coolant level DODGE RAM 2003 Service Repair Manual

must alwaysbe a minimum of 44 percent, year-
round in all climates. If percentage is lower, engine
parts may be eroded by cavitation. Maximum protec-
tion against freezing is provided with a 68 percent
antifreeze concentration, which prevents freezing
down to -67.7ÉC (-90ÉF). A higher percentage will
freeze at a warmer temperature. Also, a higher per-
centage of antifreeze can cause the engine to over-
heat because specific heat of antifreeze is lower than
that of water.
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
COOLANT SELECTION AND ADDITIVES
NOTE: Refer to the vehicle's coolant bottle to iden-
tify HOAT or Non-HOAT coolant. Non-HOAT coolant
is green in color.
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (glycol base coolant with
corrosion inhibitors called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain to obtain a
freeze point of -37ÉC (-35ÉF). If it loses color or
becomes contaminated, drain, flush, and replace with
fresh properly mixed coolant solution.
CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.
DESCRIPTION - TRANSFER CASE - NV241
GENII
Recommended lubricant for the NV241 GENII
transfer case is MopartATF +4, Automatic Trans-
mission Fluid.
DESCRIPTION - TRANSFER CASE - NV271
Recommended lubricant for the NV271 transfer
case is MopartATF +4, Automatic Transmission
Fluid.
DESCRIPTION - TRANSFER CASE - NV243
Recommended lubricant for the NV243 transfer case
is MopartATF +4, Automatic Transmission Fluid.
DESCRIPTION - TRANSFER CASE - NV273
Recommended lubricant for the NV273 transfer case
is MopartATF +4, Automatic Transmission Fluid.
DESCRIPTION - AXLE
NOTE: DaimlerChrysler recommends using MoparT
lubricants or lubricants of equal quality.
FRONT AXLE
²C205F - MopartGear Lubricant 75W-90
²9 1/4 AA - MopartSynthetic Gear Lubricant
75W-90
REAR AXLE
²9 1/4 - MopartSynthetic Gear Lubricant 75W-140
²10 1/2 AA - MopartSynthetic Gear Lubricant
75W-90
²11 1/2 AA - MopartSynthetic Gear Lubricant
75W-90
NOTE: Trac-LokTdifferentials require Limited Slip
Additive in the lubricant. Trac-RiteŸ differentials
DO NOT require Limited Slip Additive.
DESCRIPTION - MANUAL TRANSMISSION
NOTE: DaimlerChrysler recommends using MoparT
lubricants or lubricants of equal quality.
²
NV3500 - MopartManual Transmission Lubricant
²NV4500 - MopartSynthetic 75W85 Manual
Transmission Lubricant
²NV5600 - MopartManual Transmission Lubri-
cant
DESCRIPTION - AUTOMATIC TRANSMISSION
FLUID
NOTE: Refer to Service Procedures in this group for
fluid level checking procedures.
MopartATF +4, Automatic Transmission Fluid is
the recommended fluid for DaimlerChrysler auto-
matic transmissions.
Dexron II fluid IS NOT recommended. Clutch
chatter can result from the use of improper
fluid.
MopartATF +4, Automatic Transmission Fluid
when new is red in color. The ATF is dyed red so it
can be identified from other fluids used in the vehicle
such as engine oil or antifreeze. The red color is not
permanent and is not an indicator of fluid condition.
As the vehicle is driven, the ATF will begin to look
darker in color and may eventually become brown.
This is normal.ATF+4 also has a unique odor that
may change with age. Consequently, odor and color
cannot be used to indicate the fluid condition or the
need for a fluid change.
0 - 4 LUBRICATION & MAINTENANCEDR
FLUID TYPES (Continued)

FLUID ADDITIVES
DaimlerChrysler strongly recommends against the
addition of any fluids to the transmission, other than
those automatic transmission fluids listed above.
Exceptions to this policy are the use of special dyes
to aid in detecting fluid leaks.
Various ªspecialº additives and supplements exist
that claim to improve shift feel and/or quality. These
additives and others also claim to improve converter
clutch operation and inhibit overheating, oxidation,
varnish, and sludge. These claims have not been sup-
ported to the satisfaction of DaimlerChrysler and
these additivesmust not be used.The use of trans-
mission ªsealersº should also be avoided, since they
may adversely affect the integrity of transmission
seals.
