check engine DODGE RAM 2002 Service Repair Manual

DESCRIPTION - TASK MANAGER
The PCM is responsible for efficiently coordinating
the operation of all the emissions-related compo-
nents. The PCM is also responsible for determining if
the diagnostic systems are operating properly. The
software designed to carry out these responsibilities
is call the 'Task Manager'.
DESCRIPTION - MONITORED SYSTEMS
There are new electronic circuit monitors that
check fuel, emission, engine and ignition perfor-
mance. These monitors use information from various
sensor circuits to indicate the overall operation of the
fuel, engine, ignition and emission systems and thus
the emissions performance of the vehicle.
The fuel, engine, ignition and emission systems
monitors do not indicate a specific component prob-
lem. They do indicate that there is an implied prob-
lem within one of the systems and that a specific
problem must be diagnosed.
If any of these monitors detect a problem affecting
vehicle emissions, the Malfunction Indicator Lamp
(MIL) will be illuminated. These monitors generate
Diagnostic Trouble Codes that can be displayed with
the MIL or a scan tool.
The following is a list of the system monitors:
²Misfire Monitor
²Fuel System Monitor
²Oxygen Sensor Monitor
²Oxygen Sensor Heater Monitor
²Catalyst Monitor
²Leak Detection Pump Monitor (if equipped)
All these system monitors require two consecutive
trips with the malfunction present to set a fault.
Refer to the appropriate Powertrain Diagnos-
tics Procedures manual for diagnostic proce-
dures.
The following is an operation and description of
each system monitor :
OXYGEN SENSOR (O2S) MONITOR
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The O2S is also the main sensing element for the
Catalyst and Fuel Monitors.The O2S can fail in any or all of the following
manners:
²slow response rate
²reduced output voltage
²dynamic shift
²shorted or open circuits
Response rate is the time required for the sensor to
switch from lean to rich once it is exposed to a richer
than optimum A/F mixture or vice versa. As the sen-
sor starts malfunctioning, it could take longer to
detect the changes in the oxygen content of the
exhaust gas.
The output voltage of the O2S ranges from 0 to 1
volt. A good sensor can easily generate any output
voltage in this range as it is exposed to different con-
centrations of oxygen. To detect a shift in the A/F
mixture (lean or rich), the output voltage has to
change beyond a threshold value. A malfunctioning
sensor could have difficulty changing beyond the
threshold value.
OXYGEN SENSOR HEATER MONITOR
If there is an oxygen sensor (O2S) shorted to voltage
DTC, as well as a O2S heater DTC, the O2S fault
MUST be repaired first. Before checking the O2S fault,
verify that the heater circuit is operating correctly.
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572 É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The voltage readings taken from the O2S sensor
are very temperature sensitive. The readings are not
accurate below 300ÉC. Heating of the O2S sensor is
done to allow the engine controller to shift to closed
loop control as soon as possible. The heating element
used to heat the O2S sensor must be tested to ensure
that it is heating the sensor properly.
The O2S sensor circuit is monitored for a drop in
voltage. The sensor output is used to test the heater
by isolating the effect of the heater element on the
O2S sensor output voltage from the other effects.
LEAK DETECTION PUMP MONITOR (IF EQUIPPED)
The leak detection assembly incorporates two pri-
mary functions: it must detect a leak in the evapora-
tive system and seal the evaporative system so the
leak detection test can be run.
BR/BEEMISSIONS CONTROL 25 - 17
EMISSIONS CONTROL (Continued)

The primary components within the assembly are:
A three port solenoid that activates both of the func-
tions listed above; a pump which contains a switch,
two check valves and a spring/diaphragm, a canister
vent valve (CVV) seal which contains a spring loaded
vent seal valve.
