploy the dual
multistage front airbags at the programmed force
levels, the front seat belt tensioners and, if the vehi-
cle is so equipped, either side curtain airbag unit.
The hard wired inputs and outputs for the ACM
may be diagnosed and tested using conventional
diagnostic tools and procedures. However, conven-
tional diagnostic methods will not prove conclusive in
the diagnosis of the ACM, the PCI data bus network,
or the electronic message inputs to and outputs from
the ACM. The most reliable, efficient, and accurate
means to diagnose the ACM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, NEVER STRIKE OR DROP THE AIRBAG
CONTROL MODULE, AS IT CAN DAMAGE THE
IMPACT SENSOR OR AFFECT ITS CALIBRATION.
THE AIRBAG CONTROL MODULE CONTAINS THE
IMPACT SENSOR, WHICH ENABLES THE SYSTEM
TO DEPLOY THE SUPPLEMENTAL RESTRAINTS. IF
AN AIRBAG CONTROL MODULE IS ACCIDENTALLY
DROPPED DURING SERVICE, THE MODULE MUST
BE SCRAPPED AND REPLACED WITH A NEW UNIT.
FAILURE TO OBSERVE THIS WARNING COULD
RESULT IN ACCIDENTAL, INCOMPLETE, OR
IMPROPER SUPPLEMENTAL RESTRAINT DEPLOY-
MENT.
8O - 12 RESTRAINTSDR
AIRBAG CONTROL MODULE (Continued)

by the ACM to suit the monitored impact conditions
by providing one of three delay intervals between the
electrical signals provided to the two initiators. The
longer the delay between these signals, the less force-
fully the airbag will deploy.
When the ACM sends the proper electrical signals
to each initiator, the electrical energy generates
enough heat to initiate a small pyrotechnic charge
which, in turn ignites chemical pellets within the
inflator. Once ignited, these chemical pellets burn
rapidly and produce a large quantity of inert gas.
The inflator is sealed to the back of the airbag hous-
ing and a diffuser in the inflator directs all of the
inert gas into the airbag cushion, causing the cushion
to inflate. As the cushion inflates, the driver airbag
trim cover will split at predetermined breakout lines,
then fold back out of the way along with the horn
switch unit. Following an airbag deployment, the air-
bag cushion quickly deflates by venting the inert gas
towards the instrument panel through vent holes
within the fabric used to construct the back (steering
wheel side) panel of the airbag cushion.
Some of the chemicals used to create the inert gas
may be considered hazardous while in their solid
state before they are burned, but they are securely
sealed within the airbag inflator. Typically, both ini-
tiators are used and all potentially hazardous chem-
icals are burned during an airbag deployment event.
However, it is possible for only one initiator to be
used during a deployment due to an airbag system
fault; therefore, it is necessary to always confirm
that both initiators have been used in order to avoid
the improper disposal of potentially live pyrotechnic
or hazardous materials. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - SER-
VICE AFTER A SUPPLEMENTAL RESTRAINT
DEPLOYMENT).
The inert gas that is produced when the chemicals
are burned is harmless. However, a small amount of
residue from the burned chemicals may cause some
temporary discomfort if it contacts the skin, eyes, or
breathing passages. If skin or eye irritation is noted,
rinse the affected area with plenty of cool, clean
water. If breathing passages are irritated, move to
another area where there is plenty of clean, fresh air
to breath. If the irritation is not alleviated by these
actions, contact a physician.
REMOVAL
The following procedure is for replacement of a
faulty or damaged driver airbag. If the airbag is
faulty or damaged, but not deployed, review the rec-
ommended procedures for handling non-deployed
supplemental restraints. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - HAN-
DLING NON-DEPLOYED SUPPLEMENTALRESTRAINTS). If the driver airbag has been
deployed, review the recommended procedures for
service after a supplemental restraint deployment
before removing the airbag from the vehicle. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - SERVICE AFTER A SUPPLEMENTAL
RESTRAINT DEPLOYMENT).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, WHEN REMOVING A DEPLOYED AIRBAG,
RUBBER GLOVES, EYE PROTECTION, AND A
LONG-SLEEVED SHIRT SHOULD BE WORN. THERE
MAY BE DEPOSITS ON THE AIRBAG CUSHION AND
OTHER INTERIOR SURFACES. IN LARGE DOSES,
THESE DEPOSITS MAY CAUSE IRRITATION TO THE
SKIN AND EYES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) From the underside of the steering wheel,
remove the two screws that secure the driver airbag
to the steering wheel armature (Fig. 23).
