
WATER PUMP DIAGNOSIS
A quick flow test to tell whether or not the pump is
working is to see if the heater warms properly. A
defective pump will not be able to circulate heated
coolant through the long heater hose.
Another flow test to help determine pump opera-
tion:
WARNING: DO NOT remove radiator cap if the cool-
ing system is hot or under pressure.
(1) Remove cooling system pressure cap.
(2) Remove a small amount of coolant from the
system.
(3) Start the engine and warm up until thermostat
opens.
(4) With the thermostat open and coolant level low,
visually inspect for coolant flow. If flow is present,
the water pump is pumping coolant through the sys-
tem.
COOLING SYSTEM FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use the following procedures:
(1) If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper
radiator hose. If it is hot, coolant is circulating.
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP WITH THE SYSTEM HOT AND
UNDER PRESSURE BECAUSE SERIOUS BURNS
FROM COOLANT CAN OCCUR.
(2) Remove pressure cap when engine is cold,
remove small amount of coolant Idle engine until
thermostat opens, you should observe coolant flow
while looking down the filler neck. Once flow is
detected install the pressure cap.
ELECTRIC FAN MOTOR TEST
Refer to Powertrain Diagnostic Manual for proce-
dure.
COOLANT CONCENTRATION TESTING
Coolant concentration should be checked when any
additional coolant was added to system or after a
coolant drain, flush and refill. The coolant mixture
offers optimum engine cooling and protection against
corrosion when mixed to a freeze point of -37ÉC
(-34ÉF) to -59ÉC (-50ÉF). The use of a hydrometer or a
refractometer can be used to test coolant concentra-
tion.
A hydrometer will test the amount of glycol in a
mixture by measuring the specific gravity of the mix-
ture. The higher the concentration of ethylene glycol,
the larger the number of balls that will float, andhigher the freeze protection (up to a maximum of
70% by volume glycol).
A refractometer will test the amount of glycol in a
coolant mixture by measuring the amount a beam of
light bends as it passes through the fluid.
Some coolant manufactures use other types of gly-
cols into their coolant formulations. Propylene glycol
is the most common new coolant. However, propylene
glycol based coolants do not provide the same freez-
ing protection and corrosion protection and is only
recommended for limited usage. Refer to appropriate
Technical Service Bulletin(s) regarding use of propy-
lene glycol based coolants.
CAUTION: Do not mix types of coolantÐcorrosion
protection will be severely reduced.
Because ethylene glycol and propylene glycol do
not have the same specific gravities, the use of a
hydrometer will be inaccurate. Therefore, Special
Tool 8286 refractometer, is recommended when test-
ing either ethylene or propylene glycol coolants.
TESTING COOLING SYSTEM FOR LEAKS
The system should be full. With the engine not
running, wipe the filler neck sealing seat clean.
Attach a radiator pressure tester to the filler neck,
as shown in (Fig. 12) and apply 104 kPa (15 psi)
pressure. If the pressure drops more than 2 psi in 2
minutes, inspect the system for external leaks.
Move all hoses at the radiator and heater while
system is pressurize at 15 psi, since some leaks occur
due to engine rock while driving.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start the
engine, and run the engine to normal operating tem-
perature in order to open the thermostat and allow
Fig. 12 Pressure Testing Cooling SystemÐTypical
1 ± PRESSURE TESTER
PLCOOLING SYSTEM 7 - 15
DIAGNOSIS AND TESTING (Continued)

the coolant to expand. Reattach the tester. If the nee-
dle on the dial fluctuates it indicates a combustion
leak, usually a head gasket leak.
WARNING: WITH THE PRESSURE TESTER IN
PLACE PRESSURE BUILDS UP QUICKLY. ANY
EXCESSIVE PRESSURE BUILD-UP DUE TO CON-
TINUOUS ENGINE OPERATION MUST BE
RELEASED TO A SAFE PRESSURE POINT. NEVER
PERMIT PRESSURE TO EXCEED 138 kPa (20 psi).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam is emitted from the tail pipe, it may
indicate a faulty head gasket, cracked engine block,
or cracked cylinder head.
