2002 JEEP GRAND CHEROKEE Calibrate tire

data bus messages are being received for initial oper-
ation. Initiate the self-diagnostic test as follows:
(1) With the ignition switch in the Off position,
simultaneously depress and hold the C/T button and
the Reset button.
(2) Turn the ignition switch to the On position.
(3) Continue to hold both buttons depressed until
the EVIC software version information is displayed,
then release both buttons.
(4) Following completion of these tests, the EVIC
module will display one of the following messages:
a.Pass Self Test- Momentarily depress and
release the Reset button to return to the compass/
temperature/trip computer display mode. The EVIC
module is working properly.
b.Failed Self Test- The EVIC module has an
internal failure. The EVIC module is faulty and must
be replaced.
c.Not Receiving J1850 Message- The EVIC
module is not receiving proper message input
through the PCI data bus. This can result from one
or more faulty electronic modules in the vehicle, or
from a faulty PCI data bus. The use of a DRB scan
tool and the proper Diagnostic Procedures manual
are required for further diagnosis.
NOTE: If the compass functions, but accuracy is
suspect, it may be necessary to perform a variation
adjustment. This procedure allows the compass
unit to accommodate variations in the earth's mag-
netic field strength, based on geographic location.
Refer to Compass Variation Adjustment in the Stan-
dard Procedures section of this group.
NOTE: If the compass reading displays a blank, and
only ªCALº appears in the display, demagnetizing
may be necessary to remove excessive residual
magnetic fields from the vehicle. Refer to Compass
Demagnetizing in the Standard Procedures section
of this group.
STANDARD PROCEDURE - TIRE PRESSURE
SYSTEM TEST
The following test can be used to verify two func-
tions. One, that the tire pressure sensors are trans-
mitting properly and two, the EVIC module is
receiving these transmissions accordingly.
(1) Retrain the tire sensors (Refer to 22 - TIRES/
WHEELS/TIRE PRESSURE MONITORING/SEN-
SOR - STANDARD PROCEDURE). The tire sensors
must be retrained in order to set the proper trans-
mitting time cycle (twice a minute), failure to retrain
the sensors will cause a much slower transmitting
time cycle (once a hour).(2) Using the STEP button on the overhead con-
sole, scroll to the blank display, then press the
RESET button for five seconds, a beep will sound
indicating the start of this test. The vehicle icon and
transmission counters will now be displayed, (same
display as individual tire pressure except counters
replace tire pressure values).
(3) Upon entering the test mode, the EVIC will
clear the sensor counter and each time a sensor sig-
nal for a road tire is received, the EVIC will update
the counter value (vehicle must be driven at 25 mph
to transmit). The counter values should all read the
same value. If any of the road tires indicate a differ-
ent value than another tire sensor, this is a sign of a
problem. Replace the appropriate tire sensor and
retest the system. This test will continue until any of
the overhead console buttons are pressed or the igni-
tion is turned off.
NOTE: Pressing the RESET button during the test
will sound a beep and reset all the counter values
back to zero.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the overhead console from the head-
liner (Refer to 8 - ELECTRICAL/OVERHEAD CON-
SOLE - REMOVAL).
(3) Remove the four screws that secure the Elec-
tronic Vehicle Information Center (EVIC) module to
the overhead console housing (Fig. 5).
(4) Remove the EVIC module from the overhead
console housing.
INSTALLATION
(1) Position the EVIC module onto the overhead
console housing.
(2) Install and tighten the four screws that secure
the EVIC module to the overhead console housing.
Tighten the screws to 0.9 N´m (8 in. lbs.).
(3) Install the overhead console onto the headliner
(Refer to 8 - ELECTRICAL/OVERHEAD CONSOLE -
INSTALLATION).
(4) Reconnect the battery negative cable.
NOTE: If a new EVIC module has been installed, the
compass will have to be calibrated and the variance
set. Refer to Compass Variation Adjustment and
Compass Calibration in the Service Procedures sec-
tion of this group for the procedures.
8M - 10 MESSAGE SYSTEMSWJ
ELECTRONIC VEHICLE INFO CENTER (Continued)

ING & AIR CONDITIONING/CONTROLS/A/C
PRESSURE TRANSDUCER - INSTALLATION).
(9) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(10) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(11) Connect the negative battery cable.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Remove the tape or plugs from the discharge
line block fitting and the manifold on the compressor.
Install the discharge line block fitting to the manifold
on the compressor. Tighten the mounting bolt to 25.4
N´m (225 in. lbs.).
(2) Remove the tape or plugs from the refrigerant
line fittings on the condenser inlet and the discharge
line. Connect the discharge line to the condenser
inlet. Tighten the retaining nut to 28 N´m (250 in.
lbs.).
(3) Install the a/c high pressure transducer(Refer
to 24 - HEATING & AIR CONDITIONING/CON-
TROLS/A/C PRESSURE TRANSDUCER - INSTAL-
LATION).
(4) Connect the battery negative cable.
(5) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)(6) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
A/C EXPANSION VALVE
DESCRIPTION
The ªHº valve type thermal expansion valve (TXV)
is located at the front of the heater-A/C housing
between the liquid and suction lines and the evapo-
rator coil.
The expansion valve is a factory calibrated unit
and cannot be adjusted or repaired. If faulty or dam-
aged, the expansion valve must be replaced.
OPERATION
High-pressure, high temperature liquid refrigerant
from the liquid line passes through the expansion
valve orifice, converting it inot a low-pressure, low-
temperature mixture of liquid and gas before it
enters the evaporator coil. A temperature sensor in
the expansion valve control head monitors the tem-
perature of the refrigerant leaving the evaporator coil
throught the suction line, and adjusts the orifice size
at the liquid line to let the proper amoount of refrig-
erant into the evaporator coil to meet the vehicle
cooling requirements. Controlling the refrigerant flow
through the evaporator ensures that none of the
refrigerant leaving the evaporator is still in a liquid
state, which could damage the compressor.
DIAGNOSIS AND TESTING - A/C EXPANSION
VALVE
The expansion valve is located on the engine side
of the dash panel near the shock tower.
The expansion valve can fail in three different
positions (open, closed or restricted).
In an Open Position: this will result in a noisy
compressor or no cooling. The cause can be broken
spring, broken ball or excessive moisture in the A/C
system. If the spring or ball are found to be defective,
replace the expansion valve. If excessive moisture is
found in the A/C system, recycle the refrigerant.
In a Closed Position: There will be low suction
pressure and no cooling. This may be caused by a
failed power dome or excessive moisture in the A/C
system. If the power dome on the expansion valve is
found to be defective replace the expansion valve. If
excessive moisture is found recycle the refrigerant.
A Restricted Orifice: There will be low suction
pressure and no cooling. This may be caused by
debris in the refrigerant system. If debris is believed
to be the cause, recycle the refrigerant and replace
the expansion valve and the receiver/drier.
WJPLUMBING 24 - 65
A/C DISCHARGE LINE (Continued)