(3) Pull the driver airbag away from the steering
wheel far enough to access the three electrical con-
nections on the back of the airbag housing (Fig. 24).
(4) Disconnect the steering wheel wire harness
connector for the horn switch from the horn switch
feed pigtail wire connector, which is located on the
back of the driver airbag housing.
CAUTION: Do not pull on the clockspring pigtail
wires or pry on the connector insulator to disen-
gage the connector from the driver airbag inflator
connector receptacle. Improper removal of these
pigtail wires and their connector insulators can
result in damage to the airbag circuits or connector
insulators.
8O - 24 RESTRAINTSDR
DRIVER AIRBAG (Continued)

OPERATION
The multistage passenger airbag is deployed by
electrical signals generated by the Airbag Control
Module (ACM) through the passenger airbag squib 1
and squib 2 circuits to the two initiators in the air-
bag inflator. By using two initiators, the airbag can
be deployed at multiple levels of force. The force level
is controlled by the ACM to suit the monitored
impact conditions by providing one of four delay
intervals between the electrical signals provided to
the two initiators. The longer the delay between
these signals, the less forcefully the airbag will
deploy.
When the ACM sends the proper electrical signals to
each initiator, the electrical energy generates enough
heat to initiate a small pyrotechnic charge which, in
turn ignites chemical pellets within the inflator. Once
ignited, these chemical pellets burn rapidly and pro-
duce a large quantity of inert gas. The inflator is
sealed to the airbag cushion and a diffuser in the infla-
tor directs all of the inert gas into the airbag cushion,
causing the cushion to inflate. As the cushion inflates,
the passenger airbag door will split at predetermined
tear seam lines concealed on the inside surface of the
door, then the door will pivot up over the top of the
instrument panel and out of the way. Following an air-
bag deployment, the airbag cushion quickly deflates by
venting the inert gas through vent holes within the
fabric used to construct the back (instrument panel
side) of the airbag cushion.
Typically, both initiators are used during an airbag
deployment event. However, it is possible for only one
initiator to be used during a deployment due to an
airbag system fault; therefore, it is necessary to
always confirm that both initiators have been used in
order to avoid the improper disposal of potentially
live pyrotechnic materials. (Refer to 8 - ELECTRI-
CAL/RESTRAINTS - STANDARD PROCEDURE -
SERVICE AFTER A SUPPLEMENTAL RESTRAINT
DEPLOYMENT).
REMOVAL
The following procedure is for replacement of a
faulty or damaged passenger airbag. If the airbag is
faulty or damaged, but not deployed, review the rec-
ommended procedures for handling non-deployed
supplemental restraints. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - HAN-
DLING NON-DEPLOYED SUPPLEMENTAL
RESTRAINTS). If the passenger airbag has been
deployed, review the recommended procedures for
service after a supplemental restraint deployment
before removing the airbag from the vehicle. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - SERVICE AFTER A SUPPLEMENTAL
RESTRAINT DEPLOYMENT).WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, WHEN REMOVING A DEPLOYED AIRBAG,
RUBBER GLOVES, EYE PROTECTION, AND A
LONG-SLEEVED SHIRT SHOULD BE WORN. THERE
MAY BE DEPOSITS ON THE AIRBAG UNIT AND
OTHER INTERIOR SURFACES. IN LARGE DOSES,
THESE DEPOSITS MAY CAUSE IRRITATION TO THE
SKIN AND EYES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Remove the lower surround from the instru-
ment panel. (Refer to 23 - BODY/INSTRUMENT
PANEL/LOWER SURROUND - REMOVAL).