There may be internal leaks, which can be deter-
mined by removing the oil dipstick. If water globules
appear intermixed with the oil, it indicates an inter-
nal leak in the engine. If there is an internal leak,
the engine must be disassembled for repair.
PRESSURE CAP TO FILLER NECK SEAL
PRESSURE RELIEF CHECK
The pressure cap upper gasket (seal) pressure
relief can be checked by removing the overflow hose
at the radiator filler neck nipple (Fig. 13). Attach the
radiator pressure tester to thefiller neck nipple,
and pump air into the system. The pressure cap
upper gasket should relieve pressure at 69-124 kPa
(10-18 psi), and hold pressure at 55 kPa (8 psi) min-
imum.
WARNING: THE WARNING WORDS DO NOT OPEN
HOT ON THE PRESSURE CAP IS A SAFETY PRE-
CAUTION. WHEN HOT, THE COOLING SYSTEM
BUILDS UP PRESSURE. TO PREVENT SCALDING
OR OTHER INJURY, THE PRESSURE CAP SHOULD
NOT BE REMOVED WHILE THE SYSTEM IS HOT
AND/OR UNDER PRESSURE.
There is no need to remove the pressure cap at any
timeexceptfor the following purposes:
²Check and adjust coolant freeze point
²Refill system with new coolant
²Conducting service procedures
²Checking for leaks
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT 15 MINUTES BEFORE REMOVING CAP.
PLACE A SHOP TOWEL OVER THE CAP, AND WITH-
OUT PUSHING DOWN, ROTATE IT COUNTER-
CLOCKWISE TO THE FIRST STOP. ALLOW FLUIDSTO ESCAPE THROUGH THE OVERFLOW TUBE.
WHEN THE SYSTEM STOPS PUSHING COOLANT
AND STEAM INTO THE CRS TANK AND PRESSURE
DROPS, PUSH DOWN ON THE CAP AND REMOVE
IT COMPLETELY. SQUEEZING THE RADIATOR
INLET HOSE WITH A SHOP TOWEL (TO CHECK
PRESSURE) BEFORE AND AFTER TURNING TO
THE FIRST STOP IS RECOMMENDED.
PRESSURE TESTING COOLING SYSTEM
PRESSURE CAP
Dip the pressure cap in water; clean off any depos-
its on the vent valve or its seat, and apply the cap to
end of radiator pressure tester (Fig. 14). Working the
plunger, increase the pressure to 104 kPa (15 psi) on
the gauge. If the pressure cap fails to hold pressure
of at least 97 kPa (14 psi), replace the cap.
Fig. 13 Cooling System Pressure Cap
1 ± PRESSURE RATING
2 ± FILLER NECK SEAL
3 ± PRESSURE VALVE
4 ± VACUUM VENT VALVE (SHOWN IN SEALING POSITION)
7 - 16 COOLING SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

(3) Remove thermostat/engine outlet connector
bolts (Fig. 22).
(4) Remove thermostat and O-ring assembly.
INSTALLATION
(1) Clean all sealing surfaces.
(2) Place the new thermostat assembly into the
thermostat housing/outlet connector. Align vent with
notch in cylinder head.
(3) Install thermostat housing/outlet connector
onto cylinder head and tighten bolts to 12.5 N´m (110
in. lbs.).
(4) Install upper radiator hose.
(5) Connect the coolant recovery/reserve system
hose.
(6) Refill cooling system. Refer to procedure in this
section.
RADIATOR
REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK PLUG OR THE RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
(1) Disconnect negative cable from battery.
(2) Drain cooling system. Refer to procedure in
this section.
(3) Remove upper radiator hose from the radiator.
(4) Disconnect and cap automatic transmission
hoses, if equipped.(5) Disconnect cooling fan motor electrical connec-
tor.
(6) Remove cooling fan module retaining screws,
located on the top of the shroud (Fig. 23). Lift shroud
up and out of bottom shroud attachment clips sepa-
rating shroud from radiator.
(7) Remove the lower radiator hose.
(8) Remove upper radiator isolator bracket mount-
ing screws (Fig. 24). Disconnect the engine block
heater wire, if equipped.
