2003 JEEP GRAND CHEROKEE duty cycle purge

ENGINE OIL PRESSURE SENSOR (GAS) - BLACK 3 WAY
CAV CIRCUIT FUNCTION
1 K6 18VT/BK 5 VOLT SUPPLY
2 G60 18GY/YL ENGINE OIL PRESSURE SENSOR SIGNAL
3 K4 18BK/LB SENSOR GROUND
EVAP/PURGE SOLENOID (GAS) - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 F12 20DB/WT FUSED IGNITION SWITCH OUTPUT (RUN-START)
2 K52 18PK/BK (RHD) DUTY CYCLE EVAP/PURGE SOLENOID CONTROL
2 K52 20PK/BK (LHD) DUTY CYCLE EVAP/PURGE SOLENOID CONTROL
FRONT POWER OUTLET - RED 3 WAY
CAV CIRCUIT FUNCTION
1 F85 16VT (RHD) FUSED B(+)
1 F85 16VT/WT (LHD) FUSED B(+)
2- -
3 Z300 16BK GROUND
FRONT WASHER PUMP - WHITE 2 WAY
CAV CIRCUIT FUNCTION
1 V10 20BR WASHER PUMP SWITCH SENSE
2 Z141 20BK GROUND
FRONT WIPER MOTOR - BLACK 6 WAY
CAV CIRCUIT FUNCTION
1 V6 16DB FUSED IGNITION SWITCH OUTPUT (RUN-ACC)
2 V55 16TN/RD WIPER PARK SWITCH SENSE
3- -
4 Z141 16BK GROUND
5 V3 16BR/WT WIPER HIGH/LOW RELAY LOW SPEED OUTPUT
6 V4 16RD/YL WIPER HIGH/LOW RELAY HIGH SPEED OUTPUT
8W - 80 - 78 8W-80 CONNECTOR PIN-OUTWJ

POWERTRAIN CONTROL MODULE C3 (GAS) - GRAY 32 WAY
CAV CIRCUIT FUNCTION
1 C13 18DB/OR A/C COMPRESSOR CLUTCH RELAY CONTROL
2- -
3 K51 18DB/YL AUTO SHUT DOWN RELAY CONTROL
4 V36 18TN/RD SPEED CONTROL VACUUM SOLENOID CONTROL
5 V35 18LG/RD SPEED CONTROL VENT SOLENOID CONTROL
6- -
7 K42 18DB/LG (4.7L HIGH OUTPUT) KNOCK SENSOR NO. 1 SIGNAL
8 K99 18BR/OR OXYGEN SENSOR 1/1 HEATER CONTROL
9 K512 18RD/YL (EXCEPT 4.0L
BUILT-UP-EXPORT)OXYGEN SENSOR DOWNSTREAM RELAY CONTROL
10 K106 18WT/DG (EXCEPT
BUILT-UP-EXPORT)LEAK DETECTION PUMP SOLENOID CONTROL
11 V32 18OR/DG SPEED CONTROL SUPPLY
12 F42 18DG/LG FUSED AUTO SHUT DOWN RELAY OUTPUT
13 T10 18YL/DG (4.7L RHD) TORQUE MANAGEMENT REQUEST SENSE
13 T6 18OR/WT (4.0L LHD) OVERDRIVE OFF SWITCH SENSE
13 T10 18DG/LG (4.7L LHD) TORQUE MANAGEMENT REQUEST SENSE
13 T6 18OR/BK (4.0L RHD) OVERDRIVE OFF SWITCH SENSE
14 K107 18OR/PK (EXCEPT
BUILT-UP-EXPORT)LEAK DETECTION PUMP SWITCH SENSE
15 K25 18VT/LG BATTERY TEMPERATURE SENSOR SIGNAL
16 K299 18BR/WT OXYGEN SENSOR 1/2 HEATER CONTROL
17 - -
18 K142 18GY/BK (4.7L HIGH OUTPUT) KNOCK SENSOR NO. 2 SIGNAL
19 K31 18BR FUEL PUMP RELAY CONTROL
20 K52 18PK/BK DUTY CYCLE EVAP/PURGE SOLENOID CONTROL
21 - -
22 - -
23 - -
24 K29 18WT/PK SECONDARY BRAKE SWITCH SIGNAL
25 K125 18WT/DB GENERATOR SOURCE
26 K226 18LB/YL FUEL LEVEL SENSOR SIGNAL
27 D21 18PK SCI TRANSMIT
28 - -
29 D32 18LG (LHD) SCI RECEIVE
29 D32 18LG/DG (RHD) SCI RECEIVE
30 D25 18VT/YL PCI BUS
31 - -
32 V37 18RD/LG SPEED CONTROL SWITCH SIGNAL
RADIATOR FAN MOTOR - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 C23 12DG RADIATOR FAN RELAY OUTPUT
2 Z4 12BK/PK GROUND
8W - 80 - 110 8W-80 CONNECTOR PIN-OUTWJ

EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
DESCRIPTION
DESCRIPTION - EVAPORATION CONTROL
SYSTEM............................24
DESCRIPTION - CCV SYSTEM...........25
DESCRIPTION - PCV SYSTEM...........25
OPERATION
OPERATION - 4.0L CCV SYSTEM.........26
OPERATION - 4.7L PCV SYSTEM.........26
SPECIFICATIONS
TORQUE - EVAPORATION SYSTEM.......27
CCV HOSE
DIAGNOSIS AND TESTING - CCV SYSTEM -
4.0L................................28
REMOVAL - FIXED ORIFICE FITTING........28
INSTALLATION - FIXED ORIFICE FITTING....29
EVAP/PURGE SOLENOID
DESCRIPTION.........................29
OPERATION...........................29
REMOVAL.............................29
INSTALLATION.........................29
FUEL FILLER CAP
DESCRIPTION.........................29
OPERATION...........................29REMOVAL.............................29
LEAK DETECTION PUMP
DESCRIPTION.........................30
OPERATION...........................31
DIAGNOSIS AND TESTING - ENABLING
CONDITIONS TO RUN EVAP LEAK
DETECTION TEST.....................32
REMOVAL.............................35
INSTALLATION.........................35
ORVR
DESCRIPTION.........................37
OPERATION...........................37
P C V VA LV E
DIAGNOSIS AND TESTING - PCV VALVE/PCV
SYSTEM - 4.7L.......................37
REMOVAL - PCV VALVE - 4.7L.............39
INSTALLATION - PCV VALVE - 4.7L.........39
VACUUM LINES
DESCRIPTION.........................39
VAPOR CANISTER
DESCRIPTION.........................39
OPERATION...........................39
REMOVAL.............................40
INSTALLATION.........................40
EVAPORATIVE EMISSIONS
DESCRIPTION
DESCRIPTION - 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 the control valve, through the fuel manage-
ment valve, and through vent hoses and tubes to a
charcoal filled evaporative canister. The canister tem-
porarily holds the vapors. The Powertrain Control
Module (PCM) allows intake manifold vacuum todraw vapors into the combustion chambers during
certain operating conditions.
Gas powered engines use a duty cycle purge sys-
tem. The PCM controls vapor flow by operating the
duty cycle EVAP purge solenoid. Refer to Duty Cycle
EVAP Canister Purge Solenoid.
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system for OBD II requirements.
Also refer to Leak Detection Pump.
Vehicles powered with gasoline engines are also
equipped with ORVR (On-Board Refueling Vapor
Recovery). Refer to ORVR for additional information.
25 - 24 EVAPORATIVE EMISSIONSWJ

