fuel cap CHRYSLER CARAVAN 2002 Owner's Manual
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Page 1477 of 2399
prevent damage. Replace the injector clip if it is dam-
aged.
(5) Repeat for remaining injectors.
REMOVAL - 3.3/3.8L
(1) Disconnect the negative battery cable.
(2) Remove the Intake Manifold, (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL)
(3) Disconnect injector wiring connector from injec-
tor.
(4) Position fuel rail assembly so that the fuel
injectors are easily accessible (Fig. 12).
(5) Rotate injector and pull injector out of fuel rail.
The clip will stay on the injector.
(6) Check injector O-ring for damage. If O-ring is
damaged, it must be replaced. If injector is reused, a
protective cap must be installed on the injector tip to
prevent damage. Replace the injector clip if it is dam-
aged.
(7) Repeat for remaining injectors.
INSTALLATION
INSTALLATION - 2.4L
The fuel rail must be removed first. Refer to Fuel
Injector Rail Removal in this section.(1) Before installing an injector the rubber O-ring
must be lubricated with a drop of clean engine oil to
aid in installation.
(2) Install injector clip by sliding open end into the
top slot of the injector. The edge of the receiver cup
will slide into the side slots of clip.
(3) Install injector top end into fuel rail receiver
cap. Be careful not to damage O-ring during installa-
tion (Fig. 13).
(4) Repeat steps for remaining injectors.
(5) Connect fuel injector wiring.
INSTALLATION - 3.3/3.8L
(1) Before installing an injector the rubber O-ring
must be lubricated with a drop of clean engine oil to
aid in installation.
(2) Install injector clip by sliding open end into the
top slot of the injector. The edge of the receiver cup
will slide into the side slots of clip (Fig. 12).
(3) Install injector top end into fuel rail receiver
cap. Be careful not to damage O-ring during installa-
tion (Fig. 12).
(4) Repeat steps for remaining injectors.
(5) Install fuel rail, refer to Fuel Rail in the Fuel
Delivery section.
(6) Connect fuel injector wiring.
(7) Install the Intake Manifold, (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION)
(8) Connect the negative battery cable.
Fig. 12 FUEL INJECTOR AND RAIL TYPICAL
1 - FUEL RAIL ASSEMBLY
2 - FUEL INJECTOR
3 - FUEL RAIL RECEIVER
Fig. 13 SERVICING FUEL INJECTOR TYPICAL
1 - FUEL INJECTOR
2 - LOCKING SLOT
3 - FUEL RAIL RECEIVER CUP
14 - 26 FUEL INJECTIONRS
FUEL INJECTOR (Continued)
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Page 1482 of 2399
The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 22).
OPERATION
A single sensor ground is used for all O2 sensors (2
senors on 4 cyl. vehicles and 4 sensors on 6 cyl. vehi-
cles).
As vehicles accumulate mileage, the catalytic con-
vertor deteriorates. The deterioration results in a
less efficient catalyst. To monitor catalytic convertor
deterioration, the fuel injection system uses two
heated oxygen sensors. One sensor upstream of the
catalytic convertor, one downstream of the convertor.
The PCM compares the reading from the sensors to
calculate the catalytic convertor oxygen storage
capacity and converter efficiency. Also, the PCM uses
the upstream heated oxygen sensor input when
adjusting injector pulse width.
When the catalytic converter efficiency drops below
emission standards, the PCM stores a diagnostic
trouble code and illuminates the malfunction indica-
tor lamp (MIL).
The O2 sensors produce voltages from 0 to 1 volt,
depending upon the oxygen content of the exhaust
gas. When a large amount of oxygen is present
(caused by a lean air/fuel mixture, can be caused by
misfire and exhaust leaks), the sensors produces a
low voltage. When there is a lesser amount of oxygen
present (caused by a rich air/fuel mixture, can be
caused by internal engine problems) it produces a
higher voltage. By monitoring the oxygen content
and converting it to electrical voltage, the sensors act
as a rich-lean switch.The oxygen sensors are equipped with a heating
element that keeps the sensors at proper operating
temperature during all operating modes. Maintaining
correct sensor temperature at all times allows the
system to enter into closed loop operation sooner.