(9) Remove the air conditioning condenser attach-
ing screws located at the front of the radiator, if
equipped (Fig. 25), then lean condenser forward.
NOTE: It is not necessary to discharge the air con-
ditioning system to remove the radiator.
Fig. 22 Thermostat/Engine Outlet Connector
1 ± PRESSURE CAP
2 ± THERMOSTAT HOUSING/ENGINE OUTLET CONNECTOR
3 ± THERMOSTAT
4 ± O-RING
5 ± VENT FACING UP
Fig. 23 Fan Module Mounting
1 ± SCREWS
2 ± LOWER MOUNTS
3 ± FAN MOTOR ELECTRICAL CONNECTOR
Fig. 24 Radiator Mounting
1 ± UPPER RADIATOR HOSE
2 ± UPPER RADIATOR MOUNTS
PLCOOLING SYSTEM 7 - 21
REMOVAL AND INSTALLATION (Continued)

(10) Radiator can now be lifted free from engine
compartment.Care should be taken not to dam-
age radiator cooling fins or water tubes during
removal.
INSTALLATION
(1) Slide radiator down into position behind radia-
tor support (yoke).
(2) Attach air conditioning condenser to radiator, if
equipped (Fig. 25), with four mounting screws.
Tighten screws to 5.4 N´m (50 in. lbs.). Then seat the
radiator assembly lower rubber isolators into the
mounting holes provided in the lower crossmember.
(3) Install and tighten radiator isolator mounting
bracket screws to 10 N´m (90 in. lbs.) (Fig. 24). The
radiator should have clearance to move up, approxi-
mately 5±8 mm (0.20±0.31 in.) after assembled.
(4) Install lower radiator hose. Align the hose and
position the clamp so it will not interfere with engine
components.
(5) Connect automatic transmission hoses, if
equipped. Tighten hose clamps to 2 N´m (18 in. lbs.).
(6) Slide fan module down into clip(s) on lower
radiator flange (Fig. 23). Install retaining screws and
tighten to 7.5 N´m (65 in. lbs.).
(7) Connect the cooling fan motor electrical connec-
tor.
(8) Install upper radiator hose. Align the hose and
position the clamp so they will not interfere with the
engine or the hood.
(9) Connect negative cable to battery.
(10) Fill cooling system with coolant. Refer to pro-
cedure in this section.
(11) Operate engine until it reaches normal operat-
ing temperature. Check cooling system and auto-
matic transmission for correct fluid levels.
RADIATOR DRAINCOCK
REMOVAL
(1) Turn the drain cock stem counterclockwise to
unscrew the stem. When the stem is unscrewed to
the end of the threads, pull the stem (Fig. 26) from
the radiator tank.
INSTALLATION
(1) Push the draincock assembly body into the
tank opening.
(2) Tighten the draincock stem by turning clock-
wise to 2.0-2.7 N´m (18-25 in. lbs.).
COOLING FAN MODULE
All models use a single speed electric motor driven
cooling system fan. The fan module includes a motor,
fan blade, and support shroud. The module is fas-
tened to the radiator by screws.
REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK PLUG OR THE RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
(1) Disconnect negative cable from battery.
(2) Drain cooling system below upper radiator hose
level. Refer to procedure in this section.
(3) Remove upper radiator hose from radiator (Fig.
27).
(4) Disconnect fan module electrical connector.
(5) Remove fan module screws from radiator (Fig.
28).
(6) Lift fan shroud up and out of lower shroud
attachment clips.
(7) Refer to Disassembly and Assembly in this sec-
tion for fan module sub-component service proce-
dures.
Fig. 25 A/C Condenser to Radiator Mounting Screws
1 ± AIR CONDITIONING CONDENSER TO RADIATOR
MOUNTING SCREWS
2 ± LOWER ISOLATOR MOUNTS
Fig. 26 Draincock
1 ± DRAIN COCK BODY
2 ± DRAIN COCK HOUSING
7 - 22 COOLING SYSTEMPL
REMOVAL AND INSTALLATION (Continued)

DESCRIPTION AND OPERATION
BATTERY IGNITION OFF DRAW (IOD)
A completely normal vehicle will have a small
amount of current drain on the battery with the key
out of the ignition. It can range from 4 to 10 milli-
amperes after all the modules time out. If a vehicle
will not be operated for approximately a 20 days, the
IOD fuse should be disconnected to minimize the
vehicle electrical drain on the battery. The IOD fuse
is located in the Power Distribution Center (PDC).
