DIAGNOSIS AND TESTING
REAR A/C EXPANSION VALVE
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
NOTE: The expansion valve should only be tested
following testing of the compressor.
NOTE: Liquid CO
2is required to test the expansion
valve. This material is available from most welding
supply facilities. Liquid CO
2is also available from
companies which service and sell fire extinguish-
ers.
When testing the expansion valve, the work area
and the vehicle temperature must be 21É to 27É C
(70É to 85É F). To test the expansion valve:
(1) Connect a charging station or manifold gauge
set to the refrigerant system service ports. Verify the
refrigerant charge level.
(2) Close all doors, windows and vents to the pas-
senger compartment.
(3) Set the heater-air conditioner controls so that
the compressor is operating, the temperature control
is in the highest temperature position, the mode door
is directing the output to the floor outlets, and the
blower is operating at the highest speed setting.
(4) Start the engine and allow it to idle at 1000
rpm. After the engine has reached normal operating
temperature, allow the passenger compartment to
heat up. This will create the need for maximum
refrigerant flow into the evaporator.
(5) If the refrigerant charge is sufficient, the dis-
charge (high pressure) gauge should read 965 to 1655
kPa (140 to 240 psi). The suction (low pressure)
gauge should read 140 kPa to 207 kPa (20 psi to 30
psi). If OK, go to Step 6. If not OK, replace the faulty
expansion valve.
WARNING: PROTECT THE SKIN AND EYES FROM
EXPOSURE TO LIQUID CO
2. PERSONAL INJURY
CAN RESULT.
(6)
If the suction (low pressure) gauge reads within
the specified range, freeze the expansion valve control
head for 30 seconds using liquid CO
2or another suit-
able super-cold material.Do not spray R-134a or
R-12 refrigerant on the expansion valve controlhead for this test.
The suction (low pressure) gauge
reading should drop by 10 psi. If OK, go to Step 7 If
not OK, replace the faulty expansion valve.
(7) Allow the expansion valve control head to thaw.
The suction (low pressure) gauge reading should sta-
bilize at 140 kPa to 240 kPa (20 psi to 30 psi). If not
OK, replace the faulty expansion valve.
(8) When expansion valve testing is complete, test
the overall air conditioner performance (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - A/C PERFORMANCE TEST).
Remove all test equipment before returning the vehi-
cle to service.
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - A/C PLUMBING), (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT - CAUTION - A/C PLUMBING), and (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - HEATER PLUMBING).
(1) Remove the rear HVAC housing from the vehi-
cle (Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL).
(2) Carefully remove the foam insulator wrap from
the rear expansion valve.
(3) Remove the rear evaporator line extension from
the expansion valve (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - REAR/EVAPORA-
TOR - REMOVAL - EVAPORATOR LINE EXTEN-
SION).
(4) Remove the two screws that secure the expan-
sion valve to the evaporator tube sealing plate.
(5) Remove the expansion valve from the evapora-
tor tubes.
(6) Remove the seals from the evaporator tube fit-
tings and discard.
(7) Install plugs in, or tape over the opened evap-
orator tube fittings and both expansion valve ports.
INSTALLATION
(1) Remove the tape or plugs from the rear A/C
evaporator tube fittings and both expansion valve
ports.
(2) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the rear evapora-
tor tube fittings.
(3) Position the expansion valve onto the evapora-
tor tubes.
(4) Install the two screws that secure the rear A/C
expansion valve to the evaporator tube sealing plate.
Tighten the screws to 11 N´m (97 in. lbs.).
RSPLUMBING - REAR24 - 101
A/C EXPANSION VALVE (Continued)
(5) Install the rear evaporator line extension onto
the expansion valve (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - REAR/EVAPORA-
TOR - INSTALLATION - EVAPORATOR LINE
EXTENSION).
(6) Install the foam insulator wrap over the rear
expansion valve.
(7) Install the rear HVAC housing (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - INSTALLATION).
(8) Run the HVAC Cooldown Test to verify proper
operation.