Also, it allows the system to remain in closed loop
operation during periods of extended idle.
In Closed Loop operation the PCM monitors the O2
sensors input (along with other inputs) and adjusts
the injector pulse width accordingly. During Open
Loop operation the PCM ignores the O2 sensor input.
The PCM adjusts injector pulse width based on pre-
programmed (fixed) values and inputs from other
sensors.
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to both the upstream and downstream
heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating ele-
ments reduce the time required for the sensors to
reach operating temperature. The PCM uses pulse
width modulation to control the ground side of the
heater to regulate the temperature on 4 cyl.
upstream O2 heater only. All other 4 cyl. and 6 cyl.
O2 heaters do not use pulse width modulation.
UPSTREAM OXYGEN SENSOR
The input from the upstream heated oxygen sensor
tells the PCM the oxygen content of the exhaust gas.
Based on this input, the PCM fine tunes the air-fuel
ratio by adjusting injector pulse width.
The sensor input switches from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air-fuel mixture), the
sensor produces voltage as low as 0.1 volt. When
there is a lesser amount of oxygen present (rich air-
fuel mixture) the sensor produces a voltage as high
as 1.0 volt. By monitoring the oxygen content and
converting it to electrical voltage, the sensor acts as
a rich-lean switch.
The heating element in the sensor provides heat to
the sensor ceramic element. Heating the sensor
allows the system to enter into closed loop operation
sooner. Also, it allows the system to remain in closed
loop operation during periods of extended idle.
In Closed Loop, the PCM adjusts injector pulse
width based on the upstream heated oxygen sensor
input along with other inputs. In Open Loop, the
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor input is
used to detect catalytic convertor deterioration. As
the convertor deteriorates, the input from the down-
Fig. 22 O2 SENSOR DOWNSTREAM 1/2 - 2.4/3.3/
3.8L
RSFUEL INJECTION14-31
O2 SENSOR (Continued)
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FUEL SYSTEM
TABLE OF CONTENTS
page page
FUEL SYSTEM 2.5L TURBO DIESEL
DESCRIPTION - DIESEL FUEL DELIVERY
SYSTEM.............................1
WARNING - HIGH FUEL SYSTEM PRESSURE . . 1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AIR IN FUEL
SYSTEM.............................1
DIAGNOSIS AND TESTING - FUEL SUPPLY
RESTRICTIONS........................1
STANDARD PROCEDURE
STANDARD PROCEDURES - DRAINING
WATER FROM FUEL FILTER..............2STANDARD PROCEDURE - FUEL SYSTEM
AIR PURGE...........................2
STANDARD PROCEDURES - CLEANING
FUEL SYSTEM COMPONENTS............2
SPECIFICATIONS - TORQUE...............3
FUEL DELIVERY..........................4
FUEL INJECTION........................11
FUEL SYSTEM 2.5L TURBO
DIESEL
DESCRIPTION - DIESEL FUEL DELIVERY
SYSTEM
The fuel system on the 2.5L Common Rail Diesel
Engine uses a fuel injection pump and an Electronic
Control Module (ECM).
The fuel delivery system consists of the:
²Accelerator pedal
²Air cleaner housing/element
²Fuel filter/water separator
²Fuel heater
²Fuel heater relay
²Fuel transfer (lift) pump
²Fuel injection pump
²Fuel injectors
²Fuel tank
²Fuel tank filler/vent tube assembly
²Fuel tank filler tube cap
²Fuel tank module containing the rollover valve
and a fuel gauge sending unit (fuel level sensor).
