Emission DODGE RAM 2002 Service Manual PDF

²If the MIL is ON and any other emissions DTC
was set (not an OBD II monitor), a good trip occurs
when the Oxygen Sensor Monitor and Catalyst Mon-
itor have been completed, or two minutes of engine
run time if the Oxygen Sensor Monitor and Catalyst
Monitor have been stopped from running.
Fuel System Good Trip
To count a good trip (three required) and turn off
the MIL, the following conditions must occur:
²Engine in closed loop
²Operating in Similar Conditions Window
²Short Term multiplied by Long Term less than
threshold
²Less than threshold for a predetermined time
If all of the previous criteria are met, the PCM will
count a good trip (three required) and turn off the MIL.
Misfire Good Trip
If the following conditions are met the PCM will
count one good trip (three required) in order to turn
off the MIL:
²Operating in Similar Condition Window
²1000 engine revolutions with no misfire
Warm-Up Cycles
Once the MIL has been extinguished by the Good Trip
Counter, the PCM automatically switches to a Warm-Up
Cycle Counter that can be viewed on the DRB III.
Warm-Up Cycles are used to erase DTCs and Freeze
Frames. Forty Warm-Up cycles must occur in order for
the PCM to self-erase a DTC and Freeze Frame. A
Warm-Up Cycle is defined as follows:
²Engine coolant temperature must start below
and rise above 160É F
²Engine coolant temperature must rise by 40É F
²No further faults occur
Freeze Frame Data Storage
Once a failure occurs, the Task Manager records
several engine operating conditions and stores it in a
Freeze Frame. The Freeze Frame is considered one
frame of information taken by an on-board data
recorder. When a fault occurs, the PCM stores the
input data from various sensors so that technicians
can determine under what vehicle operating condi-
tions the failure occurred.
The data stored in Freeze Frame is usually
recorded when a system fails the first time for two
trip faults. Freeze Frame data will only be overwrit-
ten by a different fault with a higher priority.
CAUTION: Erasing DTCs, either with the DRB III or
by disconnecting the battery, also clears all Freeze
Frame data.
Similar Conditions Window
The Similar Conditions Window displays informa-
tion about engine operation during a monitor. Abso-lute MAP (engine load) and Engine RPM are stored
in this window when a failure occurs. There are two
different Similar conditions Windows: Fuel System
and Misfire.
FUEL SYSTEM
²Fuel System Similar Conditions WindowÐ
An indicator that 'Absolute MAP When Fuel Sys Fail'
and 'RPM When Fuel Sys Failed' are all in the same
range when the failure occurred. Indicated by switch-
ing from 'NO' to 'YES'.
²Absolute MAP When Fuel Sys FailÐ The
stored MAP reading at the time of failure. Informs
the user at what engine load the failure occurred.
²Absolute MAPÐ A live reading of engine load
to aid the user in accessing the Similar Conditions
Window.
²RPM When Fuel Sys FailÐ The stored RPM
reading at the time of failure. Informs the user at
what engine RPM the failure occurred.
²Engine RPMÐ A live reading of engine RPM
to aid the user in accessing the Similar Conditions
Window.
²Adaptive Memory FactorÐ The PCM utilizes
both Short Term Compensation and Long Term Adap-
tive to calculate the Adaptive Memory Factor for
total fuel correction.
²Upstream O2S VoltsÐ A live reading of the
Oxygen Sensor to indicate its performance. For
example, stuck lean, stuck rich, etc.
²SCW Time in Window (Similar Conditions
Window Time in Window)Ð A timer used by the
PCM that indicates that, after all Similar Conditions
have been met, if there has been enough good engine
running time in the SCW without failure detected.
This timer is used to increment a Good Trip.
²Fuel System Good Trip CounterÐATrip
Counter used to turn OFF the MIL for Fuel System
DTCs. To increment a Fuel System Good Trip, the
engine must be in the Similar Conditions Window,
Adaptive Memory Factor must be less than cali-
brated threshold and the Adaptive Memory Factor
must stay below that threshold for a calibrated
amount of time.
²Test Done This TripÐ Indicates that the
monitor has already been run and completed during
the current trip.
MISFIRE
²Same Misfire Warm-Up StateÐ Indicates if
the misfire occurred when the engine was warmed up
(above 160É F).