Immediately after a cold start, between predeter-
mined temperature thresholds limits, the three port
solenoid is briefly energized. This initializes the
pump by drawing air into the pump cavity and also
closes the vent seal. During non test conditions the
vent seal is held open by the pump diaphragm
assembly which pushes it open at the full travel posi-
tion. The vent seal will remain closed while the
pump is cycling due to the reed switch triggering of
the three port solenoid that 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, thus permitting the spring to drive the dia-
phragm which forces air out of the pump cavity and
into the vent system. When the solenoid is energized
and de energized, the cycle is repeated creating flow
in typical diaphragm pump fashion. The pump is con-
trolled 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 length.
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 7.5º H20.
The cycle rate of pump strokes is quite rapid as the
system begins to pump up to this pressure. As the
pressure increases, the cycle rate starts to drop off. If
there is no leak in the system, the pump would even-
tually stop pumping at the equalized pressure. If
there is a leak, it will continue to pump at a rate rep-
resentative of the flow characteristic of the size of the
leak. From this information we can determine if the
leak is larger than the required detection limit (cur-
rently set at .040º orifice by CARB). If a leak is
revealed during the leak test portion of the test, the
test is terminated at the end of the test mode and no
further system checks will be performed.
After passing the leak detection phase of the test,
system pressure is maintained by turning on the
LDP's solenoid until the purge system is activated.
Purge activation in effect creates a leak. The cycle
rate is again interrogated and when it increases due
to the flow through the purge system, the leak check
portion of 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.Evaporative system functionality will be verified by
using the stricter evap purge flow monitor. At an
appropriate warm idle the LDP will be energized to
seal the canister vent. The purge flow will be clocked
up from some small value in an attempt to see a
shift in the 02 control system. If fuel vapor, indicated
by a shift in the 02 control, is present the test is
passed. If not, it is assumed that the purge system is
not functioning in some respect. The LDP is again
turned off and the test is ended.
MISFIRE MONITOR
Excessive engine misfire results in increased cata-
lyst temperature and causes an increase in HC emis-
sions. Severe misfires could cause catalyst damage.
To prevent catalytic convertor damage, the PCM
monitors engine misfire.
The Powertrain Control Module (PCM) monitors
for misfire during most engine operating conditions
(positive torque) by looking at changes in the crank-
shaft speed. If a misfire occurs the speed of the
crankshaft will vary more than normal.
FUEL SYSTEM MONITOR
To comply with clean air regulations, vehicles are
equipped with catalytic converters. These converters
reduce the emission of hydrocarbons, oxides of nitro-
gen and carbon monoxide. The catalyst works best
when the Air Fuel (A/F) ratio is at or near the opti-
mum of 14.7 to 1.
The PCM is programmed to maintain the optimum
air/fuel ratio of 14.7 to 1. This is done by making
short term corrections in the fuel injector pulse width
based on the O2S sensor output. The programmed
memory acts as a self calibration tool that the engine
controller uses to compensate for variations in engine
specifications, sensor tolerances and engine fatigue
over the life span of the engine. By monitoring the
actual fuel-air ratio with the O2S sensor (short term)
and multiplying that with the program long-term
(adaptive) memory and comparing that to the limit,
it can be determined whether it will pass an emis-
sions test. If a malfunction occurs such that the PCM
cannot maintain the optimum A/F ratio, then the
MIL will be illuminated.
CATALYST MONITOR
To comply with clean air regulations, vehicles are
equipped with catalytic converters. These converters
reduce the emission of hydrocarbons, oxides of nitro-
gen and carbon monoxide.
Normal vehicle miles or engine misfire can cause a
catalyst to decay. This can increase vehicle emissions
and deteriorate engine performance, driveability and
fuel economy.
25 - 18 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)

The catalyst monitor uses dual oxygen sensors
(O2S's) to monitor the efficiency of the converter. The
dual O2S's sensor strategy is based on the fact that
as a catalyst deteriorates, its oxygen storage capacity
and its efficiency are both reduced. By monitoring
the oxygen storage capacity of a catalyst, its effi-
ciency can be indirectly calculated. The upstream
O2S is used to detect the amount of oxygen in the
exhaust gas before the gas enters the catalytic con-
verter. The PCM calculates the A/F mixture from the
output of the O2S. A low voltage indicates high oxy-
gen content (lean mixture). A high voltage indicates a
low content of oxygen (rich mixture).