²Fuel tubes/lines/hoses
²High-pressure fuel injector lines
²Low-pressure fuel supply lines
²Low-pressure fuel return line
²Overflow valve
²Quick-connect fittings
²Water draining
WARNING - HIGH FUEL SYSTEM PRESSURE
WARNING:: THE INJECTION PUMP SUPPLIES HIGH-
PRESSURE FUEL TO EACH INDIVIDUAL INJECTOR
THROUGH HIGH-PRESSURE LINES. FUEL UNDERTHIS AMOUNT OF PRESSURE CAN PENETRATE
SKIN AND CAUSE PERSONAL INJURY. WEAR
SAFETY GOGGLES AND ADEQUATE PROTECTIVE
CLOTHING. AVOID CONTACT WITH FUEL SPRAY
WHEN BLEEDING HIGH-PRESSURE FUEL LINES.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AIR IN FUEL
SYSTEM
Air will enter the fuel system whenever fuel supply
lines, separator filters, injection pump, high-pressure
lines or injectors are removed or disconnected. Air
trapped in the fuel system can result in hard start-
ing, a rough running engine, engine misfire, low
power, excessive smoke and fuel knock. After service
is performed, air must be bled from the system
before starting the engine.
Inspect the fuel system from the fuel tank to the
injectors for loose connections. Leaking fuel is an
indicator of loose connections or defective seals. Air
can also enter the fuel system between the fuel tank
and the transfer pump. Inspect the fuel tank and fuel
lines for damage that might allow air into the sys-
tem.
DIAGNOSIS AND TESTING - FUEL SUPPLY
RESTRICTIONS
LOW-PRESSURE LINES
Fuel supply line restrictions or a defective fuel
transfer pump can cause starting problems and pre-
vent engine from accelerating. The starting problems
include; low power and/or white fog like exhaust.
RGFUEL SYSTEM14a-1
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Test all fuel supply lines for restrictions or block-
age. Flush or replace as necessary. Bleed fuel system
of air once a fuel supply line has been replaced. Refer
to Air Bleed Procedure for procedures.
To test for fuel line restrictions, a vacuum restric-
tion test may be performed.
HIGH-PRESSURE LINES
Restricted (kinked or bent) high-pressure lines can
cause starting problems, poor engine performance,
engine mis-fire and white smoke from exhaust.
Examine all high-pressure lines for any damage.
Each radius on each high-pressure line must be
smooth and free of any bends or kinks.
Replace damaged, restricted or leaking high-pres-
sure fuel lines with correct replacement line.
CAUTION: High pressure 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 line is kinked or bent, it must be
replaced. Use only recommended lines when
replacement of high-pressure fuel line is necessary.
STANDARD PROCEDURE
STANDARD PROCEDURES - DRAINING WATER
FROM FUEL FILTER
Refer to Fuel Filter/Water Separator removal/in-
stallation for procedures.
STANDARD PROCEDURE - FUEL SYSTEM AIR
PURGE
(1) Remove engine cover (Refer to 9 - ENGINE
COVER - REMOVAL).
(2) Remove cap from air purge fitting on the fuel
supply line. This fitting is located just behind the
alternator (Fig. 1).
(3) Attach a hose of about 1 or 2 meters to this fit-
ting using an appropriate connector.
(4) Direct the end of the hose into an appropriate
fuel container.
(5) Turn the ignition to the ªONº position,Do not
crank the engine.Keep key on until about 1 liter of
fuel has been pumped into the container.
(6) While keeping end of hose below fuel level in
conatiner, turn the ignition ªOFFº.
(7) Remove hose from air purge fitting on the fuel
supply line and replace cap.
(8) Install engine cover (Refer to 9 - ENGINE
COVER - INSTALLATION).
STANDARD PROCEDURES - CLEANING FUEL
SYSTEM COMPONENTS
CAUTION: Cleanliness cannot be overemphasized
when handling or replacing diesel fuel system com-
ponents. This especially includes the fuel injectors,
high-pressure fuel lines, fuel rail, and fuel injection
pump. Very tight tolerances are used with these
parts. Dirt contamination could cause rapid part
wear and possible plugging of fuel injector nozzle
tip holes. This in turn could lead to possible engine
misfire. Always wash/clean any fuel system compo-
nent thoroughly before disassembly and then air
dry. Cap or cover any open part after disassembly.
Before assembly, examine each part for dirt, grease
or other contaminants and clean if necessary. When
installing new parts, lubricate them with clean
engine oil or clean diesel fuel only.