²In Similar Misfire WindowÐ An indicator
that 'Absolute MAP When Misfire Occurred' and
'RPM When Misfire Occurred' are all in the same
range when the failure occurred. Indicated by switch-
ing from 'NO' to 'YES'.
BR/BEEMISSIONS CONTROL 25 - 23
EMISSIONS CONTROL (Continued)

²Absolute MAP When Misfire OccurredÐ
The stored MAP reading at the time of failure.
Informs the user at what engine load the failure
occurred.
²Absolute MAPÐ A live reading of engine load
to aid the user in accessing the Similar Conditions
Window.
²RPM When Misfire OccurredÐ The stored
RPM reading at the time of failure. Informs the user
at what engine RPM the failure occurred.
²Engine RPMÐ A live reading of engine RPM
to aid the user in accessing the Similar Conditions
Window.
²Adaptive Memory FactorÐ The PCM utilizes
both Short Term Compensation and Long Term Adap-
tive to calculate the Adaptive Memory Factor for
total fuel correction.
²200 Rev CounterÐ Counts 0±100 720 degree
cycles.
²SCW Cat 200 Rev CounterÐ Counts when in
similar conditions.
²SCW FTP 1000 Rev CounterÐ Counts 0±4
when in similar conditions.
²Misfire Good Trip CounterÐ Counts up to
three to turn OFF the MIL.
²Misfire DataÐ Data collected during test.
²Test Done This TripÐ Indicates YES when the
test is done.
OPERATION - NON-MONITORED CIRCUITS -
GAS ENGINES
The PCM does not monitor the following circuits,
systems and conditions that could have malfunctions
causing driveability problems. The PCM might not
store diagnostic trouble codes for these conditions.
However, problems with these systems may cause the
PCM to store diagnostic trouble codes for other sys-
tems or components.EXAMPLE:a fuel pressure
problem will not register a fault directly, but could
cause a rich/lean condition or misfire. This could
cause the PCM to store an oxygen sensor or misfire
diagnostic trouble code
FUEL PRESSURE
The fuel pressure regulator controls fuel system
pressure. The PCM cannot detect a clogged fuel
pump inlet filter, clogged in-line fuel filter, or a
pinched fuel supply or return line. However, these
could result in a rich or lean condition causing the
PCM to store an oxygen sensor or fuel system diag-
nostic trouble code.
SECONDARY IGNITION CIRCUIT
The PCM cannot detect an inoperative ignition coil,
fouled or worn spark plugs, ignition cross firing, or
open spark plug cables.CYLINDER COMPRESSION
The PCM cannot detect uneven, low, or high engine
cylinder compression.
EXHAUST SYSTEM
The PCM cannot detect a plugged, restricted or
leaking exhaust system, although it may set a fuel
system fault.
FUEL INJECTOR MECHANICAL MALFUNCTIONS
The PCM cannot determine if a fuel injector is
clogged, the needle is sticking or if the wrong injector
is installed. However, these could result in a rich or
lean condition causing the PCM to store a diagnostic
trouble code for either misfire, an oxygen sensor, or
the fuel system.
EXCESSIVE OIL CONSUMPTION
Although the PCM monitors engine exhaust oxygen
content when the system is in closed loop, it cannot
determine excessive oil consumption.
THROTTLE BODY AIR FLOW
The PCM cannot detect a clogged or restricted air
cleaner inlet or filter element.
VACUUM ASSIST
The PCM cannot detect leaks or restrictions in the
vacuum circuits of vacuum assisted engine control
system devices. However, these could cause the PCM
to store a MAP sensor diagnostic trouble code and
cause a high idle condition.
PCM SYSTEM GROUND
The PCM cannot determine a poor system ground.
However, one or more diagnostic trouble codes may
be generated as a result of this condition. The mod-
ule should be mounted to the body at all times, also
during diagnostic.
PCM CONNECTOR ENGAGEMENT
The PCM may not be able to determine spread or
damaged connector pins. However, it might store
diagnostic trouble codes as a result of spread connec-
tor pins.