OPERATION - AUTOMATIC TRANSMISSION
FLUID
The automatic transmission fluid is selected based
upon several qualities. The fluid must provide a high
level of protection for the internal components by
providing a lubricating film between adjacent metal
components. The fluid must also be thermally stable
so that it can maintain a consistent viscosity through
a large temperature range. If the viscosity stays con-
stant through the temperature range of operation,
transmission operation and shift feel will remain con-
sistent. Transmission fluid must also be a good con-
ductor of heat. The fluid must absorb heat from the
internal transmission components and transfer that
heat to the transmission case.
FLUID CAPACITIES
SPECIFICATIONS
FLUID CAPACITIES
2DESCRIPTIONSPECIFICATION
FUEL TANK
Short Box (Lt. Duty) 98 L (26 gal.)*
Long Box (Lt. Duty) 132 L (35 gal.)*
ENGINE OIL WITH FILTER
3.7L 4.7 L (5.0 qts.)
4.7L 5.6 L (6.0 qts.)
5.7L 6.6 L (7.0 qts.)
5.9L 4.7 L (5.0 qts.)
8.0L 6.6 L (7.0 qts.)
5.9L DIESEL 10.4 L (11.0 qts.)
2DESCRIPTION SPECIFICATION
COOLING SYSTEM
3.7L 15.4 L (16.2 qts.)**
4.7L 15.4 L (16.2 qts.)**
5.7L 15.4L (16.2 qts.)**
5.9L 15.5 L (16.3 qts.)**
8.0L 24L (24.3 qts.)**
5.9L Diesel Engine 28L (29.5 qts.)**
POWER STEERING
Power steering fluid capacities are dependent on engine/
chassis options as well as steering gear/cooler options.
Depending on type and size of internal cooler, length and
inside diameter of cooler lines, or use of an auxiliary cooler,
these capacities may vary. Refer to 19, Steering for proper
fill and bleed procedures.
AUTOMATIC TRANSMISSION
Service Fill - 46RE 3.8 L (4.0 qts.)
O-haul - 46RE 9-9.5L (19-20 pts.)L
Service Fill - 45RFE/
545RFE4X2 - 5.2 L (11.0 pts.)
4X4 - 6.2 L (13.0 pts.)
O-haul - 45RFE/545RFE 14-16 L (29-33 pts.)L
LDry fill capacity Depending on type and size of internal
cooler, length and inside diameter of cooler lines, or use of
an auxiliary cooler, these figures may vary. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC/FLUID -
STANDARD PROCEDURE)
MANUAL TRANSMISSION
NV3500 4X2 2.3 L (4.8 pts.)
NV3500 4X4 2.0 L (4.2 pts.)
NV4500 3.8 L (8.0 pts.)
NV5600 4.5 L (9.5 pts.)
TRANSFER CASE
NV241 GENII 1.6 L (3.4 pts.)
NV243 1.6 L (3.4 pts.)
NV271 1.89 L (4.0 pts.)
NV273 1.89 L (4.0 pts.)
FRONT AXLE   .03 L (1 oz)
C205F 1.66 L (3.5 pts.)
9 1/4 AA 2.25 L (4.75 pts.)
REAR AXLE   .03 L (1 oz)
9 1/4 2.32 L (4.9 pts.)***
10 1/2 AA 2.25 L (4.75 pts.)
11 1/2 AA 3.62 L (7.65 pts)
*** With Trac-Lok add 118 ml (4 oz.) of Limited Slip Additive.
** Includes 0.9L (1.0 qts.) for coolant reservoir.
*Nominal refill capacities are shown. A variation may be
observed from vehicle to vehicle due to manufacturing
tolerance and refill procedure.
DRLUBRICATION & MAINTENANCE 0 - 5
FLUID TYPES (Continued)

MAINTENANCE SCHEDULES
DESCRIPTION
Maintenance Schedule Information not included in
this section, is located in the appropriate Owner's
Manual.
There are two maintenance schedules that show
therequiredservice for your vehicle.
First is ScheduleªBº. It is for vehicles that are
operated under the conditions that are listed below
and at the beginning of the schedule.
²Day or night temperatures are below 0É C (32É
F).
²Stop and go driving.
²Extensive engine idling.
²Driving in dusty conditions.
²Short trips of less than 16 km (10 miles).
²More than 50% of your driving is at sustained
high speeds during hot weather, above 32É C (90É F).
²Trailer towing.
²Taxi, police, or delivery service (commercial ser-
vice).
