Cooling System Diagnostic Chart - Jeep 200 Cherokee Service Manual

7 - 12 COOLING SYSTEM
DIAGNOSIS AND TESTING (Continued)
CONDITION
TEMPERATURE GAUGE READS
LOW
TEMPERATURE GAUGE READS
HIGH OR THE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST OR LEAKING FROM THE
COOLING SYSTEM
COOLING SYSTEM DIAGNOSIS CHART
POSSIBLE CAUSES
1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open thermostat?
2. Is the temperature sending unit
connected?
3. Is the temperature gauge
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. 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 the temperature gauge reading
correctly?
3. Is the temperature warning
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.
CORRECTION
1. Refer to Group 25, Emission
Systems for On-Board Diagnostics
and DTC information. Replace
thermostat if necessary.
2. Check the temperature sensor
connector. Refer to Group 8E.
Repair connector if 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
CAUTIONS associated with
removing the radiator cap.
5. Inspect heater and repair as
necessary. Refer to Group 24,
Heating and Air Conditioning for
procedures.
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 (2-20).
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
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