HEATER CORE
DESCRIPTION
The rear heater core is located near the front of
the rear HVAC housing, behind the right rear wheel
house. It is a heat exchanger made of rows of tubes
and fins. One end of the core is fitted with a molded
plastic tank that includes integral heater core inlet
and outlet nipples. The rear heater core can be ser-
viced without removing the rear HVAC housing from
the vehicle.
OPERATION
Engine coolant is circulated through underbody
heater hoses to the rear heater core at all times. As
the coolant flows through the rear heater core, heat
removed from the engine is transferred to the heater
core fins and tubes. Air directed through the heater
core picks up the heat from the heater core fins. The
rear blend door allows control of the rear heater out-
put air temperature by controlling how much of the
air flowing through the rear HVAC housing is
directed through the heater core.
The rear heater core cannot be repaired and, if
faulty or damaged, it must be replaced.
STANDARD PROCEDURE
REAR HEATER CORE FILLING
In its final installed position, the rear heater core
is positioned higher than the radiator fill cap. There-
fore, when the cooling system is drained and refilled,
gravity will not refill the heater core with coolant to
the proper level. This may result in two problems:1.
Insufficient coolant level in the engine cooling sys-
tem, which may result in engine overheating.2.Air
entrapped within the rear heater core, which may
result in insufficient rear heater performance. There
are two methods that may be employed to prevent
these problems:1.Pre-filling of the rear heater core.
2.Thermal cycling of the engine cooling system. Fol-lowing are descriptions of both prevention methods,
as well as a method to verify rear heater perfor-
mance.
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING
FRONT - WARNING - HEATER PLUMBING).
PRE-FILLING
If the rear heater core or the rear HVAC housing
have been removed from the vehicle for service, the
rear heater core may be pre-filled with the proper
engine coolant mixture prior to reconnecting the
heater hoses to the heater core hose fittings.
(1) The heater core should be installed in the rear
HVAC housing, and the rear HVAC housing should
be installed in the vehicle.
(2) Take the proper precautions to protect the car-
peting below the rear heater core from spilled engine
coolant and have absorbent toweling readily avail-
able to mop up any spills.
(3) Insert the small end of an appropriate funnel
into the upper hose fitting of the heater core (Fig. 4).
(4) Carefully pour the proper pre-mixed engine
coolant solution into the rear heater core through a
funnel until coolant begins to appear at the lower
hose fitting of the heater core.
(5) Use absorbent toweling to clean up any engine
coolant spills from the preceding operation.
(6) Reconnect the heater hoses to the rear heater
core (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - REAR/HEATER HOSE - INSTAL-
LATION).
Fig. 4 Pre-Filling Heater Core - Typical
1 - REAR HEATER CORE
24 - 102 PLUMBING - REARRS
A/C EXPANSION VALVE (Continued)
(7) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM REFILL).
THERMAL CYCLING
If the rear heater core was emptied and was not
pre-filled, it will be necessary to thermal cycle the
vehicle at least two times to ensure that the rear
heater core is properly filled.
(1) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM REFILL).
(2) Start the engine and allow it to operate until
the thermostat opens.
(3) Turn the engine off and allow it to cool.
(4) With the engine cold and not running, check
and top off the engine coolant level as necessary
(Refer to 7 - COOLING - STANDARD PROCEDURE
- COOLANT LEVEL CHECK) and (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLANT
- ADDING).
(5) Start the engine and allow it to operate until
the thermostat opens again.
(6) Turn the engine off and allow it to cool down
again.
(7) With the engine cold and not running, check
and top off the engine coolant level as necessary
(Refer to 7 - COOLING - STANDARD PROCEDURE
- COOLANT LEVEL CHECK) and (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLANT
- ADDING).
(8) Check the performance of the rear heater.
Refer to REAR HEATER PERFORMANCE CHECK.
REAR HEATER PERFORMANCE CHECK
Successful completion of the rear heater perfor-
mance check will confirm that the rear heater core is
properly filled with engine coolant. If the check is not
successful, either there is still air trapped in the rear
heater core or the rear heater plumbing is restricted.