Refer to the PDC cover to locate the proper fuse.
CHARGING TIME REQUIRED
WARNING: NEVER EXCEED 20 AMPS WHEN
CHARGING A COLD -1ÉC (30ÉF) BATTERY. PER-
SONAL INJURY MAY RESULT.
The time required to charge a battery will vary
depending upon the following factors.
SIZE OF BATTERY
A completely discharged large heavy-duty battery
may require more recharging time than a completely
discharged small capacity battery, refer to Battery
Charging Timetable for charging times.
TEMPERATURE
A longer time will be needed to charge a battery at
-18ÉC (0ÉF) than at 27ÉC (80ÉF). When a fast charger
is connected to a cold battery, current accepted by
battery will be very low at first. In time, the battery
will accept a higher rate as battery temperature
warms.
CHARGER CAPACITY
A charger which can supply only five amperes will
require a much longer period of charging than a
charger that can supply 20 amperes or more.
STATE OF CHARGE
A completely discharged battery requires more
charging time than a partially charged battery.
NOTE: Do not attempt to recharge a battery with a
yellow/clear test indicator.
Electrolyte is nearly pure water in a completely
discharged battery. At first, the charging current
amperage will be low. As water is converted back to
sulfuric acid inside the battery, the current amp rate
will rise. Also, the specific gravity of the electrolyte
will rise, bringing the green ball (Fig. 2) into view at
approximately 75 percent state-of-charge.
BATTERY CHARGING TIMETABLE
CHARGING
AMPERAGE5
AMPERES10
AMPERES20
AMPERES
OPEN
CIRCUIT
VOLTAGEHOURS CHARGING AT 21É C (70É F)
12.25 TO
12.496 HOURS 3 HOURS 1.5 HOURS
12.00 TO
12.2410 HOURS 5 HOURS 2.5 HOURS
10.00 TO
11.9914 HOURS 7 HOURS 3.5 HOURS
*BELOW
10.0018 HOURS 9 HOURS 4.5 HOURS
*REFER TO CHARGING A COMPLETELY DISCHARGED
BATTERY
Fig. 2 Reading Test Indicator
1 ± TEST INDICATOR/STATE OF CHARGE
2 ± REPLACE BATTERY
3 ± CLEAR
4 ± BLACK
5 ± GREEN
8A - 2 BATTERYPL

DIAGNOSIS AND TESTING
BATTERY BUILT-IN TEST INDICATOR
USING TEST INDICATOR
The Test Indicator (Fig. 2), (Fig. 3) and (Fig. 4)
measures the specific gravity of the electrolyte. Spe-
cific Gravity (SG) of the electrolyte will show state-
of-charge (voltage). The test indicator WILL NOT
show cranking capacity of the battery. Refer to Bat-
tery Load Test for more information. Look into the
sight glass (Fig. 2), (Fig. 4) and note the color of the
indicator. Refer to the following description of colors:
NOTE: GREEN = 75 to 100% state-of-charge
The battery is adequately charged for further test-
ing and may be returned to use. If the vehicle will
not crank for a maximum 15 seconds, refer to BAT-
TERY LOAD TEST in this Group for more informa-
tion.
NOTE: BLACK OR DARK=0to75%state-of-chargeThe battery is INADEQUATELY charged and must
be charged until green dot is visible, (12.4 open cir-
cuit volts or greater) before the battery is tested or
returned to use. Refer to Causes of Battery Discharg-
ing in this group for more information.
NOTE: CLEAR COLOR = Replace Battery
WARNING: DO NOT CHARGE, ASSIST BOOST,
LOAD TEST, OR ADD WATER TO THE BATTERY
WHEN CLEAR COLOR DOT IS VISIBLE. PERSONAL
INJURY MAY OCCUR.