When the upstream O2S detects a lean condition,
there is an abundance of oxygen in the exhaust gas.
A functioning converter would store this oxygen so it
can use it for the oxidation of HC and CO. As the
converter absorbs the oxygen, there will be a lack of
oxygen downstream of the converter. The output of
the downstream O2S will indicate limited activity in
this condition.
As the converter loses the ability to store oxygen,
the condition can be detected from the behavior of
the downstream O2S. When the efficiency drops, no
chemical reaction takes place. This means the con-
centration of oxygen will be the same downstream as
upstream. The output voltage of the downstream
O2S copies the voltage of the upstream sensor. The
only difference is a time lag (seen by the PCM)
between the switching of the O2S's.
To monitor the system, the number of lean-to-rich
switches of upstream and downstream O2S's is
counted. The ratio of downstream switches to
upstream switches is used to determine whether the
catalyst is operating properly. An effective catalyst
will have fewer downstream switches than it has
upstream switches i.e., a ratio closer to zero. For a
totally ineffective catalyst, this ratio will be one-to-
one, indicating that no oxidation occurs in the device.
The system must be monitored so that when cata-
lyst efficiency deteriorates and exhaust emissions
increase to over the legal limit, the MIL will be illu-
minated.
DESCRIPTION - TRIP DEFINITION
The term ªTripº has different meanings depending
on what the circumstances are. If the MIL (Malfunc-
tion Indicator Lamp) is OFF, a Trip is defined as
when the Oxygen Sensor Monitor and the Catalyst
Monitor have been completed in the same drive cycle.
When any Emission DTC is set, the MIL on the
dash is turned ON. When the MIL is ON, it takes 3
good trips to turn the MIL OFF. In this case, it
depends on what type of DTC is set to know what a
ªTripº is.For the Fuel Monitor or Mis-Fire Monitor (contin-
uous monitor), the vehicle must be operated in the
ªSimilar Condition Windowº for a specified amount of
time to be considered a Good Trip.
If a Non-Contiuous OBDII Monitor fails twice in a
row and turns ON the MIL, re-running that monitor
which previously failed, on the next start-up and
passing the monitor, is considered to be a Good Trip.
These will include the following:
²Oxygen Sensor
²Catalyst Monitor
²Purge Flow Monitor
²Leak Detection Pump Monitor (if equipped)
²EGR Monitor (if equipped)
²Oxygen Sensor Heater Monitor
If any other Emission DTC is set (not an OBDII
Monitor), a Good Trip is considered to be when the
Oxygen Sensor Monitor and Catalyst Monitor have
been completed; or 2 Minutes of engine run time if
the Oxygen Sensor Monitor or Catalyst Monitor have
been stopped from running.
It can take up to 2 Failures in a row to turn on the
MIL. After the MIL is ON, it takes 3 Good Trips to
turn the MIL OFF. After the MIL is OFF, the PCM
will self-erase the DTC after 40 Warm-up cycles. A
Warm-up cycle is counted when the ECT (Engine
Coolant Temperature Sensor) has crossed 160ÉF and
has risen by at least 40ÉF since the engine has been
started.
DESCRIPTION - COMPONENT MONITORS -
GAS ENGINES
There are several components that will affect vehi-
cle emissions if they malfunction. If one of these com-
ponents malfunctions the Malfunction Indicator
Lamp (MIL) will illuminate.
Some of the component monitors are checking for
proper operation of the part. Electrically operated
components now have input (rationality) and output
(functionality) checks. Previously, a component like
the Throttle Position sensor (TPS) was checked by
the PCM for an open or shorted circuit. If one of
these conditions occurred, a DTC was set. Now there
is a check to ensure that the component is working.
This is done by watching for a TPS indication of a
greater or lesser throttle opening than MAP and
engine rpm indicate. In the case of the TPS, if engine
vacuum is high and engine rpm is 1600 or greater,
and the TPS indicates a large throttle opening, a
DTC will be set. The same applies to low vacuum if
the TPS indicates a small throttle opening.