²Off-road or desert operation.
²If equipped for and operating with E-85
(ethanol) fuel.
NOTE: Most vehicles are operated under the condi-
tions listed for Schedule(B(.
Second is ScheduleªAº. It is for vehicles that are
not operated under any of the conditions listed under
Schedule9B9.
Use the schedule that best describes your driving
conditions. Where time and mileage are listed, follow
the interval that occurs first.
CAUTION: Failure to perform the required mainte-
nance items may result in damage to the vehicle.
At Each Stop for Fuel
²Check the engine oil level about 5 minutes after
a fully warmed engine is shut off. Checking the oil
level while the vehicle is on level ground will
improve the accuracy of the oil level reading. Add oil
only when the level is at or below the ADD or MIN
mark.
²Check the windshield washer solvent and add if
required.
Once a Month
²Check tire pressure and look for unusual wear
or damage.
²Inspect the battery and clean and tighten the
terminals as required.
²Check the fluid levels of coolant reservoir, brake
master cylinder, power steering and transmission
and add as needed.
²Check all lights and all other electrical items for
correct operation.
At Each Oil Change
²Change the engine oil filter.
²Inspect the exhaust system.
²Inspect the brake hoses.
²Inspect the CV joints (if equipped) and front sus-
pension components.
²Check the automatic transmission fluid level.
²Check the manual transmission fluid level.
²Check the coolant level, hoses, and clamps.
²Rotate the tires at each oil change interval
shown on Schedule ªAº 10 000 km (6,000 miles) or
every other interval shown on Schedule ªBº 10 000
km (6,000 miles).
Schedule ªBº
Follow schedule ªBº if you usually operate your
vehicle under one or more of the following conditions.
²Day or night temperatures are below 0É C (32É
F).
²Stop and go driving.
²Extensive engine idling.
²Driving in dusty conditions.
²Short trips of less than 16 km (10 miles).
²More than 50% of your driving is at sustained
high speeds during hot weather, above 32É C (90É F).
²Trailer towing.
²Taxi, police, or delivery service (commercial ser-
vice).
²Off-road or desert operation.
²If equipped for and operating with E-85
(ethanol) fuel.
0 - 6 LUBRICATION & MAINTENANCEDR

Schedule ªAº
Miles 6,000 12,000 18,000 24,000 30,000
(Kilometers) (10 000) (19 000) (29 000) (38 000) (48 000)
[Months] [6] [12] [18] [24] [30]
Change engine oil and engine oil filter.XXXX X
Check transfer case fluid level.X
Lubricate outer tie rod ends 2500/3500
(4X4) models only.XXXX X
Inspect brake linings. X
Replace engine air cleaner filter.X
Replace spark plugs.X
Miles 36,000 42,000 48,000 54,000 60,000 66,000
(Kilometers) (58 000) (67 000) (77 000) (84 000) (96 000) (106 000)
[Months] [36] [42] [48] [54] [60] [66]
Change engine oil and engine
oil filter.XXXXX
X
Check transfer case fluid
level.X
Lubricate outer tie rod ends
2500/3500 (4X4) models only.XXXXX X
Flush and replace engine
coolant at 60 months,
regardless of mileage.X
Inspect brake linings. X X
Replace engine air cleaner
filter.X
Replace spark plugs.X
Inspect PCV valve, replace
as necessary.X*
Replace ignition cables
(5.7L/5.9L/8.0L).X
DRLUBRICATION & MAINTENANCE 0 - 11
MAINTENANCE SCHEDULES (Continued)

Miles 72,000 78,000 84,000 90,000 96,000 100,000
(Kilometers) (115 000) (125 000) (134 000) (144 000) (154 000) (160 000)
[Months] [72] [78] [84] [90] [96]
Change engine oil and engine oil filter.XXXXX
Lubricate outer tie rod ends 2500/3500
(4X4) models only.XXXXX
Drain and refill transfer case fluid. X
Flush and replace engine coolant, if not
done at 60 mos.X
Flush and replace Power Steering Fluid.X
Inspect brake linings. X X
Replace engine air cleaner filter.X
Replace spark plugs.X
Replace ignition cables (5.7L/5.9L/
8.0L).X
Inspect PCV valve, replace as
necessary.X*
Inspect auto tension drive belt and
replace if required (3.7L/4.7L/5.7L/5.9L/
8.0L).X
Drain and refill automatic tranmission
fluid, change filter and adjust bands
(46RE/47RE/48RE).X
Drain and refill automatic tranmission
fluid and change main sump filter and
spin-on cooler return filter (if equipped)
[45RFE/545RFE only].X
Miles 102,000 108,000 114,000 120,000
(Kilometers) (163 000) (173 000) (182 000) (192 000)
[Months] [102] [108] [114] [120]
Change engine oil and engine oil filter. X X X X
Check transfer case fluid level.X
Lubricate outer tie rod ends 2500/3500 (4X4) models only. X X X X
Inspect brake linings. X
Inspect auto tension drive belt and replace if required
(3.7L/4.7L/5.7L/5.9L/8.0L).X³X³
Replace engine air cleaner filter.X
Replace spark plugs.X
* This maintenance is recommended by the manu-
facture to the owner but is not required to maintain
the emissions warranty.