A clear color dot shows electrolyte level in battery
is below the test indicator (Fig. 2). Water cannot be
added to a maintenance free battery. The battery
must be replaced. A low electrolyte level may be
caused by an over charging condition. Refer to Gen-
erator Test Procedures on Vehicle.
CAUSES OF BATTERY DISCHARGING
It is normal to have a small 5 to 25 milliamperes
continuous electrical draw from the battery. This
draw will take place with the ignition in the OFF
position, and the courtesy, dome, storage compart-
ments, and engine compartment lights OFF. The con-
tinuous draw is due to various electronic features or
accessories that require electrical current with the
ignition OFF to function properly. When a vehicle is
not used over an extended period of approximately 20
days the IOD fuse should be pulled. The fuse is
located in the power distribution center. Disconnec-
tion of this fuse will reduce the level of battery dis-
charge. Refer to the Battery Diagnosis and Testing
table, and to the proper procedures.
Fig. 3 Battery Construction and Test Indicator -
Typical
1 ± POSITIVE POST
2 ± VENT
3 ± TEST INDICATOR
4 ± VENT
5 ± NEGATIVE POST
6 ± PLATE GROUPS
7 ± ELECTROLYTE LEVEL
8 ± GREEN BALL
9 ± MAINTENANCE FREE BATTERY
Fig. 4 Test Indicator - Typical
1 ± SIGHT GLASS
2 ± PLASTIC TUBE
3 ± GREEN BALL
4 ± BATTERY TOP
PLBATTERY 8A - 3

Refer to Group 8W, Wiring Diagrams. If OK go to
Step 7.
(7) Install interior lamp fuse. After installing fuse,
the current can reach 250 milliamperes. After time-
out the reading should not exceed 8 milliamperes. If
NOT OK go to Step 8. If OK go to Step 9.
²Ignition key lamp system
²Radio
²Remote keyless entry module, if equipped
(8) Disconnect radio and ignition switch key lamp
one component at time, to see if any component is at
fault. If the high reading is not eliminated there is a
short circuit in the wiring. Refer to Group 8W, Wir-
ing Diagrams.
CAUTION: Always disconnect the meter before
opening a door.
(9) Remove interior lamps fuse and install the fuel
pump fuse. The reading should be between 1-3 milli-
amperes. If reading is higher than 3 milliamperes:
(a) Disconnect Powertrain Control Module.
(b) If reading drops to zero, replace Powertrain
Control Module.
(c) If reading remains the same there is a cur-
rent draw or short circuit in the A14 circuit. Refer
to Group 8W, Wiring Diagrams.
BATTERY LOAD TEST
A fully charged battery must have cranking capac-
ity, to provide the starter motor and ignition system
enough power to start the engine over a broad range
of ambient temperatures. A battery load test will ver-
ify the actual cranking capability of the battery.WARNING: IF BATTERY SHOWS SIGNS OF FREEZ-
ING, LEAKING, LOOSE POSTS, OR EXCESSIVELY
LOW ELECTROLYTE LEVEL, DO NOT TEST. ACID
BURNS OR AN EXPLOSIVE CONDITION MAY
RESULT.
(1) Remove both battery cables, negative cable
first. The battery top, cables and posts should be
clean. If green dot is not visible in indicator, charge
the battery. Refer to Battery Charging Procedures in
this group.
(2) Connect a Volt/Ammeter/Load tester to the bat-
tery posts (Fig. 8). Rotate the load control knob of the
Carbon pile rheostat to apply a 300 amp load. Apply
this load for 15 seconds to remove the surface charge
from the battery, and return the control knob to off
(Fig. 9).
(3) Allow the battery to stabilize for 2 minutes,
and then verify open circuit voltage.
Fig. 7 Milliampere Meter Connection
1 ± NEGATIVE TERMINAL
2 ± MILLIAMPERE METER
3 ± PDC
4 ± AIR CLEANER HOUSING
5 ± NEGATIVE BATTERY POST
Fig. 8 Volt-Ammeter Load Tester Connections -
Typical
1 ± INDUCTION AMPMETER CLAMP
2 ± NEGATIVE CLAMP
3 ± POSITIVE CLAMP
Fig. 9 Remove Surface Charge From Battery
8A - 6 BATTERYPL
DIAGNOSIS AND TESTING (Continued)

²It passes the 15 second load test. Refer to Bat-
tery Load Test.