OPERATION - NON-MONITORED CIRCUITS -
DIESEL
The PCM and/or the ECM will not monitor certain
malfunctioning circuits or components that could
cause driveability problems. Also, a Diagnostic Trou-
ble Code (DTC) might not be stored for these mal-
functions. However, problems with these circuits or
components may cause the PCM/ECM to store DTC's
for other circuits or components.EXAMPLES:A cyl-
inder with low compression will not set a DTC
25 - 24 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)

directly, but may cause an engine misfire. This in
turn may cause the ECM to set a DTC for an engine
misfire. Or, a dirty or plugged air filter will not set a
DTC directly, but may cause lack of turbocharger
boost. This in turn may cause the ECM to set a DTC
for a boost pressure malfunction.
FUEL PRESSURE
Primary fuel pressure from the fuel tank to the
fuel injection pump is supplied by the low-pressure
fuel transfer pump. High-pressure to the fuel injec-
tors is supplied by the fuel injection pump. The ECM
cannot detect actual fuel pressure, a clogged fuel fil-
ter, clogged fuel screen, or a pinched fuel supply or
return line. However, a DTC may be set due to an
engine misfire.
CYLINDER COMPRESSION
The ECM cannot detect uneven, low, or high
engine cylinder compression. However, these could
result in a possible misfire which may set a DTC.
EXHAUST SYSTEM
The ECM cannot detect a plugged, restricted or
leaking exhaust system. However, DTC's may be set
for engine misfire, high intake manifold temperature,
high engine coolant temperature, turbocharger over-
boost or turbocharger underboost.
FUEL INJECTOR MECHANICAL MALFUNCTIONS
The ECM cannot determine if a fuel injector is
clogged, the needle is sticking or if the wrong injectoris installed. However, these could result in a possible
misfire which may set a DTC.
EXCESSIVE OIL CONSUMPTION
The ECM cannot determine excessive oil consump-
tion. However, if excess oil consumption is high
enough, it could result in a possible engine misfire
which may set a DTC.
AIR FLOW
The ECM cannot detect a clogged, restricted or
dirty air filter element, or a restriction in the air
inlet system. However, these could result in a possi-
ble misfire which may set a DTC.
AIR PRESSURE LEAKS
The ECM cannot detect leaks or restrictions in the
air intake system. However, these could cause the
ECM to store a Manifold Air Pressure (MAP) sensor
DTC (boost pressure problem detected).
PCM/ECM SYSTEM GROUNDS
The PCM/ECM cannot directly determine poor sys-
tem grounds. However, one or more DTC's may be
generated as a result of poor grounds.
PCM/ECM CONNECTOR ENGAGEMENT
The PCM/ECM may not be able to determine
spread, damaged or corroded connector pins. How-
ever, it might store DTC's as a result of spread con-
nector pins (circuits that are open).
BR/BEEMISSIONS CONTROL 25 - 25
EMISSIONS CONTROL (Continued)

OPERATION - AIR INJECTION SYSTEM
The air injection system adds a controlled amount
of air to the exhaust gases aiding oxidation of hydro-
carbons and carbon monoxide in the exhaust stream.
The system does not interfere with the ability of the
EGR system (if used) to control nitrous oxide (NOx)
emissions.
5.9L HDC ENGINE:Air is drawn into the pump
through a rubber tube that is connected to a fitting
on the air cleaner housing (Fig. 2).
8.0L V-10 ENGINE:Air is drawn into the pump
through a rubber tube that is connected to a fitting
on the air injection pump filter housing (Fig. 3). Air
is drawn into the filter housing from the front of the
vehicle with rubber tube. This tube is used as a
silencer to help prevent air intake noise at the open-
ing to the pump filter housing. An air filter is located
within the air pump filter housing (Fig. 3).
Air is then compressed by the air injector pump. It
is expelled from the pump and routed into a rubber
tube where it reaches the air pressure relief valve
(Fig. 1). Pressure relief holes in the relief valve willprevent excess downstream pressure. If excess down-
stream pressure occurs at the relief valve, it will be
vented into the atmosphere.
Air is then routed (Fig. 1) from the relief valve,
through a tube, down to a9Y9connector, through the
two one-way check valves and injected at both of the
catalytic convertors (referred to as downstream).
The two one-way check valves (Fig. 1) protect the
hoses, air pump and injection tubes from hot exhaust
gases backing up into the system. Air is allowed to
flow through these valves in one direction only
(towards the catalytic convertors).