³ This maintenance is not required if previously
replaced.
Inspection and service should also be performed
anytime a malfunction is observed or suspected.
Retain all receipts.WARNING: You can be badly injured working on or
around a motor vehicle. Do only that service work
for which you have the knowledge and the right
equipment. If you have any doubt about your ability
to perform a service job, take your vehicle to a
competent mechanic.
0 - 12 LUBRICATION & MAINTENANCEDR
MAINTENANCE SCHEDULES (Continued)

COOLING
TABLE OF CONTENTS
page page
COOLING
DESCRIPTION
DESCRIPTION - COOLING SYSTEM FLOW
3.7L/4.7L ENGINE......................1
DESCRIPTION - COOLING SYSTEM FLOW -
5.9L ENGINE..........................1
DESCRIPTIONÐCOOLING SYSTEM FLOW -
5.9L DIESEL..........................2
DESCRIPTION - HOSE CLAMPS...........3
OPERATION
OPERATIONÐCOOLING SYSTEM.........3
OPERATIONÐHOSE CLAMPS............5
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐON-BOARD
DIAGNOSTICS (OBD)...................5
DIAGNOSIS AND TESTINGÐCOOLING
SYSTEM - TESTING FOR LEAKS..........5
DIAGNOSIS AND TESTING - COOLING
SYSTEM DIESEL ENGINE................7
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS............................10
STANDARD PROCEDURE
STANDARD PROCEDURE - COOLANT
LEVEL CHECK........................17STANDARD PROCEDURE - COOLING
SYSTEM CLEANING/REVERSE FLUSHING . . 17
STANDARD PROCEDUREÐDRAINING
COOLING SYSTEM 3.7L/4.7L/5.7L ENGINE . . 18
STANDARD PROCEDURE - REFILLING
COOLING SYSTEM 3.7L/4.7L/5.7L ENGINE . . 18
STANDARD PROCEDUREÐDRAINING
COOLING SYSTEM 5.9L/8.0L ENGINE......18
STANDARD PROCEDUREÐREFILLING
COOLING SYSTEM 5.9L/8.0L ENGINE......18
STANDARD PROCEDUREÐDRAINING
COOLING SYSTEM 5.9L DIESEL ENGINE . . . 19
STANDARD PROCEDUREÐREFILLING
COOLING SYSTEM 5.9L DIESEL ENGINE . . . 19
STANDARD PROCEDURE - ADDING
ADDITIONAL COOLANT.................19
SPECIFICATIONS
TORQUE............................20
SPECIFICATIONS -....................20
SPECIAL TOOLS
COOLING...........................20
ACCESSORY DRIVE......................22
ENGINE...............................35
TRANSMISSION.........................72
COOLING
DESCRIPTION
DESCRIPTION - COOLING SYSTEM FLOW
3.7L/4.7L ENGINE
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre-
vents overheating.
The cooling system provides a means of heating
the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system is pressurized and uses a centrifugal water
pump to circulate coolant through the system and a
coolant deaeration and reserve system that utilizes a
pressurized degas bottle (hot bottle).
An optional factory installed maximum duty cool-
ing package is available on most models. This pack-
age will provide additional cooling capacity forvehicles used under extreme conditions such as
trailer towing in high ambient temperatures (Fig. 1).
DESCRIPTION - COOLING SYSTEM FLOW -
5.9L ENGINE
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre-
vents overheating.
The cooling system also provides a means of heat-
ing the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system uses a coolant recovery / reserve system that
utilizes an ambient overflow bottle.