This check should be performed with the vehicle in a
shop where the ambient temperature is about 21É C
(70É F).
(1) Start the engine and allow it to idle until it
warms up to normal operating temperature.
(2) Adjust the heater-A/C controls so that the front
heater is turned Off, the rear heater is set for full
Heat, and the rear blower motor is at its highest
speed setting.
(3) Use an accurate test thermometer to measure
the temperature of the air being discharged from the
rear heater outlet located at the base of the right
C-pillar.
(4) Proper discharge air temperature readings
should be from 57É to 63É C (135É to 145É F).REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING
FRONT - WARNING - HEATER PLUMBING).
(1) Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM DRAIN).
(2) Remove the right quarter trim panel and right
D-pillar trim panel from the quarter inner panel
(Refer to 23 - BODY/INTERIOR/QUARTER TRIM
PANEL - REMOVAL).
(3) Remove the rear heater distribution duct from
the right quarter inner panel (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION -
REAR/REAR HEATER DISTRIBUTION DUCT -
REMOVAL).
(4) Remove the screw that secures the back of the
rear HVAC housing to the right D-pillar.
(5) Remove the screw that secures the front of the
rear HVAC housing to the right quarter inner panel.
(6) Take the proper precautions to protect the car-
peting below the rear heater core from spilled engine
coolant and have absorbent toweling readily avail-
able to mop up any spills.
(7) Disconnect the heater hoses at the rear heater
core (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - REAR/HEATER HOSE -
REMOVAL).
(8) Install plugs in, or tape over the opened heater
core fittings and both heater hoses (Fig. 5).
Fig. 5 Rear Heater Core
1 - REAR HVAC HOUSING OUTLET
2 - REAR HVAC UNIT HOUSING
3 - LATCH (4)
4 - REAR HEATER CORE
5 - RIGHT REAR WHEEL HOUSE
6 - REAR HEATER HOSES
RSPLUMBING - REAR24 - 103
HEATER CORE (Continued)
INSTALLATION
(1) Install the front underbody heater inlet and
return hoses by carefully twisting the hoses back and
forth on the underbody tubes, while gently pushing
them onto the end of the tubes.
CAUTION:
DO NOT apply excessive pressure on heater tubes
or connections when removing heater hoses.
Excessive pressure may damage or deform the
tubes, causing an engine coolant leak.
(2) Using spring tension clamp pliers, compress
and slide the clamps that secure each end of the
heater hose over the tubes. Release the clamp when
it is over the tube.
(3) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM REFILL).
LIQUID LINE
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - A/C PLUMBING) and (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - CAUTION - A/C PLUMBING).
NOTE: On models equipped with the optional rear
A/C system, the rear section of the front air condi-
tioner liquid line also includes a liquid line hose
and tube extension that connects the front liquid
line to the underbody liquid line for the rear A/C
system.
(1) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - FRONT/REFRIGERANT - STAN-
DARD PROCEDURE - REFRIGERANT
RECOVERY).
(2) Disconnect and isolate the battery negative
cable.
(3) Remove the air cleaner housing from the right
side of the engine compartment.
(4) Disconnect the drain tube from the wiper mod-
ule drain on the right side of the engine compart-
ment.
(5) Remove the A/C pressure transducer (Refer to
24 - HEATING & AIR CONDITIONING/CONTROLS
- FRONT/A/C PRESSURE TRANSDUCER -
REMOVAL).(6) If equipped, remove the nut that secures the
A/C ground strap to the weld stud on the top of the
right front strut tower (Fig. 7).
(7) If equipped, remove the A/C ground strap eye-
let terminal connector from the weld stud.
(8) Remove the bolt that secures the liquid line
rear section fitting to the top of the receiver/drier.
(9) Disconnect the liquid line fitting from the
receiver/drier outlet port.
(10) Remove the O-ring seal from the liquid line
fitting and discard.