Fig. 1 AIR PURGE VALVE
1 - AIR PURGE VALVE CAP
2 - AIR PURGE VALVE
3 - ALTERNATOR
4 - ENGINE FRONT COVER
14a - 2 FUEL SYSTEMRG
FUEL SYSTEM 2.5L TURBO DIESEL (Continued)
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Page 1493 of 2399
Refer to the maintenance schedules for the recom-
mended fuel filter replacement intervals.
For draining of water from canister, refer to Fuel
Filter/Water Separator Removal/Installation section.
A Water-In-Fuel (WIF) sensor is part of the fuel fil-
ter cap. Refer to Water-In-Fuel Sensor Description/
Operation.
The fuel heater is installed into the filter/separator
housing above the fuel filter. Refer to Fuel Heater
Description/Operation.
FUEL LINES
DESCRIPTION
DESCRIPTION
All fuel lines up to the fuel injection pump are con-
sidered low-pressure. This includes the fuel lines
from: the fuel tank to the fuel transfer pump, and
the fuel transfer pump to the fuel injection pump.
The fuel return lines and the fuel drain lines are also
considered low-pressure lines. High-pressure lines
are used between the fuel injection pump and the
fuel injectors. Also refer to High-Pressure Fuel Lines
Description/Operation.
DESCRIPTION - HIGH PRESSURE FUEL LINES
The high-pressure fuel lines are the 4 lines located
between the fuel injection pump and the fuel injec-
torsctor tubes. All other fuel lines are considered low-
pressure lines.
OPERATION - HIGH PRESSURE FUEL LINES
CAUTION: The high-pressure fuel lines cannot con-
tact 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 recom-
mended lines when replacement of high-pressure
fuel line is necessary.
High-pressure fuel lines deliver fuel under
extremely high pressure from the injection pump to
the fuel injectors. The lines expand and contract from
the high-pressure fuel pulses generated during the
injection process. 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.
WARNING: USE EXTREME CAUTION WHEN
INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH
A SHEET OF CARDBOARD. HIGH FUEL INJECTIONPRESSURE CAN CAUSE PERSONAL INJURY IF
CONTACT IS MADE WITH THE SKIN.
DIAGNOSIS AND TESTING - HIGH PRESSURE
FUEL LINES
High-pressure fuel line leaks can cause starting
problems and poor engine performance.
WARNING: DUE TO EXTREME FUEL PRESSURES,
USE EXTREME CAUTION WHEN INSPECTING FOR
HIGH-PRESSURE FUEL LEAKS. DO NOT GET YOUR
HAND NEAR A SUSPECTED LEAK. 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.
Start the engine. Move the cardboard over the
high-pressure fuel lines and check for fuel spray onto
the cardboard (Fig. 4). If a high-pressure line connec-
tion is leaking, bleed the system and tighten the con-
nection. Refer to the Air Bleed Procedure in this
group for procedures. Replace damaged, restricted or
leaking high-pressure fuel lines with the correct
replacement line.
Fig. 4 Typical Test for Leaks with Cardboard
1 - HIGH-PRESSURE LINE
2 - CARDBOARD
3 - FITTING
14a - 6 FUEL DELIVERYRG
FUEL FILTER / WATER SEPARATOR (Continued)
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door temperature drops. After checking the air
pressure, replace valve cap finger tight.
Inflation pressures specified on the Tire Inflation
Pressure Label are always the cold inflation pressure
of the tire. Cold inflation pressure is obtained after
the vehicle has not been operated for at least 3
hours, or the vehicle is driven less than one mile
after being inoperative for 3 hours. Tire inflation
pressures may increase from 2 to 6 pounds persquare inch (psi) (14 to 41 kPa) during operation. Do
not reduce this normal pressure buildup.
Improper inflation can cause:
²Uneven wear patterns
²Reduced tread life
²Reduced fuel economy
²Unsatisfactory ride
²The vehicle to drift.
WARNING: OVER OR UNDER INFLATED TIRES CAN
AFFECT VEHICLE HANDLING. THE TIRE CAN FAIL
SUDDENLY, RESULTING IN LOSS OF VEHICLE
CONTROL.
Under inflation causes rapid shoulder wear, tire
flexing, and can result in tire failure (Fig. 25).