An optional factory installed maximum duty cool-
ing package is available on most models. This pack-
age will provide additional cooling capacity for
vehicles used under extreme conditions such as
trailer towing in high ambient temperatures (Fig. 2).
DRCOOLING 7 - 1

system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
5.9L, 5.9L Diesel, and 8.0L engines utilize an
ambient overflow bottle for coolant recovery/reserve.
The 3.7L and 4.7L engines utilize a pressurized
degas bottle for coolant deaeration and reserve. This
degas bottle has coolant flowing through it continu-
ously, supplied by a vent in the hot side radiator
tank and returning to the heater return hose.
An optional factory installed maximum duty cool-
ing package is available on most models. This pack-
age will provide additional cooling capacity for
vehicles used under extreme conditions such as
trailer towing in high ambient temperatures.
OPERATIONÐHOSE CLAMPS
The spring type hose clamp applies constant ten-
sion on a hose connection. To remove a spring type
hose clamp, only use constant tension clamp pliers
designed to compress the hose clamp.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐON-BOARD
DIAGNOSTICS (OBD)
COOLING SYSTEM RELATED DIAGNOSTICS
The Engine Control Module (ECM) has been pro-
grammed to monitor certain cooling system compo-
nents:
²If the engine has remained cool for too long a
period, such as with a stuck open thermostat, a Diag-
nostic Trouble Code (DTC) can be set.²If an open or shorted condition has developed in
the electronically controlled viscous fan clutch circuit,
a Diagnostic Trouble Code (DTC) can be set.
²If fan speed is not detected a DTC will be set.
²Coolant temperature sensor circuit problems can
set a DTC.
If the problem is sensed in a monitored circuit
often enough to indicated an actual problem, a DTC
is stored. The DTC will be stored in the ECM mem-
ory for eventual display to the service technician.
(Refer to 25 - EMISSIONS CONTROL - DESCRIP-
TION).
ACCESSING DIAGNOSTIC TROUBLE CODES
To read DTC's and to obtain cooling system data,
(Refer to 25 - EMISSIONS CONTROL - DESCRIP-
TION).
ERASING TROUBLE CODES
After the problem has been repaired, use the
DRBIIItscan tool to erase a DTC. Refer to the
appropriate Powertrain Diagnostic Procedures ser-
vice information for operation of the DRBIIItscan
tool.
DIAGNOSIS AND TESTINGÐCOOLING SYSTEM
- TESTING FOR LEAKS
ULTRAVIOLET LIGHT METHOD
A leak detection additive is available through the
parts department that can be added to cooling sys-
tem. The additive is highly visible under ultraviolet
light (black light). Pour one ounce of additive into
cooling system. Place heater control unit in HEAT
position. Start and operate the engine until the radi-
ator upper hose is warm to the touch. Aim the com-
mercially available black light tool at the components
to be checked. If leaks are present, the black light
will cause the additive to glow a bright green color.
The black light can be used in conjunction with a
pressure tester to determine if any external leaks
exist (Fig. 5).
PRESSURE TESTER METHOD
The engine should be at normal operating temper-
ature. Recheck the system cold if the cause of coolant
loss is not located during the warm engine examina-
tion.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING.
Carefully remove the radiator pressure cap from
the filler neck and check the coolant level. Push
down on the cap to disengage it from the stop tabs.
Wipe the inside of the filler neck and examine the
Fig. 4 Spring Clamp Size Location
1 - SPRING CLAMP SIZE LOCATION
DRCOOLING 7 - 5
COOLING (Continued)

WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
Drain sufficient coolant to allow thermostat
removal. (Refer to 7 - COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT - REMOVAL). Remove
accessory drive belt (Refer to 7 - COOLING/ACCES-
SORY DRIVE/DRIVE BELTS - REMOVAL).
Add coolant to radiator to bring level to within 6.3
mm (1/4 in) of the top of the thermostat housing.CAUTION: Avoid overheating. Do not operate
engine for an excessive period of time. Open drain-
cock immediately after test to eliminate boil over.
Start engine and accelerate rapidly three times, to
approximately 3000 rpm while observing coolant. If
internal engine combustion gases are leaking into
cooling system, bubbles will appear in coolant. If bub-
bles do not appear, internal combustion gas leakage
is not present.