(11) Install plugs in, or tape over the opened liquid
line fitting and the receiver/drier outlet port.
(12) Remove the nut that secures the suction line
and liquid line fittings to the expansion valve.
(13) Disconnect the suction line and liquid line fit-
tings from the expansion valve.
(14) Remove the seals from the suction line and
liquid line fittings and discard.
(15) Install plugs in, or tape over the opened suc-
tion line and liquid line fittings and both expansion
valve ports.
(16) Raise and support the vehicle.
Fig. 7 Liquid Line
1 - A/C GROUND STRAP (IF EQUIPPED)
2 - NUT (IF EQUIPPED)
3 - WELD STUD (IF EQUIPPED)
4 - A/C PRESSURE TRANSDUCER
5 - WELD STUD (2)
6 - A/C EXPANSION VALVE
7 - A/C LIQUID LINE (REAR SECTION)
8 - LIQUID LINE EXTENSION (REAR A/C ONLY)
9 - NUT (2)
10 - RECEIVER/DRIER
11 - ROUTING CLIP
12 - A/C LIQUID LINE (FRONT SECTION)
RSPLUMBING - REAR24 - 105
HEATER HOSES (Continued)
(17) Cut the tie strap located just forward of the
connections between the underbody plumbing and
the engine compartment plumbing for the rear heat-
er-A/C system (Fig. 8).
(18) Disconnect the front liquid line extension fit-
ting from the underbody liquid line fitting for the
rear air conditioner.
(19) Remove the O-ring seal from the underbody
liquid line fitting and discard.
(20) Install plugs in, or tape over the opened liquid
line fittings.
(21) Lower the vehicle.
(22) Remove the liquid line from the engine com-
partment.
INSTALLATION
(1) Position the rear section of the front liquid line
into the engine compartment.
(2) Remove the tape or plugs from the suction line
and liquid line fittings and both expansion valve
ports.
(3) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the suction line
and liquid line fittings.
(4) Reconnect the liquid line and suction line fit-
tings to the expansion valve.
(5) Install the nut that secures the suction line
and liquid line fittings to the expansion valve.
Tighten the nut to 23 N´m (17 ft. lbs.).
(6) Remove the tape or plugs from the liquid line
rear section fitting for the receiver/drier and the
receiver/drier outlet port.(7) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the liquid line fitting.
(8) Reconnect the liquid line fitting to the receiver/
drier outlet port on the top of the receiver/drier.
(9) Install the bolt that secures the liquid line fit-
ting to the receiver/drier. Tighten the bolt to 11 N´m
(97 in. lbs.).
(10) If equipped, reinstall the A/C ground strap
eyelet terminal connector onto the weld stud on the
top of the right front strut tower (if equipped).
(11) If equipped, install the nut that secures the
A/C ground strap to the weld stud. Tighten the nut
to 12 N´m (106 in. lbs.)
(12) Install the A/C pressure transducer (Refer to
24 - HEATING & AIR CONDITIONING/CONTROLS/
A/C PRESSURE TRANSDUCER - INSTALLATION).
(13) Reconnect the drain tube to the wiper module
drain on the right side of the engine compartment.
(14) Reinstall the air cleaner housing into the
right side of the engine compartment.
(15) Raise and support the vehicle.
(16) Remove the tape or plugs from the liquid line
rear section extension fitting and the underbody liq-
uid line fitting.
(17) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the underbody liquid
line fitting.
(18) Reconnect the liquid line rear section exten-
sion fitting to the underbody liquid line fitting.
Tighten the fittings to 23 N´m (17 ft. lbs.).
(19) Install a new tie strap just forward of the con-
nections between the underbody plumbing and the
engine compartment plumbing for the rear heater-
A/C system.
(20) Lower the vehicle.
(21) Reconnect the battery negative cable.
(22) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(23) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
SUCTION LINE
REMOVAL
On models equipped with the optional rear A/C
system, the front air conditioner suction line also
includes a suction line hose and tube extension that
connects the front suction line to the underbody suc-
tion line for the rear A/C system.