All open/short circuit checks, or any component
that has an associated limp-in, will set a fault after 1
trip with the malfunction present. Components with-
out an associated limp-in will take two trips to illu-
minate the MIL.
BR/BEEMISSIONS CONTROL 25 - 19
EMISSIONS CONTROL (Continued)

DESCRIPTION - COMPONENT MONITORS -
DIESEL ENGINES
There are several electrical components that will
affect vehicle emissions if they malfunction. If one of
these components is malfunctioning, a Diagnostic
Trouble Code (DTC) will be set by either the Power-
train Control Module (PCM) or the Engine Control
Module (ECM). The Malfunction Indicator Lamp
(MIL) will then be illuminated when the engine is
running.
These electrically operated components have input
(rationality) and output (functionality) checks. A
check is done by one or more components to check
the operation of another component.
Example:The Intake Manifold Air Temperature
(IAT) sensor is used to monitor intake manifold air
temperature over a period of time after a cold start.
If the temperature has not risen to a certain specifi-
cation during a specified time, a Diagnostic Trouble
Code (DTC) will be set for a problem in the manifold
air heater system.
All open/short circuit checks, or any component
that has an associated limp-in will set a DTC and
trigger the MIL after 1 trip with the malfunction
present. Components without an associated limp-in
will take two trips to illuminate the MIL.
OPERATION
OPERATION - GAS ENGINES
The Powertrain Control Module (PCM) monitors
many different circuits in the fuel injection, ignition,
emission and engine systems. If the PCM senses a
problem with a monitored circuit often enough to
indicate an actual problem, it stores a Diagnostic
Trouble Code (DTC) in the PCM's memory. If the
problem is repaired or ceases to exist, the PCM can-
cels the code after 40 warm-up cycles. Diagnostic
trouble codes that affect vehicle emissions illuminate
the Malfunction Indicator Lamp (MIL). The MIL is
displayed as an engine icon (graphic) on the instru-
ment panel. Refer to Malfunction Indicator Lamp in
this section.
Certain criteria must be met before the PCM
stores a DTC in memory. The criteria may be a spe-
cific range of engine RPM, engine temperature,
and/or input voltage to the PCM.
The PCM might not store a DTC for a monitored
circuit even though a malfunction has occurred. This
may happen because one of the DTC criteria for the
circuit has not been met.For example, assume the
diagnostic trouble code criteria requires the PCM to
monitor the circuit only when the engine operates
between 750 and 2000 RPM. Suppose the sensor's
output circuit shorts to ground when engine operatesabove 2400 RPM (resulting in 0 volt input to the
PCM). Because the condition happens at an engine
speed above the maximum threshold (2000 rpm), the
PCM will not store a DTC.
There are several operating conditions for which
the PCM monitors and sets DTC's. Refer to Moni-
tored Systems, Components, and Non-Monitored Cir-
cuits in this section.
Technicians must retrieve stored DTC's by connect-
ing the DRB scan tool (or an equivalent scan tool) to
the 16±way data link connector (Fig. 3).
NOTE: Various diagnostic procedures may actually
cause a diagnostic monitor to set a DTC. For
instance, pulling a spark plug wire to perform a
spark test may set the misfire code. When a repair
is completed and verified, connect the DRB scan
tool to the 16±way data link connector to erase all
DTC's and extinguish the MIL.
OPERATION - DIESEL
The PCM and ECM monitor many different cir-
cuits in the powertrain system. If the ECM or PCM
senses a problem with a monitored circuit often
enough to indicate an actual problem, it stores a
Diagnostic Trouble Code (DTC) in the ECM's or
PCM's memory. With certain DTC's, if the problem is
repaired or ceases to exist, the ECM or PCM cancels
the code after 40 warm-up cycles. Certain other
DTC's may be cancelled after 1 or 2 good ªtripsº.
Refer to Trip Definition. DTC's that affect vehicle
emissions illuminate the Malfunction Indicator Lamp
(MIL). The MIL is displayed as an engine icon
(graphic) on the instrument panel. Refer to Malfunc-
tion Indicator Lamp.