(3) Remove the screw that secures the mounting
tab of the panel outlet housing to the upper glove box
opening reinforcement (Fig. 36).
(4) Remove the six screws that secure the inboard
and lower flanges of the passenger airbag door to the
instrument panel.
Fig. 36 Passenger Airbag Door Screws
1 - PASSENGER AIRBAG DOOR
2 - PANEL OUTLET SCREW (1)
3 - GLOVE BOX OPENING UPPER REINFORCEMENT
4 - DOOR SCREW (6)
8O - 40 RESTRAINTSDR
PASSENGER AIRBAG (Continued)

pressed inert gas. When the ACM sends the proper
electrical signal to the airbag inflator, the electrical
energy creates enough heat to ignite chemical pellets
within the inflator. Once ignited, these chemicals
burn rapidly and produce the pressure necessary to
rupture a containment disk in the inert gas canister.
The inflator and inert gas canister are sealed and
connected to a tubular manifold so that all of the
released gas is directed into the folded side curtain
airbag cushion, causing the cushion to inflate.
As the airbag cushion inflates it will drop down
from the roof rail between the edge of the headliner
and the side glass/body pillars to form a curtain-like
cushion to protect the vehicle occupants during a side
impact collision. The front tether keeps the front por-
tion of the side curtain bag taut, thus ensuring that
the bag will deploy in the proper position. Following
the airbag deployment, the airbag cushion quickly
deflates by venting the inert gas through the loose
weave of the cushion fabric, and the deflated cushion
hangs down loosely from the roof rail.
REMOVAL
The following procedure is for replacement of a
faulty or damaged side curtain airbag. If the airbag
is faulty or damaged, but not deployed, review the
recommended procedures for handling non-deployed
supplemental restraints. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - HAN-
DLING NON-DEPLOYED SUPPLEMENTAL
RESTRAINTS). If the side curtain airbag has been
deployed, review the recommended procedures for
service after a supplemental restraint deployment
before removing the airbag from the vehicle. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - SERVICE AFTER A SUPPLEMENTAL
RESTRAINT DEPLOYMENT).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.WARNING: TO AVOID PERSONAL INJURY OR
DEATH, WHEN REMOVING A DEPLOYED AIRBAG,
RUBBER GLOVES, EYE PROTECTION, AND A
LONG-SLEEVED SHIRT SHOULD BE WORN. THERE
MAY BE DEPOSITS ON THE AIRBAG UNIT AND
OTHER INTERIOR SURFACES. IN LARGE DOSES,
THESE DEPOSITS MAY CAUSE IRRITATION TO THE
SKIN AND EYES.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, USE EXTREME CARE TO PREVENT ANY
FOREIGN MATERIAL FROM ENTERING THE SIDE
CURTAIN AIRBAG, OR BECOMING ENTRAPPED
BETWEEN THE SIDE CURTAIN AIRBAG CUSHION
AND THE HEADLINER. FAILURE TO OBSERVE THIS
WARNING COULD RESULT IN OCCUPANT INJURIES
UPON AIRBAG DEPLOYMENT.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Remove the headliner from the vehicle. (Refer
to 23 - BODY/INTERIOR/HEADLINER -
REMOVAL).
(3) Remove the screw that secures the side curtain
airbag tether retainer to the base of the A-pillar near
the belt line (Fig. 53).
(4) Disengage the two side curtain airbag tether
plastic retainer clips from the A-pillar.
Fig. 53 Side Curtain Airbag Remove/Install - Typical
1 - ROOF SIDE RAIL
2 - SPRING NUT (4 - STD CAB/6 - QUAD CAB)
3 - SCREW (4 - STD CAB/6 - QUAD CAB)
4 - CLIP (2)
5 - RIVET NUT
6 - SCREW
7 - SIDE CURTAIN AIRBAG
8 - RETAINER (3 - STD CAB/5 - QUAD CAB)
9 - WIRE HARNESS CONNECTOR
DRRESTRAINTS 8O - 57
SIDE CURTAIN AIRBAG (Continued)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - CHECKING
ENGINE OIL PRESSURE
(1) Remove oil pressure sending unit (Fig. 93)and
install gauge assembly C-3292.
