Establish what driving conditions caused the complaint.
Consult Trailer Towing section of owners manual.
Do not exceed limits.
A maximum cooling package should have been
ordered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system components
should be installed for model involved per
manufacturer's specifications.
Determine if any recent service has been performed
on vehicle that may effect cooling system.
These charts are to be used as a quick-reference
only. Refer to the group text for information.
CONDITION |
POSSIBLE CAUSES |
CORRECTION |
TEMPERATURE GAUGE READS
LOW |
- Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open thermostat?
- Is the temperature sending unit
connected?
- Is the temperature gauge
operating OK?
- Coolant level low in cold ambient
temperatures accompanied with
poor heater performance.
- Improper operation of internal
heater doors or heater controls
|
- Refer to Group 25, Emission
Systems for On-Board Diagnostics
and DTC information. Replace
thermostat if necessary.
- Check the temperature sensor
connector. Refer to Group 8E.
Repair connector if necessary.
- Check gauge operation. Refer to
Group 8E. Repair as necessary.
- Check coolant level in the coolant
reserve/overflow tank 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..
- Inspect heater and repair as
necessary. Refer to Group 24,
Heating and Air Conditioning for
procedures.
|
TEMPERATURE GAUGE READS
HIGH OR THE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST OR LEAKING FROM THE
COOLING SYSTEM |
- 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.
- Is the temperature gauge reading
correctly?
- Is the temperature warning
illuminating unnecessarily?
- Coolant low in coolant reserve/
overflow tank and radiator?
- Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following Step 6.
- Poor seals at the radiator cap.
- 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
- Incorrect coolant concentration
- Coolant not flowing through
system
- Radiator or A/C condenser fins
are dirty or clogged.
- Radiator core is corroded or
plugged.
- Aftermarket A/C installed
without proper radiator.
- Fuel or ignition system
problems.
- Dragging brakes.
- Bug screen or cardboard is
being used, reducing airflow.
- Thermostat partially or
completely shut.
- Viscous fan drive not operating
properly.
- Electric cooling fan not
operating properly (vehicles
equipped with 2.5L/4.0L and air
conditioning
- Cylinder head gasket leaking.
- Heater core leaking.
|
- 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 (2-20).
- Check gauge. Refer to Group 8E.
Repair as necessary.
- Check warning lamp operation.
Refer to Group 8E. Repair as
necessary.
- Check for coolant leaks and
repair as necessary. Refer to
Testing Cooling System for Leaks in
this Group.
- Tighten cap
- (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.
- (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.
- Check coolant. Refer to Coolant
section in this Group for correct
coolant/water mixture ratio.
- 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.
- Remove insects and debris.
Refer to Radiator Cleaning in this
Group.
- Have radiator re-cored or
replaced.
- Install proper radiator.
- Refer to Fuel and Ignition
System Groups for diagnosis.
- Check and correct as
necessary. Refer to Group 5,
Brakes for correct procedures.
- Remove bug screen or
cardboard.
- Check thermostat operation and
replace as necessary. Refer
- Check fan drive operation and
replace as necessary. Refer to
Viscous Fan Drive in this Group.
- Check electric fan operation and
repair as necessary. Refer to
Electric Cooling Fan in this Group
- Check for cylinder head gasket
leaks. Refer to Cooling System-
Testing For Leaks in this Group. For
repair, refer to Group 9, Engines.
- Check heater core for leaks.
Refer to Group 24, Heating and Air
Conditioning. Repair as necessary.
|
TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC) |
- On vehicles equipped with an
electric fan, the gauge may cycle
up and down. This is due to the
cycling of the electric radiator fan.
- During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly.
- Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.
- Gauge reading rises when
vehicle is brought to a stop after
heavy use (engine still running)
- Gauge reading high after
re-starting a warmed up (hot)
engine.
- Coolant level low in radiator (air
will build up in the cooling system
causing the thermostat to open
late).
- Cylinder head gasket leaking
allowing exhaust gas to enter
cooling system causing a
thermostat to open late.
- Water pump impeller loose on
shaft.
- Loose accessory drive belt.
(water pump slipping)
- Air leak on the suction side of
the water pump allows air to build
up in cooling system causing
thermostat to open late.
|
- This is a normal condition. No
correction is necessary unless the
gauge cycles into the red (overheat)
zone. Refer to Electric Cooling Fan
Diagnosis and Testing in this group.
- A normal condition. No correction
is necessary.
- Check operation of gauge and
repair if necessary. Refer to Group
8E, Instrument Panel and Gauges.
- A normal condition. No correction
is necessary. Gauge should return
to normal range after vehicle is
driven.
- A normal condition. No correction
is necessary. The gauge should
return to normal range after a few
minutes of engine operation.
- Check and correct coolant leaks.
Refer to Cooling System-Testing for
leaks in this group.
- (a) Check for cylinder head
gasket leaks. Refer to Cooling
System-Testing for Leaks in this
group.
(b) Check for coolant in the engine
oil. Inspect for white steam emitting
from the exhaust system. Repair as
necessary.
- Check water pump and replace
as necessary. Refer to water Pumps
in this group.
- Refer to Accessory Drive Belts in
this group. Check and correct as
necessary.
- Locate leak and repair as
necessary.
|
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
TO COOLANT TANK.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK |
- Pressure relief valve in radiator
cap is defective.
|
- Check condition of radiator cap
and cap seals. Refer to Radiator
Caps in this group. Replace cap as
necessary.
|
COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE READING
HIGH OR HOT |
- Coolant leaks in radiator, cooling
system hoses, water pump or
engine.
|
- Pressure test and repair as
necessary. Refer to Cooling
System-Testing For Leaks in this
group.
|
DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY OR MAY
NOT BE READING HIGH |
- engine overheating.