Fig. 3 16-WAY DATA LINK CONNECTOR
1 - DATA LINK CONNECTOR
25 - 20 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)

AIR INJECTION
TABLE OF CONTENTS
page page
AIR INJECTION
DESCRIPTION - AIR INJECTION SYSTEM....26
OPERATION - AIR INJECTION SYSTEM......28
SPECIFICATIONS
TORQUE - AIR INJECTION SYSTEM.......29
AIR INJECTION PUMP
DESCRIPTION.........................29
OPERATION...........................29
DIAGNOSIS AND TESTING - AIR INJECTION
PUMP..............................29
REMOVAL.............................30INSTALLATION.........................30
AIR PUMP FILTER
REMOVAL.............................30
INSTALLATION.........................30
ONE WAY CHECK VALVE
DESCRIPTION.........................31
OPERATION...........................31
DIAGNOSIS AND TESTING - ONE-WAY
CHECK VALVE........................31
REMOVAL.............................31
INSTALLATION.........................31
AIR INJECTION
DESCRIPTION - AIR INJECTION SYSTEM
The air injection system (Fig. 1), (Fig. 2) or (Fig. 3)
is used on 5.9L V-8 and 8.0L V-10 heavy duty cycle
(HDC) gas powered engines only. The air injection
system consists of:
²A belt-driven air injection (AIR) pump²Two air pressure relief valves
²Rubber connecting air injection hoses with
clamps
²Metal connecting air tubes
²Two one-way check valves
²A replaceable injection pump air filter (8.0L V-10
engine only)
25 - 26 AIR INJECTIONBR/BE

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)

SPECIFICATIONS
TORQUE - AIR INJECTION SYSTEM
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Air Pump Filter Housing
Nut18
Air Pump Mounting Bolts 40 30
Air Pump Pulley Mounting
Bolts11 105
One-Way Check Valve to
Catalyst Tube33 25
AIR INJECTION PUMP
DESCRIPTION
The air pump is mounted on the front of the
engine and driven by a belt connected to the crank-
shaft pulley (Fig. 4) .
OPERATION
Refer to Air Injection System Description and
Operation for information.
DIAGNOSIS AND TESTING - AIR INJECTION
PUMP
The air injection system and air injection
pump is not completely noiseless.Under normal
conditions, noise rises in pitch as engine speed
increases. To determine if excessive noise is fault of
air injection system, disconnect accessory drive belt
and temporarily operate engine.Do not allow
engine to overheat when operating without
drive belt.
CAUTION: Do not attempt to lubricate the air injec-
tion pump. Oil in the pump will cause rapid deteri-
oration and failure.
Fig. 4 Air Injection Pump MountingÐTypical
1 - PUMP PULLEY
2 - AIR PUMP
3 - AUTOMATIC BELT TENSIONER
4 - PUMP MOUNTING BOLTS (2)
5 - PULLEY BOLTS
BR/BEAIR INJECTION 25 - 29
AIR INJECTION (Continued)

EXCESSIVE BELT NOISE1. Loose belt or defective automatic
belt tensioner.1. Refer to Cooling System.
2. Seized pump. 2. Replace pump.
EXCESSIVE PUMP NOISE
CHIRPING1. Insufficient break-in. 1. Recheck for noise after 1600 km
(1,000 miles) of operation.
EXCESSIVE PUMP NOISE
CHIRPING, RUMBLING, OR
KNOCKING1. Leak in hose. 1. Locate source of leak using soap
solution and correct.
2. Loose hose. 2. Reassemble and replace or tighten
hose clamp.
3. Hose touching other engine parts. 3. Adjust hose position.
4. Relief valve inoperative. 4. Replace relief valve.
5. Check valve inoperative. 5. Replace check valve.
6. Pump mounting fasteners loose. 6. Tighten mounting screws as
specified.
7. Pump failure. 7. Replace pump.
NO AIR SUPPLY.