Fig. 8 Underbody A/C Line Front Connections ±
Typical
1 - SUCTION LINE EXTENSION TUBE
2 - LIQUID LINE EXTENSION TUBE
3 - RETAINING STRAP
4 - REAR HEATER EXTENSION TUBES
5 - UNDERBODY REFRIGERANT LINES
24 - 106 PLUMBING - REARRS
LIQUID LINE (Continued)
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
is enabled to run another test during that trip. When
the test fails three times, the counter increments to
three, a malfunction is entered, and a Freeze Frame
is stored. When the counter increments to three dur-
ing the next trip, the code is matured and the MIL is
illuminated. If the test passes the first, no further
testing is conducted during that trip.
The MIL is extinguished after three consecutive
good trips. The good trip criteria for the catalyst
monitor is more stringent than the failure criteria. In
order to pass the test and increment one good trip,
the downstream sensor switch rate must be less than
80% of the upstream rate (60% for manual transmis-
sions). The failure percentages are 90% and 70%
respectively.
Enabling ConditionsÐThe following conditions
must typically be met before the PCM runs the cat-
alyst monitor. Specific times for each parameter may
be different from engine to engine.
²Accumulated drive time
²Enable time
²Ambient air temperature
²Barometric pressure
²Catalyst warm-up counter
²Engine coolant temperature²Accumulated throttle position sensor
²Vehicle speed
²MAP
²RPM
²Engine in closed loop
²Fuel level
Pending ConditionsÐ
²Misfire DTC
²Front Oxygen Sensor Response
²Front Oxygen Sensor Heater Monitor
²Front Oxygen Sensor Electrical
²Rear Oxygen Sensor Rationality (middle check)
²Rear Oxygen Sensor Heater Monitor
²Rear Oxygen Sensor Electrical
²Fuel System Monitor
²All TPS faults
²All MAP faults
²All ECT sensor faults
²Purge flow solenoid functionality
²Purge flow solenoid electrical
²All PCM self test faults
²All CMP and CKP sensor faults
²All injector and ignition electrical faults
²Idle Air Control (IAC) motor functionality
²Vehicle Speed Sensor
²Brake switch
²Intake air temperature
ConflictÐThe catalyst monitor does not run if any
of the following are conditions are present:
²EGR Monitor in progress
²Fuel system rich intrusive test in progress
²EVAP Monitor in progress
²Time since start is less than 60 seconds
²Low fuel level
²Low ambient air temperature
²Ethanel content learn is taking place and the
ethenal used once flag is set
SuspendÐThe Task Manager does not mature a
catalyst fault if any of the following are present:
²Oxygen Sensor Monitor, Priority 1
²Upstream Oxygen Sensor Heater, Priority 1
²EGR Monitor, Priority 1
²EVAP Monitor, Priority 1
²Fuel System Monitor, Priority 2
²Misfire Monitor, Priority 2
NON-MONITORED CIRCUITS
The PCM does not monitor all circuits, systems
and conditions that could have malfunctions causing
driveability problems. However, problems with these
systems may cause the PCM to store diagnostic trou-
ble codes for other systems or components. For exam-
ple, a fuel pressure problem will not register a fault
directly, but could cause a rich/lean condition or mis-
fire. This could cause the PCM to store an oxygen
sensor or misfire diagnostic trouble code.