INSTALLATION - FIXED ORIFICE FITTING
When installing fixed orifice fitting, be sure loca-
tions of fixed orifice fitting and air inlet fitting (Fig.
9) have not been inadvertently exchanged. The fixed
orifice fitting is light grey in color and is located at
rearof valve cover. The air inlet fitting is black in
color and is located atfrontof valve cover.
(1) Connect fitting to CCV breather tube.
(2) Return fixed orifice fitting to valve cover grom-
met.
EVAP/PURGE SOLENOID
DESCRIPTION
The duty cycle EVAP canister purge solenoid (DCP)
regulates the rate of vapor flow from the EVAP can-
ister to the intake manifold. The Powertrain Control
Module (PCM) operates the solenoid.
OPERATION
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 cycles
(energizes and de-energizes) the solenoid 5 or 10
times per second, depending upon operating condi-
tions. The PCM varies the vapor flow rate by chang-
ing solenoid pulse width. Pulse width is the amount
of time that the solenoid is energized. The PCM
adjusts solenoid pulse width based on engine operat-
ing condition.
REMOVAL
The duty cycle evaporative (EVAP) canister purge
solenoid is located in the engine compartment near
the brake master cylinder (Fig. 10).
(1) Disconnect electrical connector at solenoid.
(2) Disconnect vacuum lines at solenoid.
(3) Lift solenoid slot (Fig. 10) from mounting
bracket for removal.
INSTALLATION
(1) Position solenoid slot to mounting bracket.
(2) Connect vacuum lines to solenoid. Be sure vac-
uum lines are firmly connected and not leaking or
damaged. If leaking, a Diagnostic Trouble Code
(DTC) may be set with certain emission packages.
(3) Connect electrical connector to solenoid.
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 California emissions package and a
Leak Detection Pump (LDP), the cap must be tight-
ened securely. If cap is left loose, a Diagnostic
Trouble Code (DTC) may be set.
REMOVAL
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.
Fig. 10 EVAP/PURGE SOLENOID LOCATION
1 - BRAKE MASTER CYLINDER
2 - EVAP SOLENOID
3 - SLOT
4 - ELEC. CONNEC.
5 - VACUUM LINE CONNEC.
6 - TEST PORT
WJEVAPORATIVE EMISSIONS 25 - 29
CCV HOSE (Continued)

REMOVAL - PCV VALVE - 4.7L
The PCV valve is located on the oil filler tube (Fig.
23). Two locating tabs are located on the side of the
valve (Fig. 23). These 2 tabs fit into a cam lock in the
oil filler tube. An o-ring seals the valve to the filler
tube.
(1) Disconnect PCV line/hose (Fig. 23) by discon-
necting rubber hose at PCV valve fitting.
(2) Remove PCV valve at oil filler tube by rotating
PCV valve downward (counter-clockwise) until locat-
ing tabs have been freed at cam lock (Fig. 23). After
tabs have cleared, pull valve straight out from filler
tube.To prevent damage to PCV valve locating
tabs, valve must be pointed downward for
removal. Do not force valve from oil filler tube.
(3) After valve is removed, check condition of valve
o-ring (Fig. 23).
INSTALLATION - PCV VALVE - 4.7L
The PCV valve is located on the oil filler tube (Fig.
23). Two locating tabs are located on the side of the
valve (Fig. 23). These 2 tabs fit into a cam lock in the
oil filler tube. An o-ring seals the valve to the filler
tube.
(1) Return PCV valve back to oil filler tube by
placing valve locating tabs (Fig. 23) into cam lock.
Press PCV valve in and rotate valve upward. A slight
click will be felt when tabs have engaged cam lock.
Valve should be pointed towards rear of vehicle.
(2) Connect PCV line/hose and rubber hose to PCV
valve.
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
A maintenance free, EVAP canister is used on all
gasoline powered models. The canister is attached to
a two-piece support bracket located behind the left-
rear wheel.
OPERATION
The EVAP canister is filled with granules of an
activated carbon mixture. Fuel vapors entering the
EVAP canister are absorbed by the charcoal granules.
The canister serves two functions: as a temporary
fuel vapor storage point while refueling the vehicle
for the ORVR system, as a temporary vapor storage
point while the engine is running.
Fuel tank pressure vents into the EVAP canister.
Fuel vapors are temporarily held in the canister until
they can be drawn into the intake manifold. The duty
cycle EVAP canister purge solenoid allows the EVAP
canister to be purged at predetermined times and at
certain engine operating conditions.
Refer to ORVR for additional information.
Fig. 23 PCV Valve/Oil Filler Tube Location
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
WJEVAPORATIVE EMISSIONS 25 - 39
PCV VALVE (Continued)