Fig. 23 Tire Wear Patterns
Fig. 24 Tread Wear Indicators
1 - TREAD ACCEPTABLE
2 - TREAD UNACCEPTABLE
3 - WEAR INDICATOR
Fig. 25 Under Inflation Wear
1 - THIN TIRE TREAD AREAS
22 - 16 TIRES/WHEELSRS
TIRES (Continued)
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PLUMBING - FRONT
WARNING
WARNING
WARNING: DO NOT OPERATE DCHA IN AN
ENCLOSED AREA SUCH AS A GARAGE THAT
DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA'S EXHAUST WHEN
OPERATING THE DCHA. FAILURE TO FOLLOW
THESE INSTRUCTION MAY RESULT IN PERSONAL
INJURY OR DEATH.
ALLOW THE DCHA ASSEMBLY TO COOL BEFORE
PERFORMING A COMPONENT INSPECTION/RE-
PAIR/REPLACEMENT. FAILURE TO FOLLOW THESE
INSTRUCTIONS MY RESULT IN PERSONAL INJURY.
VERIFY THAT ALL DCHA FUEL LINES ARE
SECURELY FASTENED TO THEIR RESPECTIVE
COMPONENTS BEFORE THIS PROCEDURE.
WARNING
WARNING:: THE ENGINE COOLING SYSTEM IS
DESIGNED TO DEVELOP INTERNAL PRESSURES
OF 97 TO 123 KILOPASCALS (14 TO 18 POUNDS
PER SQUARE INCH). DO NOT REMOVE OR
LOOSEN THE COOLANT PRESSURE CAP, CYLIN-
DER BLOCK DRAIN PLUGS, RADIATOR DRAIN,
RADIATOR HOSES, HEATER HOSES, OR HOSE
CLAMPS WHILE THE SYSTEM IS HOT AND UNDER
PRESSURE. FAILURE TO OBSERVE THIS WARNING
CAN RESULT IN SERIOUS BURNS FROM THE
HEATED ENGINE COOLANT. ALLOW THE VEHICLE
TO COOL FOR A MINIMUM OF 15 MINUTES
BEFORE OPENING THE COOLING SYSTEM FOR
SERVICE.
WARNING: THE ENGINE COOLING SYSTEM CON-
TAINS ANTIFREEZE. ANTIFREEZE IS AN ETHYLENE
GLYCOL BASED COOLANT AND IS HARMFUL IF
SWALLOWED OR IF THE VAPORS ARE INHALED. IF
SWALLOWED, DRINK TWO GLASSES OF WATER
AND INDUCE VOMITING. IF VAPORS ARE INHALED,
MOVE TO AN AREA FOR FRESH AIR. SEEK MEDI-
CAL ATTENTION IMMEDIATELY. DO NOT STORE IN
OPEN OR UNMARKED CONTAINERS. WASH SKIN
AND CLOTHING THOROUGHLY AFTER COMING IN
CONTACT WITH ETHYLENE GLYCOL. KEEP OUT
OF REACH OF CHILDREN.
WARNING: DISPOSE OF ETHYLENE GLYCOL
BASED COOLANT PROPERLY. CONTACT YOURDEALER OR A LOCAL GOVERNMENT AGENCY FOR
THE LOCATION OF AN APPROVED ETHYLENE GLY-
COL COLLECTION AND/OR RECYCLING CENTER IN
YOUR AREA.
WARNING - A/C PLUMBING
WARNING:: THE AIR CONDITIONING SYSTEM CON-
TAINS REFRIGERANT UNDER HIGH PRESSURE.
SEVERE PERSONAL INJURY MAY RESULT FROM
IMPROPER SERVICE PROCEDURES. REPAIRS
SHOULD ONLY BE PERFORMED BY QUALIFIED
SERVICE PERSONNEL.