(2) Run engine until thermostat opens.
(3) Oil Pressure:
²Curb Idle - 25 kPa (4 psi) minimum
²3000 rpm - 170 - 758 kPa (25 - 110 psi)
(4) If oil pressure is 0 at idle, shut off engine.
Check for a clogged oil pick-up screen or a pressure
relief valve stuck open.
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
Begin with a thorough visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24 km (15 miles), and
repeat inspection.If the oil leak source is not posi-
tively identified at this time, proceed with the air
leak detection test method.
Air Leak Detection Test Method
(1) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(2) Remove the PCV valve from the cylinder head
cover. Cap or plug the PCV valve grommet.
(3) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kPa (3 PSI) of test pressure.
(4) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.
(5) If the leakage occurs at the rear oil seal area,
refer to the section, Inspection for Rear Seal Area
Leak.
(6) If no leaks are detected, turn off the air supply
and remove the air hose and all plugs and caps.
Install the PCV valve and breather cap hose.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak:
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, distributor seal,
Fig. 93 OIL PRESSURE SENDING UNIT -TYPICAL
1 - BELT
2 - OIL PRESSURE SENSOR
3 - OIL FILTER
4 - ELEC. CONNECTOR
9 - 152 ENGINE - 4.7LDR
LUBRICATION (Continued)

INSTALLATION
(1) Throughly clean all gasket resdue from the
engine block.
(2) Use extream care and clean all gasket resdue
from the retainer.
(3) Position the gasket onto the retainer.
(4) Position the retainer onto the engine block.
(5) Install the retainer mounting bolts. Tighten the
bolts to 15 N´m (132 in. lbs.) using a crisscross pat-
tern, starting with the bolt on the lower right.
(6) Install a new rear seal(Refer to 9 - ENGINE/
ENGINE BLOCK/CRANKSHAFT OIL SEAL - REAR
- INSTALLATION).
(7) Install the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - INSTALLATION).
(8) Install the drive plate / flywheel.
(9) Install the transmission.
(10) Check and verify engine oil level.
(11) Start engine and check for leaks.
FLEX PLATE
REMOVAL
(1) Remove the transmission.
(2) Remove the bolts and flexplate.
INSTALLATION
(1) Position the flexplate or flywheel onto the
crankshaft and install the bolts hand tight.
(2)For automatic transmissions:Tighten the
flexplate retaining bolts to 95 N´m (70 ft. lbs.).
(3)For manual transmissions:Tighten the fly-
wheel retaining bolts to 75 N´m (55 ft. lbs.).
(4) Install the transmission.
HYDRAULIC TAPPETS
DIAGNOSIS AND TESTING - HYDRAULIC
TAPPETS
Before disassembling any part of the engine to cor-
rect tappet noise, check the oil pressure. If vehicle
has no oil pressure gauge, install a reliable gauge at
the pressure sending-unit. The pressure should be
between 207-552 kPa (30-70 psi) at 3,000 RPM.
Check the oil level after the engine reaches normal
operating temperature. Allow 5 minutes to stabilize
oil level, check dipstick. The oil level in the pan
should never be above the FULL mark or below the
ADD OIL mark on dipstick. Either of these two con-
ditions could be responsible for noisy tappets.
OIL LEVEL
HIGH
If oil level is above the FULL mark, it is possible
for the connecting rods to dip into the oil. With the
engine running, this condition could create foam in
the oil pan. Foam in oil pan would be fed to the
hydraulic tappets by the oil pump causing them to
lose length and allow valves to seat noisily.