²The built in test indicator dot is GREEN (Fig.
2).
NOTE: The battery cannot be refilled with water, it
must be replaced.
WARNING: DO NOT CHARGE A BATTERY THAT
HAS EXCESSIVELY LOW ELECTROLYTE LEVEL.
BATTERY MAY SPARK INTERNALLY AND
EXPLODE. EXPLOSIVE GASES FORM OVER THE
BATTERY. DO NOT SMOKE, USE FLAME, OR CRE-
ATE SPARKS NEAR BATTERY. DO NOT ASSIST
BOOST OR CHARGE A FROZEN BATTERY. BAT-
TERY CASING MAY FRACTURE. BATTERY ACID IS
POISON, AND MAY CAUSE SEVERE BURNS. BAT-
TERIES CONTAIN SULFURIC ACID. AVOID CON-
TACT WITH SKIN, EYES, OR CLOTHING. IN THE
EVENT OF CONTACT, FLUSH WITH WATER AND
CALL PHYSICIAN IMMEDIATELY. KEEP OUT OF
REACH OF CHILDREN.
CAUTION: Disconnect the battery NEGATIVE cable
first, before charging battery to avoid damage to
electrical systems. Lift the red battery boot cover
from the positive cable clamp. Do not exceed 16.0
volts while charging battery. Refer to the instruc-
tions supplied with charging equipment
Battery electrolyte may bubble inside of battery
case while being charged properly. If the electrolyte
boils violently, or is discharged from the vent holes
while charging, immediately reduce charging rate or
turn off charger. Evaluate battery condition. Battery
damage may occur if charging is excessive.
Some battery chargers are equipped with polarity
sensing devices to protect the charger or battery from
being damaged if improperly connected. If the bat-
tery state of charge is too low for the polarity sensor
to detect, the sensor must be bypassed for charger to
operate. Refer to operating instructions provided
with battery charger being used.
CAUTION: Charge battery until test indicator
appears green. Do not overcharge.
It may be necessary to jiggle the battery or vehicle
to bring the green dot in the test indicator into view.
After the battery has been charged to 12.4 volts or
greater, perform a load test to determine cranking
capacity. Refer to Battery Load Test in this Group. If
the battery passes the load test, the battery is OK to
use. If battery will not pass the load test, it must be
replaced. Properly clean and inspect battery holddowns, tray, terminals, cables, posts, and top before
completing service.
CHARGING COMPLETELY DISCHARGED
BATTERY
The following procedure should be used to recharge
a completely discharged battery. Unless procedure is
properly followed, a good battery may be needlessly
replaced. Refer to Battery Charging Rate Table for
proper charging time.
(1) Measure the voltage at battery posts with a
voltmeter accurate to 1/10 volt (Fig. 12). If below 10
volts, charge current will be low, and it could take
some time before it accepts a current in excess of a
few milliamperes. Such low current may not be
detectable on amp meters built into many chargers.
(2) Connect charger leads. Some chargers feature
polarity protection circuitry that prevents operation
unless charger is connected to battery posts correctly.
A completely discharged battery may not have
enough voltage to activate this circuitry. This may
happen even though the leads are connected properly.
(3) Battery chargers vary in the amount of voltage
and current they provide. For the time required for
the battery to accept measurable charger current at
various voltages, refer to the Battery Charging Rate
table. If charge current is still not measurable after
charging times, the battery should be replaced. If
charge current is measurable during charging time,
the battery may be good, and charging should be
completed in the normal manner.
BATTERY CHARGING RATE
Voltage Hours
16.0 volts maximum up to 4 hours
14.0 to 15.9 volts up to 8 hours
13.9 volts or less up to 16 hours
Fig. 12 Voltmeter Accurate to 1/10 Volt (Connected)
8A - 8 BATTERYPL
SERVICE PROCEDURES (Continued)