Dodge RAM TRUCK 1500 1995 Service Manual page 280

7 - 10 COOLING SYSTEM DIAGNOSIS
COOLING SYSTEM DIAGNOSIS—ALL EXCEPT DIESEL—CONTINUED
B R
CONDITION POSSIBLE CAUSES
ORRECTION
INADEQUATE HEATER
PERFORMANCE.
THERMOSTAT FAILED IN
OPEN POSITION
1. Has a diagnostic trouble code
(DTC) number 17 been set?
2. Coolant level low.
3. Obstructions in heater hose
fittings at engine.
4. Heater hose kinked.
5. Some models with certain
engines are equipped with a
water control valve located on
one of the heater hoses. This
valve may be defective.
6. Water pump is not pumping
water to 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.
The accessory drive belt may
also be slipping causing poor
water pump operation.
1. Refer to On-Board Diagnostics in the
manual text and replace thermostat if
necessary.
2. Refer to Testing Cooling System For
Leaks in the manual text. Repair as
necessary.
3. Remove heater hoses at both ends and
check for obstructions. Repair as
necessary.
4. Locate kinked area and repair as
necessary.
5. Refer to Group 24, Heating and Air
Conditioning for diagnosis. Repair as
necessary.
6. Refer to Water Pumps in this group.
Repair as necessary. If a slipping belt is
detected, refer to Engine Accessory Drive
Belts in this group. Repair as necessary.
HEAT ODOR
1. Various heat shields are used at
certain drive line components.
One or more of these shields
may be missing.
2. Is temperature gauge reading
above the normal range?
3. Is cooling fan operating
correctly?
4. Has undercoating been applied
to any unnecessary component?
5. Engine may be running rich
causing the catalytic converter
to overheat.
1. Locate missing shields and replace or
repair as necessary.
2. Refer to the previous Temperature
Gauge Reads High in these Diagnosis
Charts. Repair as necessary.
3. Refer to Cooling System Fan in this
group for diagnosis. Repair as necessary.
4. Clean undercoating as necessary.
5. Refer to the DRB scan tool and the
appropriate Powertrain Diagnostic
Procedures service manual. Repair as
necessary.
POOR DRIVEABILITY
(THERMOSTAT POSSIBLY
STUCK OPEN). GAUGE
MAY BE READING LOW
1. For proper driveability, good
vehicle emissions and for
preventing build-up of engine oil
sludge, the thermostat must be
. operating properly. Has a
diagnostic trouble code (DTC)
number 17 been set?
1. Refer to On-Board Diagnostics in this
group. DTC's may also be checked using
the DRB scan tool. Refer to the proper
Powertrain Diagnostics Procedures
service manual for checking the
thermostat using the DRB scan tool.
Replace thermostat if necessary.
J9507-53