ACCELERATE ENGINE TO
1500 RPM AND OBSERVE
AIR FLOW FROM HOSES. IF
FLOW INCREASES AS
RPM'S INCREASE, PUMP IS
FUNCTIONING NORMALLY.
IF NOT, CHECK POSSIBLE
CAUSE.1. Loose drive belt. 1. Refer to Cooling System.
2. Leaks in supply hose. 2. Locate leak and repair or replace as
required.
3. Leak at fitting(s). 3. Tighten and replace clamps.
4. Check valve inoperative. 4. Replace check valve.
5. Plugged inlet air filter (8.0L). 5. Replace filter
REMOVAL
The air injection pump does not have any internal
serviceable parts.
(1) Disconnect both of the hoses (tubes) at the air
injection pump.
(2) Loosen, but do not remove at this time, the
three air pump pulley mounting bolts (Fig. 4).
(3) Relax the automatic belt tensioner and remove
the engine accessory drive belt. Refer to Cooling Sys-
tem. See Belt Removal/Installation.
(4) Remove the three air pump pulley bolts and
remove pulley from pump.
(5) Remove the two air pump mounting bolts (Fig.
4) and remove pump from mounting bracket.
INSTALLATION
(1) Position air injection pump to mounting
bracket.
(2) Install two pump mounting bolts to mounting
bracket. Tighten bolts to 40 N´m (30 ft. lbs.) torque.
(3) Install pump pulley and three mounting bolts.
Tighten bolts finger tight.
(4) Relax tension from automatic belt tensioner
and install drive belt. Refer to Cooling System. See
Belt Removal/Installation.(5) Tighten pump pulley bolts to 11 N´m (105 in.
lbs.) torque.
(6) Install hoses and hose clamps at pump.
AIR PUMP FILTER
REMOVAL
The air filter for the air injection pump is located
inside a housing located in right-front side of engine
compartment (Fig. 3) . A rubber hose connects the fil-
ter housing to air injection pump. The filter is used
with 8.0L V-10 engines only.
(1) Remove rubber tubes at filter housing.
(2) Remove filter housing mounting nut and
remove housing.
(3) Remove lid from filter housing (snaps off).
(4) Remove filter from housing.
INSTALLATION
The air filter for the air injection pump is located
inside a housing located in right-front side of engine
compartment (Fig. 3) . A rubber hose connects the fil-
ter housing to air injection pump. The filter is used
with 8.0L V-10 engines only.
25 - 30 AIR INJECTIONBR/BE
AIR INJECTION PUMP (Continued)

(1) Clean inside of housing and lid before install-
ing new filter.
(2) Install filter into housing.
(3) Install lid to filter housing (snaps on).
(4) Position filter housing to fender.
(5) Install mounting nut and tighten to 11 N´m (8
ft. lbs.) torque.
(6) Install rubber tubes and cap at filter housing.
ONE WAY CHECK VALVE
DESCRIPTION
For air injection systems:A pair of one-way
check valves is used with the air injection system.
The check valves (Fig. 1) are located on each of the
air injection downstream tubes.
OPERATION
Each one-way check valve has a one-way dia-
phragm which prevents hot exhaust gases from back-
ing up into the air injection hose and air injection
pump. The check valve will protect the system if theair injection pump belt fails, an air hose ruptures or
exhaust system pressure becomes abnormally high.
DIAGNOSIS AND TESTING - ONE-WAY CHECK
VALVE
The one-way check valves are not repairable. To
determine condition of valve, remove the rubber air
tube from the inlet side of each check valve. Start the
engine. If exhaust gas is escaping through the inlet
side of check valve, it must be replaced.
REMOVAL
(1) Remove the hose clamp at inlet side of valve.
(2) Remove hose from valve.
(3) Remove valve from catalyst tube (unscrew).To
prevent damage to catalyst tube, a backup
wrench must be used on the tube.
INSTALLATION
(1) Install valve to catalyst tube. Tighten to 33
N´m (25 ft. lbs.) torque.
(2) Install hose and hose clamp to valve.
BR/BEAIR INJECTION 25 - 31
AIR PUMP FILTER (Continued)

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)