Downstream air flow assists the oxidation process
in the catalyst, but does not interfere with EGR oper-
ation (if EGR system is used).
Fig. 2 Air Inlet for Air PumpÐ5.9L HDC Engine
1 - AIR FILTER HOUSING
2 - AIR INLET TUBE
3 - INLET AIR FITTING
4 - AIR INJECTION PUMP
5 - OUTLET AIR FITTING
Fig. 3 Air Inlet and Air Pump Air
1 - INJECTION PUMP AIR FILTER HOUSING
2 - R. F. INNER FENDER
3 - FILTER HOUSING MOUNTING NUT
4 - PRESSURE RELIEF VALVE
5 - HOSE CLAMPS
6 - AIR INJECTION PUMP
7 - AIR INLET REDUCER
8 - LID
25 - 28 AIR INJECTIONBR/BE
AIR INJECTION (Continued)

EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAP SYSTEM............32
SPECIFICATIONS
TORQUE - EVAP SYSTEM..............32
CCV HOSE
DESCRIPTION - 8.0L....................33
OPERATION - 8.0L......................33
EVAP/PURGE SOLENOID
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................34
FUEL FILLER CAP
DESCRIPTION.........................34
OPERATION...........................34
REMOVAL/INSTALLATION................34
LEAK DETECTION PUMP
DESCRIPTION.........................34OPERATION...........................34
REMOVAL.............................34
INSTALLATION.........................34
P C V VA LV E
DESCRIPTION - V-8 ENGINES.............35
OPERATION - V-8 ENGINES...............35
DIAGNOSIS AND TESTING - PCV VALVE -
5.9L................................36
VACUUM LINES
DESCRIPTION.........................37
VAPOR CANISTER
DESCRIPTION.........................37
OPERATION...........................37
REMOVAL.............................38
INSTALLATION.........................38
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAP SYSTEM
The evaporation control system prevents the emis-
sion of fuel tank vapors into the atmosphere. When
fuel evaporates in the fuel tank, the vapors pass
through vent hoses or tubes into the two charcoal
filled evaporative canisters. The canisters tempo-
rarily hold the vapors. The Powertrain Control Mod-
ule (PCM) allows intake manifold vacuum to draw
vapors into the combustion chambers during certain
operating conditions.
All 5.9L/8.0L gasoline powered engines use a duty
cycle purge system. The PCM controls vapor flow byoperating the duty cycle EVAP purge solenoid. Refer
to Duty Cycle EVAP Canister Purge Solenoid for
additional information.
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system. This pump is used as part of
OBD II requirements. Refer to Leak Detection Pump
in this group for additional information.
NOTE: The hoses used in this system are specially
manufactured. If replacement becomes necessary, it
is important to use only fuel resistant hose.
SPECIFICATIONS
TORQUE - EVAP SYSTEM
DESCRIPTION N´m Ft. Lbs. In. Lbs.
EVAP Canister Mounting Nuts 9 80
Leak Detection Pump Mounting Screws 1 11
Leak Detection Pump Filter Mounting Bolt 7 65
25 - 32 EVAPORATIVE EMISSIONSBR/BE

CCV HOSE
DESCRIPTION - 8.0L
The 8.0L V-10 engine is equipped with a Crankcase
Ventilation (CCV) system. The CCV system performs
the same function as a conventional PCV system, but
does not use a vacuum controlled valve (PCV valve).
A molded vacuum tube connects manifold vacuum
to the top of the right cylinder head (valve) cover.
The vacuum tube connects to a fixed orifice fitting
(Fig. 1) of a calibrated size 2.6 mm (0.10 inches).
OPERATION - 8.0L
A molded vacuum tube connects manifold vacuum to
the top of the right cylinder head (valve) cover. The vac-
uum tube connects to a fixed orifice fitting (Fig. 1) of a
calibrated size 2.6 mm (0.10 inches). The fitting meters
the amount of crankcase vapors drawn out of the
engine.The fixed orifice fitting is grey in color.A
similar fitting (but does not contain a fixed orifice) is
used on the left cylinder head (valve) cover. This fitting
is black in color. Do not interchange these two fittings.
When the engine is operating, fresh air enters the
engine and mixes with crankcase vapors. Manifold
vacuum draws the vapor/air mixture through the
fixed orifice and into the intake manifold. The vapors
are then consumed during engine combustion.