LOW
Low oil level may allow oil pump to take in air. When
air is fed to the tappets, they lose length, which allows
valves to seat noisily. Any leaks on intake side of oil
pump through which air can be drawn will create the
same tappet action. Check the lubrication system from
the intake strainer to the pump cover, including the
relief valve retainer cap. When tappet noise is due to
aeration, it may be intermittent or constant, and usu-
ally more than one tappet will be noisy. When oil level
and leaks have been corrected, operate the engine at
fast idle. Run engine for a sufficient time to allow all of
the air inside the tappets to be bled out.
TAPPET NOISE DIAGNOSIS
(1) To determine source of tappet noise, operate
engine at idle with cylinder head covers removed.
(2) Feel each valve spring or rocker arm to detect
noisy tappet. The noisy tappet will cause the affected
spring and/or rocker arm to vibrate or feel rough in
operation.
NOTE: Worn valve guides or cocked springs are
sometimes mistaken for noisy tappets. 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.
(3)
Valve tappet noise ranges from light noise to a
heavy click. A light noise is usually caused by excessive
leak-down around the unit plunger, or by the plunger
partially sticking in the tappet body cylinder. The tap-
pet should be replaced. A heavy click is caused by a tap-
pet check valve not seating, or by foreign particles
wedged between the plunger and the tappet body. This
will cause the plunger to stick in the down position.
This heavy click will be accompanied by excessive clear-
ance between the valve stem and rocker arm as valve
closes. In either case, tappet assembly should be
removed for inspection and cleaning.
(4) The valve train generates a noise very much
like a light tappet noise during normal operation.
Care must be taken to ensure that tappets are mak-
ing the noise. If more than one tappet seems to be
noisy, it's probably not the tappets.
9 - 210 ENGINE - 5.7LDR
CRANKSHAFT REAR OIL SEAL RETAINER (Continued)

(8) Torque the (3) bolts that attach the front axle
to the left engine bracket to 101 N´m (75 ft. lbs.).
(9) Install the engine oil filter, if removed.
(10) Install the front crossmember(Refer to 13 -
FRAME & BUMPERS/FRAME/FRONT CROSS-
MEMBER - INSTALLATION).
(11) Install the skid plate.
(12) Lower the vehicle.
(13) Reconnect the negative battery cable.
REAR MOUNT
REMOVAL
(1) Raise the vehicle on a hoist.
(2) Using a suitable jack, support transmission.
(3) Remove the nuts from the transmission mount
(Fig. 26).
(4) Remove the two bolts that attach the transmis-
sion mount to the engine bracket.
(5) Raise the transmission enough to remove the
mount from the crossmember.
(6) Remove the mount.
INSTALLATION
NOTE: Threadlocking compound must be applied to
the bolts before installation.(1) Install the two bolts that attach the transmis-
sion mount to the transmission bracket.
(2) Torque the bolts to 61N´m (45 ft.lbs.) torque.
(3) Lower the transmission so the transmission
mount rests on the crossmember, and the studs of
the transmission mount are aligned in the slots in
the crossmember.
(4) Install the nuts onto the transmission mount
studs through the crossmember access slot.
(5) Torque the nuts to 54N´m (40 ft. lbs.).
LUBRICATION
DESCRIPTION
The lubrication system (Fig. 27) is a full flow fil-
tration pressure feed type.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - CHECKING
ENGINE OIL PRESSURE
(1) Remove oil pressure sending unit and install
gauge assembly C-3292.
(2) Run engine until thermostat opens.
(3) Oil Pressure:
²Curb Idle±25 kPa (4 psi) minimum
²3000 rpm±170 - 758 kPa (25 - 110 psi)
(4) If oil pressure is 0 at idle, shut off engine.
Check for a clogged oil pick-up screen or a pressure
relief valve stuck open.
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
Begin with a thorough visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24 km (15 miles), and
repeat inspection.If the oil leak source is not pos-
itively identified at this time, proceed with the air
leak detection test method.