WARNING: AVOID BREATHING THE REFRIGERANT
AND REFRIGERANT OIL VAPOR OR MIST. EXPO-
SURE MAY IRRITATE THE EYES, NOSE, AND/OR
THROAT. WEAR EYE PROTECTION WHEN SERVIC-
ING THE AIR CONDITIONING REFRIGERANT SYS-
TEM. SERIOUS EYE INJURY CAN RESULT FROM
DIRECT CONTACT WITH THE REFRIGERANT. IF
EYE CONTACT OCCURS, SEEK MEDICAL ATTEN-
TION IMMEDIATELY.
WARNING: DO NOT EXPOSE THE REFRIGERANT
TO OPEN FLAME. POISONOUS GAS IS CREATED
WHEN REFRIGERANT IS BURNED. AN ELEC-
TRONIC LEAK DETECTOR IS RECOMMENDED.
WARNING: IF ACCIDENTAL SYSTEM DISCHARGE
OCCURS, VENTILATE THE WORK AREA BEFORE
RESUMING SERVICE. LARGE AMOUNTS OF
REFRIGERANT RELEASED IN A CLOSED WORK
AREA WILL DISPLACE THE OXYGEN AND CAUSE
SUFFOCATION.
WARNING: THE EVAPORATION RATE OF R-134a
REFRIGERANT AT AVERAGE TEMPERATURE AND
ALTITUDE IS EXTREMELY HIGH. AS A RESULT,
ANYTHING THAT COMES IN CONTACT WITH THE
REFRIGERANT WILL FREEZE. ALWAYS PROTECT
THE SKIN OR DELICATE OBJECTS FROM DIRECT
CONTACT WITH THE REFRIGERANT.
WARNING: THE R-134a SERVICE EQUIPMENT OR
THE VEHICLE REFRIGERANT SYSTEM SHOULD
NOT BE PRESSURE TESTED OR LEAK TESTED
WITH COMPRESSED AIR. SOME MIXTURES OF AIR
AND R-134a HAVE BEEN SHOWN TO BE COMBUS-
TIBLE AT ELEVATED PRESSURES. THESE MIX-
TURES ARE POTENTIALLY DANGEROUS, AND MAY
RESULT IN FIRE OR EXPLOSION CAUSING INJURY
OR PROPERTY DAMAGE.
24 - 60 PLUMBING - FRONTRS
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Page 2355 of 2399
(4) Connect the electrical connector to the fuel
pump by depressing the integral spring and pushing
the connector towards the dosing pump. Pull the con-
nector towards the heater to verify the installation.
(5) Verify function of the heater.
FUEL LINE
STANDARD PROCEDURE - CLEANING
(1) Remove the cabin heater fuel line(Refer to 24 -
HEATING & AIR CONDITIONING/CABIN HEAT-
ER/FUEL LINE - REMOVAL).
(2) With cabin heater line removed from vehicle
place a shop cloth on the fuel tank end of the fuel
line to catch any residue, then apply a small amount
of air pressure to the other end of the fuel line.
(3) Check to see if air pressure is coming from the
tank end of the line. If pressure is flowing unre-
stricted the line is clean.
(4) If the line shows any signs of being restricted
after air pressure is applied, then the fuel line should
be replaced.
(5) Install the cabin heater line(Refer to 24 -
HEATING & AIR CONDITIONING/CABIN HEAT-
ER/FUEL LINE - INSTALLATION).
(6) Verify function of the heater.
REMOVAL
(1) Elevate vehicle on a lift taking note of the
heater exhaust tube flexible section.
(2) Remove clamps on dosing pump end of fuel line
and separate line from pump (Fig. 3).
NOTE: Have an approved fuel holding device ready
to capture any diesel fuel that drains from fuel line
or heater unit.
(3) Remove clamp from fuel line at fuel tank con-
nection and separate line from tank.
(4) Remove any retaining clips and remove line
from vehicle.
INSTALLATION
WARNING: DO NOT OPERATE THE DCHA IN AN
ENCLOSED AREA SUCH AS A GARAGE THAT
DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA'S EXHAUST WHEN
OPERATING THE DCHA. FAILURE TO FOLLOW
THESE INSTRUCTIONS MAY RESULT IN PERSONAL
INJURY OR DEATH.