EVAP/PURGE SOLENOID
DESCRIPTION
All 5.9L/8.0L gasoline powered engines use a duty
cycle EVAP canister purge solenoid. The solenoid reg-ulates the rate of vapor flow from the EVAP canister
to the throttle body.
OPERATION
The Powertrain Control Module (PCM) operates
the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged. The
PCM de-energizes the solenoid during open loop oper-
ation.
The engine enters closed loop operation after it
reaches a specified temperature and the time delay
ends. During closed loop operation, the PCM ener-
gizes and de-energizes the solenoid 5 or 10 times per
second, depending upon operating conditions. The
PCM varies the vapor flow rate by changing solenoid
pulse width. Pulse width is the amount of time the
solenoid energizes. The PCM adjusts solenoid pulse
width based on engine operating condition.
REMOVAL
The duty cycle solenoid is attached to a bracket
mounted to the right inner fender (Fig. 2).
(1) Disconnect electrical wiring connector at sole-
noid (Fig. 2).
(2) Disconnect vacuum harness at solenoid.
(3) Remove solenoid from support bracket.
Fig. 1 Fixed Orifice FittingÐ8.0L V-10 EngineÐ
Typical
1 - VACUUM TUBE
2 - FIXED ORIFICE FITTING
3 - COIL PACKS
4 - ORIFICE FITTING HOSE CONNECTIONS
Fig. 2 Duty Cycle EVAP Canister Purge Solenoid
Location
1 - RIGHT-FRONT FENDER
2 - LDP FILTER
3 - DUTY CYCLE SOLENOID
4 - ELEC. CONNEC.
5 - LEAK DETECTION PUMP (LDP) (IF EQUIPPED)
6 - LDP ELEC. CONNEC.
BR/BEEVAPORATIVE EMISSIONS 25 - 33

INSTALLATION
(1) Install solenoid assembly to support bracket.
(2) Connect vacuum harness.
(3) Connect wiring connector.
FUEL FILLER CAP
DESCRIPTION
The plastic fuel tank filler tube cap is threaded
onto the end of the fuel fill tube. Certain models are
equipped with a 1/4 turn cap.
OPERATION
The loss of any fuel or vapor out of fuel filler tube
is prevented by the use of a pressure-vacuum fuel fill
cap. Relief valves inside the cap will release fuel tank
pressure at predetermined pressures. Fuel tank vac-
uum will also be released at predetermined values.
This cap must be replaced by a similar unit if
replacement is necessary. This is in order for the sys-
tem to remain effective.
CAUTION: Remove fill cap before servicing any fuel
system component to relieve tank pressure. If
equipped with a Leak Detection Pump (LDP), the
cap must be tightened securely. If cap is left loose,
a Diagnostic Trouble Code (DTC) may be set.
REMOVAL/INSTALLATION
If replacement of the 1/4 turn fuel tank filler tube
cap is necessary, it must be replaced with an identi-
cal cap to be sure of correct system operation.
CAUTION: Remove the fuel tank filler tube cap to
relieve fuel tank pressure. The cap must be
removed prior to disconnecting any fuel system
component or before draining the fuel tank.
LEAK DETECTION PUMP
DESCRIPTION
The Leak Detection Pump (LDP) is used only with
certain emission packages.
The LDP is a device used to detect a leak in the
evaporative system.
The pump contains a 3 port solenoid, a pump that
contains a switch, a spring loaded canister vent valve
seal, 2 check valves and a spring/diaphragm.
OPERATION
Immediately after a cold start, engine temperature
between 40ÉF and 86ÉF, the 3 port solenoid is briefly
energized. This initializes the pump by drawing airinto the pump cavity and also closes the vent seal.
During non-test test conditions, the vent seal is held
open by the pump diaphragm assembly which pushes
it open at the full travel position. The vent seal will
remain closed while the pump is cycling. This is due
to the operation of the 3 port solenoid which prevents
the diaphragm assembly from reaching full travel.
