CONDITION
POSSIBLE CAUSES
CORRECTION
INADEQUATE HEATER PERFOR-
MANCE.
1. Has a diagnostic trouble code
(DTC) been set?
1. Refer to the appropriate Power-
train Diagnostic information. Repair
as necessary.
2. Coolant level low.
2. Adjust coolant level as neces-
sary. Check cooling system for
leaks. Repair as necessary.
3. Obstructions in heater hose fit-
ting at engine or at heater core.
3. Remove heater hoses at both
ends and check for obstructions.
Repair as necessary.
4. Heater hose kinked.
4. Locate kinked area and repair
as necessary.
5. Water pump is not pumping
coolant 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.
5. Replace water pump.
HEAT ODOR.
1. Various heat shields are used at
certain driveline components. One
or more of these shields may be
missing.
1. Locate missing shields and
replace or repair as necessary.
2. Is temperature gauge reading
above the normal range?
2. Refer to Gauge Is Reading High
in these Diagnosis Charts.
3. Is cooling fan operating cor-
rectly?
3. Refer to appropriate Diagnostic
Information. Repair as necessary.
4. Has undercoating been applied
to any unnecessary component?
4. Clean undercoating as neces-
sary.
5. Engine may be running rich,
causing the catalytic converter to
overheat.
5. Refer to appropriate Diagnostic
Information for operation of the
DRBIII
T
scan tool. Repair as nec-
essary.
POOR DRIVEABILITY (THERMO-
STAT LY STUCK OPEN). GAUGE
MAY BE READING LOW.
1. The engine thermostat must be
operating correctly for proper drive-
ability, clean vehicle emissions,
and the prevention of sludge
buildup in the engine oil. Has a
diagnostic trouble code been set?
1. Refer to appropriate Diagnostic
Information for operation of the
DRBIII
T
scan tool. Replace thermo-
stat, if necessary.
STEAM IS COMING FROM
FRONT OF VEHICLE NEAR
GRILL AREA WHEN WEATHER IS
WET, ENGINE WARMED UP AND
RUNNING WITH VEHICLE STA-
TIONARY, OR JUST SHUT OFF.
TEMPERATURE GAUGE IS NOR-
MAL.
1. During wet weather, moisture
(snow, ice, rain, or condensation)
on the radiator will evaporate when
the thermostat opens. The thermo-
stat opening allows heated coolant
into the radiator. When the mois-
ture contacts the hot radiator,
steam may be emitted. This usu-
ally occurs in cold weather with no
fan or air flow to blow it away.
1. Occasional steam emitting from
this area is normal. No repair is
necessary.
7 - 8
ENGINE
ZB
ENGINE (Continued)