Fig. 26 TRANSMISSION MOUNT
1 - MOUNT
2 - CROSSMEMBER
3 - NUT
4 - BOLT
9 - 220 ENGINE - 5.7LDR
FRONT MOUNT (Continued)

FUEL LEVEL SENDING UNIT /
SENSOR
DESCRIPTION
The fuel gauge sending unit (fuel level sensor) is
attached to the side of the fuel tank module. The
sending unit consists of a float, an arm, and a vari-
able resistor track (card).
OPERATION
The fuel tank module on diesel powered models
has 2 different circuits (wires). Two of these circuits
are used at the fuel gauge sending unit for fuel
gauge operation. The diesel engine does not have a
fuel tank module mounted electric fuel pump. The
electric fuel pump (fuel transfer pump) is mounted to
the engine.
For Fuel Gauge Operation:A constant input
voltage source of about 12 volts (battery voltage) is
supplied to the resistor track on the fuel gauge send-
ing unit. This is fed directly from the Engine Control
Module (ECM).NOTE: For diagnostic purposes,
this 12V power source can only be verified with
the circuit opened (fuel tank module electrical
connector unplugged). With the connectors
plugged, output voltages will vary from about .6
volts at FULL, to about 7.0 volts at EMPTY.The
resistor track is used to vary the voltage (resistance)
depending on fuel tank float level. As fuel level
increases, the float and arm move up, which
decreases voltage. As fuel level decreases, the float
and arm move down, which increases voltage. The
varied voltage signal is returned back to the ECM
through the sensor return circuit.
Both of the electrical circuits between the fuel
gauge sending unit and the ECM are hard-wired (not
multi-plexed). After the voltage signal is sent from
the resistor track, and back to the ECM, the ECM
will interpret the resistance (voltage) data and send
a message across the multi-plex bus circuits to the
instrument panel cluster. Here it is translated into
the appropriate fuel gauge level reading. Refer to
Instrument Panel for additional information.
REMOVAL
REMOVAL/INSTALLATION
For diesel removal and installation procedures,
refer to the gas section of Fuel System/Fuel Delivery.
See Fuel Level Sending Unit/Sensor Removal/Instal-
lation.
FUEL LINES
DESCRIPTION
Low-Pressure Lines Are:
²the fuel supply line from fuel tank to fuel trans-
fer (lift) pump.
²the fuel return line back to fuel tank.
²the fuel drain (manifold) line at rear of cylinder
head.
²the fuel supply line from fuel filter to fuel injec-
tion pump.
²the fuel injection pump return line.
High-Pressure Lines Are:
²the fuel line from fuel injection pump to fuel
rail.
²the 6 fuel lines from fuel rail up to injector con-
nector tubes
WARNING: HIGH-PRESSURE FUEL LINES DELIVER
DIESEL FUEL UNDER EXTREME PRESSURE FROM
THE INJECTION PUMP TO THE FUEL INJECTORS.
THIS MAY BE AS HIGH AS 160,000 KPA (23,206
PSI). USE EXTREME CAUTION WHEN INSPECTING
FOR HIGH-PRESSURE FUEL LEAKS. INSPECT FOR
HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF
CARDBOARD. HIGH FUEL INJECTION PRESSURE
CAN CAUSE PERSONAL INJURY IF CONTACT IS
MADE WITH THE SKIN.
OPERATION
High-Pressure Lines
CAUTION: The high-pressure fuel lines must be
held securely in place in their holders. The lines
cannot contact each other or other components. Do
not attempt to weld high-pressure fuel lines or to
repair lines that are damaged. If lines are ever
kinked or bent, they must be replaced. Use only the
recommended lines when replacement of high-pres-
sure fuel line is necessary.
High-pressure fuel lines deliver fuel (under pres-
sure) of up to approximately 160,000 kPa (23,206
PSI) from the injection pump to the fuel injectors.
The lines expand and contract from the high-pres-
sure fuel pulses generated during the injection pro-
cess. All high-pressure fuel lines are of the same
length and inside diameter. Correct high-pressure
fuel line usage and installation is critical to smooth
engine operation.
DRFUEL DELIVERY - DIESEL 14 - 57