After the brief initialization period, the solenoid is
de-energized, allowing atmospheric pressure to enter
the pump cavity. This permits the spring to drive the
diaphragm which forces air out of the pump cavity
and into the vent system. When the solenoid is ener-
gized and de-energized, the cycle is repeated creating
flow in typical diaphragm pump fashion. The pump
is controlled in 2 modes:
PUMP MODE:The pump is cycled at a fixed rate
to achieve a rapid pressure build in order to shorten
the overall test time.
TEST MODE:The solenoid is energized with a
fixed duration pulse. Subsequent fixed pulses occur
when the diaphragm reaches the switch closure
point.
The spring in the pump is set so that the system
will achieve an equalized pressure of about 7.5 inches
of water.
When the pump starts, the cycle rate is quite high.
As the system becomes pressurized pump rate drops.
If there is no leak the pump will quit. If there is a
leak, the test is terminated at the end of the test
mode.
If there is no leak, the purge monitor is run. If the
cycle rate increases due to the flow through the
purge system, the test is passed and the diagnostic is
complete.
The canister vent valve will unseal the system
after completion of the test sequence as the pump
diaphragm assembly moves to the full travel position.
REMOVAL
The LDP and LDP filter are attached to a bracket
mounted to the right-inner fender (Fig. 2). The LDP
and LDP filter are replaced (serviced) as one unit.
(1) Carefully remove hose at LDP filter.
(2) Remove LDP filter mounting bolt and remove
from vehicle.
(3) Carefully remove vapor/vacuum lines at LDP.
(4) Disconnect electrical connector at LDP (Fig. 2).
(5) Remove LDP mounting screws and remove
LDP from vehicle.
INSTALLATION
The LDP and LDP filter are attached to a bracket
mounted to the right-inner fender (Fig. 2) . The LDP
and LDP filter are replaced (serviced) as one unit.
(1) Install LDP to mounting bracket. Tighten
screws to 1 N´m (11 in. lbs.) torque.
25 - 34 EVAPORATIVE EMISSIONSBR/BE
EVAP/PURGE SOLENOID (Continued)

(2) Install LDP filter to mounting bracket. Tighten
bolt to 7 N´m (65 in. lbs.) torque.
(3) Carefully install vapor/vacuum lines to LDP,
and install hose to LDP filter.The vapor/vacuum
lines and hoses must be firmly connected.
Check the vapor/vacuum lines at the LDP, LDP
filter and EVAP canister purge solenoid for
damage or leaks. If a leak is present, a Diagnos-
tic Trouble Code (DTC) may be set.
(4) Connect electrical connector to LDP.
PCV VALVE
DESCRIPTION - V-8 ENGINES
All 5.9L V-8 gas powered engines are equipped
with a closed crankcase ventilation system and a pos-
itive crankcase ventilation (PCV) valve. The 8.0L
V-10 engine is not equipped with a PCV valve. Refer
to Crankcase Ventilation SystemÐ8.0L V-10 Engine
for information.
This system consists of a PCV valve mounted on
the cylinder head (valve) cover with a hose extending
from the valve to the intake manifold (Fig. 3).
Another hose connects the opposite cylinder head
(valve) cover to the air cleaner housing to provide a
source of clean air for the system. A separate crank-
case breather/filter is not used.
OPERATION - V-8 ENGINES
The PCV system operates by engine intake mani-
fold vacuum (Fig. 4). Filtered air is routed into the
crankcase through the air cleaner hose. The metered
air, along with crankcase vapors, are drawn through
the PCV valve and into a passage in the intake man-
ifold. The PCV system manages crankcase pressure
and meters blow by gases to the intake system,
reducing engine sludge formation.
The PCV valve contains a spring loaded plunger.
This plunger meters the amount of crankcase vapors
routed into the combustion chamber based on intake
manifold vacuum.
When the engine is not operating or during an
engine pop-back, the spring forces the plunger back
against the seat (Fig. 5). This will prevent vapors
from flowing through the valve.
Fig. 3 Typical PCV Valve/Hose (Non±California
Shown)
1 - P C V VA LV E
2 - PCV VALVE HOSE CONNECTIONS
Fig. 4 Typical Closed Crankcase Ventilation System
1 - THROTTLE BODY
2 - AIR CLEANER
3 - AIR INTAKE
4 - P C V VA LV E
5 - COMBUSTION CHAMBER
6 - BLOW-BY GASES
7 - CRANKCASE BREATHER/FILTER
Fig. 5 Engine Off or Engine Pop-BackÐNo Vapor
Flow
BR/BEEVAPORATIVE EMISSIONS 25 - 35
LEAK DETECTION PUMP (Continued)

During periods of high manifold vacuum, such as
idle or cruising speeds, vacuum is sufficient to com-
pletely compress spring. It will then pull the plunger
to the top of the valve (Fig. 6). In this position there
is minimal vapor flow through the valve.