Fig. 2 Dosing Pump Fuel Line
1 - Fuel Line
2 - Retaining Clamps3 - Dosing Pump
4 - Heater Unit Air Intake Pipe
24 - 112 DIESEL SUPPLEMENTAL HEATER - DCHA - BUXRS
FUEL DOSING PUMP (Continued)
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Page 2357 of 2399
(7) With the DRBIIItin Cabin Heater, select Sys-
tem Tests and Dosing Pump Prime. Allow the Dosing
Pump to run for the full 45 second cycle time. When
the 45 second cycle is complete, press Page Back on
the DRBIIItkey pad to exit the Dosing Pump Prime.
The Dosing Pump priming procedure is now com-
plete.
HEATER UNIT
REMOVAL
WARNING: ALLOW THE DCHA TO COOL BEFORE
PERFORMING A COMPONENT INSPECTION/REPAIR
OR REPLACEMENT. FAILURE TO FOLLOW THESE
INSTRUCTIONS MAY RESULT IN PERSONAL
INJURY.
WARNING: ALLOW THE EXHAUST SYSTEM TO
COOL BEFORE PERFORMING A COMPONENT
INSPECTION/REPAIR OR REPLACEMENT. FAILURE
TO FOLLOW THESE INSTRUCTION MAY RESULT IN
PERSONAL INJURY.
(1) Elevate the vehicle on a hoist/lift taking note of
heater exhaust tube flexible section.
(2) Drain cooling system(Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Carefully open one hose to the underbody tube
assembly and drain the remaining coolant. A salvage
hose is a good idea to control the residual coolant, as
flow will occur from both the heater and the hose and
tube assemblies.
(4) Remove the second hose from the underbody
hose and tube assembly.
(5) Loosen the hose and tube assembly from the
toe-board cross member at two locations.
(6) Disconnect the electrical connector from the
body harness near the toe board cross member and
rail.
(7) Remove the wiring harness from the toe board
cross member(Refer to 24 - HEATING & AIR CON-
DITIONING/CABIN HEATER/HEATER UNIT -
REMOVAL).
(8) Open the fuel fill cap. Disconnect the rubber
fuel hose between the body tube assembly and the
fuel pump nipple at the body tube joint. A minimal
amount of fuel may flow from the open port.
NOTE: Utilize an approved fuel storage container to
catch any residual fuel.
(9) Loosen the two M8 fasteners at the rail. Take
care to notice that the exhaust tube bracket tab is on
top of the heater bracket.(10) Remove the heater exhaust tube flex section
from the exhaust tube by loosening the M6 bolt of
the clamp assembly. Remove the hose from the
exhaust tube. Removal of the rail tube assembly may
aid in this service operation.(Refer to 24 - HEATING
& AIR CONDITIONING/CABIN HEATER/EXHAUST
TUBE - REMOVAL).
(11) Remove seat hex nut at the heater mounting
flange to cross member.
(12) Loosen the remaining M6 and M8 fasteners
which mount the exhaust tube assembly to the vehi-
cle.
(a) Install a suitable cabin heater support device
under the cabin heater and secure the cabin heater
to the device.
(13) Loosen the remaining three M6 fasteners to
the cross members.
(14) Remove the loosened fasteners that support
the heater while supporting the weight of the heater.
(15) Swing the unit mounting bracket from
between the exhaust bracket and rail mounting loca-
tion. Drain any residual coolant from the heater unit.
(16) Lower the cabin heater and remove from the
supporting device and place on a suitable work area.
INSTALLATION
(1) Install the unit mounting bracket between the
exhaust bracket and the rail mounting location.
(2) Install the fasteners that support the heater
while supporting the weight of the heater.
(3) Install the three M6 fasteners to the cross
members. Tighten the M6 fasteners to 7 Nm (5 ft.
lbs.).
(4) Tighten the remaining M6 fasteners to 7 Nm (5
ft. lbs.) and the M8 fasteners to 23 Nm (17 ft. lbs.)
which mount the exhaust tube assembly to the vehi-
cle.
(5) Install the seat hex nut at the heater mounting
flange to the cross members. Tighten to 60 Nm (44 ft.
lbs.)
