Dodge ram truck 3500 1996 Service Manual page 299

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COOLING SYSTEM 7 - 1 5
D I A G N O S I S A N D T E S T I N G ( C o n t i n u e d )
COOLING SYSTEM DIAGNOSIS
CONDITION
POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
READS LOW
1. Has a Diagnostic Trouble
Code (DTC) number 17 been
set indicating a stuck open
engine thermostat?
2. Is the temperature gauge
(if equipped) connected to the
temperature gauge coolant
sensor on the engine?
3. Is the temperature gauge
(if equipped) operating OK?
4. Coolant level low in cold
ambient temperatures
accompanied with poor heater
performance.
5. Improper operation of internal
heater doors or heater
controls.
1. Refer to On-Board Diagnostics in the
service manual text. Replace thermostat
if necessary. If a Diagnostic Trouble
Code (DTC) number 17 has not been set,
the problem may be with the temperature
gauge.
2. Check the engine temperature sensor
connector in the engine compartment.
Refer to Group 8E. Repair as necessary.
3. Check gauge operation. Refer to
Group 8E. Repair as necessary.
4. 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
precautions before removing the radiator
cap.
5. Inspect heater and repair as necessary.
Refer to Group 24, Heating and Air
Conditioning for procedures.
TEMPERATURE GAUGE
READS HIGH OR ENGINE
COOLANT WARNING LAMP
ILLUMINATES. COOLANT
MAY OR MAY NOT
BE
LOST OR LEAKING FROM
COOLING SYSTEM
1. 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.
2. Is temperature gauge
(if equipped) reading correctly?
3. Is temperature warning lamp
(if equipped) illuminating
unnecessarily?
4. Coolant low in coolant
reserve/overflow tank and
radiator?
5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following step 6.
6. Poor seals at radiator cap.
t
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 normal range,
determine the cause for overheating and
repair. Refer to POSSIBLE CAUSES
(numbers 2 through 20).
2. Check gauge. Refer to Group 8E. Repair as
necessary.
3. Check warning lamp operation. Refer to
Group 8E. Repair as necessary.
4. Check for coolant leaks and repair as
necessary. Refer to Testing Cooling System
For Leaks in this group.
5. Tighten 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.
J9507-41