During periods of moderate manifold vacuum, the
plunger is only pulled part way back from inlet. This
results in maximum vapor flow through the valve
(Fig. 7).
DIAGNOSIS AND TESTING - PCV VALVE - 5.9L
(1) With engine idling, remove the PCV valve from
cylinder head (valve) cover. If the valve is not
plugged, a hissing noise will be heard as air passes
through the valve. Also, a strong vacuum should be
felt at the valve inlet (Fig. 8).
(2) Return the PCV valve into the valve cover.
Remove the fitting and air hose at the opposite valve
cover. Loosely hold a piece of stiff paper, such as a
parts tag, over the opening (rubber grommet) at the
valve cover (Fig. 9).
(3) The paper should be drawn against the opening
in the valve cover with noticeable force. This will be
after allowing approximately one minute for crank-
case pressure to reduce.
Fig. 6 High Intake Manifold VacuumÐMinimal Vapor
Flow
Fig. 7 Moderate Intake Manifold VacuumÐMaximum
Vapor Flow
Fig. 8 Vacuum Check at PCV
1 - PCV VALVE GROMMET
2 - PCV HOSE
3 - P C V VA LV E
4 - VACUUM MUST BE FELT AGAINST FINGER
5 - ENGINE VALVE COVER
Fig. 9 Vacuum Check at Valve Cover Opening
1 - STIFF PAPER PLACED OVER RUBBER GROMMET
2 - RUBBER GROMMET
3 - VALVE COVER
4 - FITTING REMOVED FROM VALVE COVER
5 - AIR TUBE
25 - 36 EVAPORATIVE EMISSIONSBR/BE
PCV VALVE (Continued)

(4) Turn engine off and remove PCV valve from
valve cover. The valve should rattle when shaken
(Fig. 10).
(5) Replace the PCV valve and retest the system if
it does not operate as described in the preceding
tests.Do not attempt to clean the old PCV valve.
(6) If the paper is not held against the opening in
valve cover after new valve is installed, the PCV
valve hose may be restricted and must be replaced.
The passage in the intake manifold must also be
checked and cleaned.
(7) To clean the intake manifold fitting, turn a 1/4
inch drill (by hand) through the fitting to dislodge
any solid particles. Blow out the fitting with shop air.
If necessary, use a smaller drill to avoid removing
any metal from the fitting.
VACUUM LINES
DESCRIPTION
A vacuum schematic for emission related items can
be found on the VECI label. Refer to Vehicle Emis-
sion Control Information (VECI) Label for label loca-
tion.
VAPOR CANISTER
DESCRIPTION
Two, maintenance free, EVAP canisters are used
with all 5.9L/8.0L gasoline powered engines. Both
canisters are mounted to a bracket located below
rear of vehicle cab on outside of right frame rail (Fig.
11).
OPERATION
Two, maintenance free, EVAP canisters are used
with all 5.9L/8.0L gasoline powered engines.The
EVAP canisters are filled with granules of an acti-
vated carbon mixture. Fuel vapors entering the
EVAP canisters are absorbed by the charcoal gran-
ules.
Fuel tank pressure vents into the EVAP canisters.
Fuel vapors are temporarily held in the canisters
until they can be drawn into the intake manifold.
The duty cycle EVAP canister purge solenoid allows
the EVAP canisters to be purged at predetermined
times and at certain engine operating conditions.
Fig. 10 Shake PCV
1 - PCV VALVE GROMMET
2 - P C V VA LV E
3 - PCV VALVE MUST RATTLE WHEN SHAKEN
Fig. 11 Location of EVAP Canisters
1 - MOUNTING NUTS
2 - FRAME RAIL (RIGHT)
3 - FRONT EVAP CANISTER
4 - REAR EVAP CANISTER
BR/BEEVAPORATIVE EMISSIONS 25 - 37
PCV VALVE (Continued)