- Freeze point of coolant not
correct. Mixture is too rich or too
lean.
|
- Check reason for overheating
and repair as necessary.
- Check coolant concentration.
Refer to the Coolant section of this
group and adjust ratio as required.
|
HOSE OR HOSES COLLAPSE
WHILE ENGINE IS RUNNING |
- Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
reserve/overflow system.
|
- (a) Radiator cap relief valve
stuck. Refer to Radiator Cap in this
group. Replace if necessary
(b) Hose between coolant
reserve/overflow tank and radiator is
kinked. Repair as necessary.
(c) Vent at coolant reserve/overflow
tank is plugged. Clean vent and
repair as necessary.
(d) Reserve/overflow tank is
internally blocked or plugged. Check
for blockage and repair as
necessary.
|
ELECTRIC RADIATOR FAN RUNS
ALL OF THE TIME (2.5L/4.0L
MODELS EQUIPPED WITH A/C
AND 4.0L MODELS EQUIPPED
WITH MAX COOLING) |
- Fan relay, powertrain control
module (PCM) or coolant
temperature sensor defective.
|
- Refer to Electric Cooling Fan
Diagnosis and Testing. Also refer to
Group 8W, Wiring Diagrams. Repair
as necessary.
|
ELECTRIC RADIATOR FAN WILL
NOT RUN AT ALL. GAUGE
READING HIGH OR HOT
(2.5L/4.0L MODELS EQUIPPED
WITH A/C AND 4.0L MODELS
EQUIPPED WITH MAX COOLING) |
- Blown Fuse in Power Distribution
Center (PDC)
- Fan relay, powertrain control
module (PCM) or coolant
temperature sensor defective.
- Fan Motor Defective
|
- Determine reason for blown fuse
and repair as necessary.
- Refer to Electric Cooling Fan
Diagnosis and Testing. Also refer to
Group 8W, Wiring Diagrams. Repair
as necessary.
- Refer to Electric Cooling Fan
Diagnosis and Testing. Also refer to
Group 8W, Wiring Diagrams. Repair
as necessary.
|
NOISY VISCOUS FAN/DRIVE |
- Fan blades loose.
- Fan blades striking a surrounding
object.
- Air obstructions at radiator or air
conditioning condenser.
- Thermal viscous fan drive has
defective bearing.
- A certain amount of fan noise
may be evident on models
equipped with a thermal viscous fan
drive. Some of this noise is normal.
|
- Replace fan blade assembly.
Refer to Cooling System Fans in
this Group
- Locate point of fan blade contact
and repair as necessary.
- Remove obstructions and/or
clean debris or insects from radiator
or A/C condenser.
- Replace fan drive. Bearing is not
serviceable. Refer to Viscous Fan
Drive in this group.
- Refer to Viscous Fan Drive in this
group for an explanation of normal
fan noise.
|
INADEQUATE HEATER
PERFORMANCE. THERMOSTAT
FAILED IN OPEN POSITIO |
- Has a Diagnostic trouble Code
(DTC) been set?
- Coolant level low
- Obstructions in heater hose/
fittings
- Heater hose kinked
- Water pump is not pumping
water to/through the heater core.
When the engine is fully warmed
up, both heater hoses should be
hot to the touch. If only one of the
hoses is hot, the water pump may
not be operating correctly or the
heater core may be plugged.
Accessory drive belt may be
slipping causing poor water pump
operation.
|
- Refer to Group 25, Emissions for
correct procedures and replace
thermostat if necessary
- Refer to Cooling System-Testing
For Leaks in this group.
- Remove heater hoses at both
ends and check for obstructions
- Locate kinked area and repair as
necessary
- Refer to Water Pump in this
group. If a slipping belt is detected,
refer to Accessory Drive Belts in this
group. If heater core obstruction is
detected, refer to Group 24, Heating
and Air Conditioning.
|
STEAM IS COMING FROM THE
FRONT OF VEHICLE NEAR THE
GRILL AREA WHEN WEATHER IS
WET, ENGINE IS WARMED UP
AND RUNNING, AND VEHICLE IS
STATIONARY. TEMPERATURE
GAUGE IS IN NORMAL RANGE |
- During wet weather, moisture
(snow, ice or rain condensation) on
the radiator will evaporate when the
thermostat opens. This opening
allows heated water into the
radiator. When the moisture
contacts the hot radiator, steam
may be emitted. This usually occurs
in cold weather with no fan or
airflow to blow it away.
|
- Occasional steam emitting from
this area is normal. No repair is
necessary
|
COOLANT COLOR |
- Coolant color is not necessarily
an indication of adequate corrosion
or temperature protection. Do not
rely on coolant color for determining
condition of coolant.
|
- Refer to Coolant in this group for
coolant concentration information.
Adjust coolant mixture as
necessary.
|
COOLANT LEVEL CHANGES IN
COOLANT RESERVE/OVERFLOW
TANK. TEMPERATURE GAUGE IS
IN NORMAL RANGE |
- Level changes are to be
expected as coolant volume
fluctuates with engine temperature.
If the level in the tank was between
the FULL and ADD marks at normal
operating temperature, the level
should return to within that range
after operation at elevated
temperatures.
|
- A normal condition. No repair is
necessary
|