RSEMISSIONS CONTROL25-5
EMISSIONS CONTROL (Continued)
EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
OPERATION - EVAPORATION CONTROL
SYSTEM............................11
SPECIFICATIONS
TORQUE............................12
EVAP/PURGE SOLENOID
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................13
INSTALLATION.........................13
FUEL FILLER CAP
DESCRIPTION.........................13
OPERATION...........................13
NATURAL VAC LEAK DETECTION ASSY
REMOVAL.............................14
INSTALLATION.........................14
LEAK DETECTION PUMP
REMOVAL.............................15
INSTALLATION.........................15
ORVR
OPERATION...........................15DIAGNOSIS AND TESTING - VEHICLE DOES
NOT FILL............................17
P C V VA LV E
DESCRIPTION.........................18
OPERATION...........................18
DIAGNOSIS AND TESTING - PCV SYSTEM . . . 18
VAPOR CANISTER
DESCRIPTION.........................19
OPERATION...........................19
REMOVAL
REMOVAL...........................19
REMOVAL - WITH NVLD - FOLD-IN-FLOOR . 20
REMOVAL - REAR EVAP CANISTER.......20
INSTALLATION
INSTALLATION.......................20
INSTALLATION - WITH NVLD - FOLD-IN-
FLOOR.............................20
INSTALLATION - REAR EVAP CANISTER . . . 21
EVAPORATIVE EMISSIONS
OPERATION - EVAPORATION CONTROL
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 to an activated carbon
filled evaporative canister. The canister temporarily
holds the vapors. The Powertrain Control Module
(PCM) allows intake manifold vacuum to draw
vapors into the combustion chambers during certain
operating conditions (Fig. 1).All engines use a proportional purge solenoid sys-
tem. The PCM controls vapor flow by operating the
purge solenoid. Refer to Proportional Purge Solenoid
in this section.
NOTE: The evaporative system uses specially man-
ufactured hoses. If they need replacement, only use
fuel resistant hose. Also the hoses must be able to
pass an Ozone compliance test.
NOTE: For more information on Onboard Refueling
Vapor Recovery (ORVR), refer to the Fuel Delivery
section.
RSEVAPORATIVE EMISSIONS25-11
(2) Install hose on PCV valve. Remove the
make-up air hose from the air plenum at the rear of
the engine. Hold a piece of stiff paper (parts tag)
loosely over the end of the make-up air hose.
(3) After allowing approximately one minute for
crankcase pressure to reduce, the paper should draw
up against the hose with noticeable force. If the
engine does not draw the paper against the grommet
after installing a new valve, replace the PCV valve
hose.
(4) Turn the engine off. Remove the PCV valve
from intake manifold. The valve should rattle when
shaken.
(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.
If the valve rattles, apply a light coating of Loctitet
Pipe Sealant With Teflon to the threads. Thread the
PCV valve into the manifold plenum and tighten to 7
N´m (60 in. lbs.) torque.
VAPOR CANISTER
DESCRIPTION
There are 2 EVAP canisters on the vehicle. The
vacuum and vapor tubes connect to the top of the
canister. It is a charcoal canister (Fig. 15) or (Fig.
16).OPERATION
All vehicles use a maintenance free, evaporative
(EVAP) canister. Fuel tank vapors vent into the can-
ister. The canister temporarily holds the fuel vapors
until intake manifold vacuum draws them into the
combustion chamber. The Powertrain Control Module
(PCM) purges the canister through the proportional
purge solenoid. The PCM purges the canister at pre-
determined intervals and engine conditions.
Purge Free Cells
Purge-free memory cells are used to identify the
fuel vapor content of the evaporative canister. Since
the evaporative canister is not purged 100% of the
time, the PCM stores information about the evapora-
tive canister's vapor content in a memory cell.
The purge-free cells are constructed similar to cer-
tain purge-normal cells. The purge-free cells can be
monitored by the DRB IIItScan Tool. The only dif-
ference between the purge-free cells and normal
adaptive cells is that in purge-free, the purge is com-
pletely turned off. This gives the PCM the ability to
compare purge and purge-free operation.
REMOVAL
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the 2 hoses (Fig. 15).
(3) Remove bolt.
(4) Pull canister rearward to remove.
Fig. 15 FRONT EVAP CANISTER
1 - Front EVAP Canister
2 - Vent Valve
Fig. 16 REAR EVAP CANISTER
1 - Rear EVAP Canister
2 - Front EVAP Canister
3 - Vent Valve
RSEVAPORATIVE EMISSIONS25-19
PCV VALVE (Continued)