(6) Install the heater exhaust tube flex section to
the exhaust tube by tightening the M6 bolt of the
clamp assembly. Install the hose to the exhaust tube.
(7) Tighten the two M8 fasteners at the rail to 23
Nm (17 ft. lbs.). Taking care so that the exhaust tube
bracket tab is on the top of the heater bracket.
(8) Install the wiring harness(Refer to 24 - HEAT-
ING & AIR CONDITIONING/CABIN HEATER/
HEATER UNIT - INSTALLATION).
(9) Tighten the hose and tube assembly to the toe-
board cross member at two locations.
(10) Install the second hose to the underbody hose
and tube assembly.
(11) Connect the rubber fuel hose between the
body tube assembly and the fuel pump nipple at the
body tube joint. Close the fuel fill cap.
24 - 114 DIESEL SUPPLEMENTAL HEATER - DCHA - BUXRS
FUEL LINE (Continued)
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Page 2363 of 2399
The PCM sends a 5 volt bias to the oxygen sensor
every 1.6 seconds. The PCM keeps it biased for 35
ms each time. As the sensor cools down, the resis-
tance increases and the PCM reads the increase in
voltage. Once voltage has increased to a predeter-
mined amount, higher than when the test started,
the oxygen sensor is cool enough to test heater oper-
ation.
When the oxygen sensor is cool enough, the PCM
energizes the ASD relay. Voltage to the O2 sensor
begins to increase the temperature. As the sensor
temperature increases, the internal resistance
decreases. The PCM continues biasing the 5 volt sig-
nal to the sensor. Each time the signal is biased, the
PCM reads a voltage decrease. When the PCM
detects a voltage decrease of a predetermined value
for several biased pulses, the test passes.
The heater elements are tested each time the
engine is turned OFF if all the enabling conditions
are met. If the monitor fails, the PCM stores a
maturing fault and a Freeze Frame is entered. If two
consecutive tests fail, a DTC is stored. Because the
ignition is OFF, the MIL is illuminated at the begin-
ning of the next key cycle.
Enabling ConditionsÐThe following conditions
must be met for the PCM to run the oxygen sensor
heater test:
²Engine run time of at least 3 minutes
²Engine run time at a predetermind speed and
throttle opening.
²Key OFF power down
²Battery voltage of at least 10 volts
²Sufficient Oxygen Sensor cool down
Pending ConditionsÐThere are not conditions or
situations that prompt conflict or suspension of test-
ing. The oxygen sensor heater test is not run pending
resolution of MIL illumination due to oxygen sensor
failure.
SuspendÐThere are no conditions which exist for
suspending the Heater Monitor.
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. A meltdown of the ceramic core can
cause a reduction of the exhaust passage. This can
increase vehicle emissions and deteriorate engine
performance, driveability and fuel economy.
The catalyst monitor uses dual oxygen sensors
(O2S's) to monitor the efficiency of the converter. The
dual O2S strategy is based on the fact that as a cat-
alyst deteriorates, its oxygen storage capacity and its
efficiency are both reduced. By monitoring the oxy-gen storage capacity of a catalyst, its efficiency 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 converter. The
PCM calculates the A/F mixture from the output of
the O2S. A low voltage indicates high oxygen 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 (check
engine lamp) will be illuminated.
Monitor OperationÐTo monitor catalyst effi-
ciency, the PCM expands the rich and lean switch
points of the heated oxygen sensor. With extended
switch points, the air/fuel mixture runs richer and
leaner to overburden the catalytic converter. Once
the test is started, the air/fuel mixture runs rich and
lean and the O2 switches are counted. A switch is
counted when an oxygen sensor signal goes from
below the lean threshold to above the rich threshold.
The number of Rear O2 sensor switches is divided by
the number of Front O2 sensor switches to determine
the switching ratio.
The test runs for 20 seconds. As catalyst efficiency
deteriorated over the life of the vehicle, the switch
rate at the downstream sensor approaches that of the
upstream sensor. If at any point during the test
period the switch ratio reaches a predetermined
value, a counter is incremented by one. The monitor
25 - 4 EMISSIONS CONTROLRS
EMISSIONS CONTROL (Continued)
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