DIAGNOSIS AND TESTING - COOLING SYSTEM
DIESEL ENGINE
COOLING SYSTEM DIAGNOSISÐDIESEL ENGINE
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS
LOWNOTE:
Information on dash cluster is
displayed based on broadcast data
from ECM. DTC will be set for
engine sensor circuit concern.1. Vehicle is equipped with a heavy
duty cooling system.1. None. System operating normally.
2. Thermostat stuck open 2. Inspect and test thermostat.
3. Coolant level low. 3. Fill cooling system. (Refer to 7 -
COOLING - STANDARD
PROCEDURE)
4. Temperature gauge not
functioning correctly.4. Check cluster (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
DRCOOLING 7 - 7
COOLING (Continued)

COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
READS LOW1. Has a Diagnostic Trouble
Code (DTC) been set indicating
a stuck open thermostat?1. (Refer to 25 - EMISSIONS CONTROL -
DESCRIPTION) for On-Board Diagnostics
and DTC information. Replace thermostat
if necessary.
2. Is the temperature sending
unit connected?2. Check the temperature sensor
connector. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - SCHEMATIC -
ELECTRICAL) Repair connector if
necessary.
3. Is the temperature gauge
operating OK?3. Check gauge operation. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/
ENGINE TEMPERATURE GAUGE -
DESCRIPTION). Repair as necessary.
4. Coolant level low in cold
ambient temperatures
accompanied with poor heater
performance.4. Check coolant level in the coolant
reserve/overflow tank or degas bottle and
the radiator. Inspect system for leaks.
Repair leaks as necessary. Refer to the
Coolant section of the manual text for
WARNINGS and CAUTIONS associated
with removing the radiator cap.
5. Improper operation of internal
heater doors or heater controls.5. Inspect heater and repair as necessary.
(Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND
TESTING) for procedures.
DRCOOLING 7 - 11
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
READS HIGH OR THE
COOLANT WARNING LAMP
ILLUMINATES. COOLANT MAY
OR MAY NOT BE LOST OR
LEAKING FROM THE COOLING
SYSTEM1. Trailer is being towed, a steep
hill is being climbed, vehicle is
operated in slow moving traffic,
or engine is being idled with
very high ambient (outside)
temperatures and the air
conditioning is on. Higher
altitudes could aggravate these
conditions.1. This may be a temporary condition and
repair is not necessary. Turn off the air
conditioning and attempt to drive the
vehicle without any of the previous
conditions. Observe the temperature
gauge. The gauge should return to the
normal range. If the gauge does not return
to the normal range, determine the cause
for overheating and repair. Refer to
Possible Causes (2-18).
2. Is the temperature gauge
reading correctly?2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER -
SCHEMATIC - ELECTRICAL). Repair as
necessary.
3. Is the temperature warning
illuminating unnecessarily?3. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - SCHEMATIC -
ELECTRICAL).
4. Coolant low in coolant
reserve/overflow tank and
radiator?4. Check for coolant leaks and repair as
necessary. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
5. Pressure cap not installed
tightly. If cap is loose, boiling
point of coolant will be lowered.
Also refer to the following Step
6.5. Tighten cap
6. Poor seals at the radiator
cap.6. (a) Check condition of cap and cap
seals. Refer to Radiator Cap. Replace cap
if necessary.
(b) Check condition of radiator filler neck.
If neck is bent or damaged, replace
radiator (5.9L) or degas bottle (3.7L, 4.7L).
7. Coolant level low in radiator
but not in coolant reserve/
overflow tank. This means the
radiator is not drawing coolant
from the coolant reserve/
overflow tank as the engine
cools (5.9L).7. (a) Check condition of radiator cap and
cap seals. Refer to Radiator Cap in this
Group. Replace cap if necessary.
(b) Check condition of radiator filler neck.
If neck is bent or damaged, replace
radiator.
(c) Check condition of the hose from the
radiator to the coolant tank. It should fit
tight at both ends without any kinks or
tears. Replace hose if necessary.
(d) Check coolant reserve/overflow tank
and tanks hoses for blockage. Repair as
necessary.
8. Incorrect coolant
concentration8. Check coolant. (Refer to LUBRICATION
& MAINTENANCE/FLUID TYPES -
DESCRIPTION).
9. Coolant not flowing through
system9. Check for coolant flow at radiator filler
neck with some coolant removed, engine
warm and thermostat open. Coolant
should be observed flowing through
radiator. If flow is not observed, determine
area of obstruction and repair as
necessary.
7 - 12 COOLINGDR
COOLING (Continued)