NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR 1.3, MZR 1.5]

id0103d7802300

17

COOLING SYSTEM CONCERNS—OVERHEATING

DESCRIPTION

•  The engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

•  Radiator hoses damage

•  Coolant leakage

―  Leakage around heater unit

―  Leakage at coolant hoses and/or radiator

•  Improper coolant level

•  Fans reverse rotation

•  Fuse malfunction

•  Coolant overflow system malfunction

•  Poor radiator condition

•  Improper or damaged radiator cap

•  Improper water/anti-freeze mixture

•  PCM DTC is stored

•  Improper operation of A/C system

―  Climate control system malfunction

―  Refrigerant pressure switch related wiring harness malfunction

•  Excessive A/C system pressure

•  Improper operation of cooling fan control system

•  Improper tension of drive belt

•  Thermostat malfunction

•  Improper indication of low engine coolant temperature indicator light

―  ECT sensor malfunction

―  Instrument cluster malfunction

•  PCM malfunction

17	COOLING SYSTEM CONCERNS—OVERHEATING
DESCRIPTION	• The engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Radiator hoses damage • Coolant leakage ― Leakage around heater unit ― Leakage at coolant hoses and/or radiator • Improper coolant level • Fans reverse rotation • Fuse malfunction • Coolant overflow system malfunction • Poor radiator condition • Improper or damaged radiator cap • Improper water/anti-freeze mixture • PCM DTC is stored • Improper operation of A/C system ― Climate control system malfunction ― Refrigerant pressure switch related wiring harness malfunction • Excessive A/C system pressure • Improper operation of cooling fan control system • Improper tension of drive belt • Thermostat malfunction • Improper indication of low engine coolant temperature indicator light ― ECT sensor malfunction ― Instrument cluster malfunction • PCM malfunction

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	INSPECT RELATED PART CONDITION • Inspect the following: ― Collapsed or restricted radiator hoses ― Coolant leakage ― Engine coolant level ― Fan rotational direction ― Fuses ― Overflow system ― Radiator condition ― Radiator pressure cap ― Water and anti-freeze mixture • Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
1		No	Go to the next step.
2	VERIFY PCM DTC • Perform the KOEO and KOER self test. (See KOEO/KOER SELF TEST [MZR 1.3, MZR 1.5].) • Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [MZR 1.3, MZR 1.5].)
2		No	Go to the next step.
3	DETERMINE IF MALFUNCTION CAUSE IS A/C SYSTEM OR OTHER • Start the engine and idle it. • Turn the A/C switch off. • Does the A/C compressor disengaged?	Yes	Go to the next step.
3		No	Go to the symptom troubleshooting “NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”. (See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR 1.3, MZR 1.5].)
4	INSPECT COOLING FAN CONTROL SYSTEM OPERATION • Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.3, MZR 1.5].) • Does the cooling fan control system operate properly?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning part according to the inspection results.
5	INSPECT DRIVE BELT • Inspect the drive belt. (See DRIVE BELT INSPECTION [MZR 1.3, MZR 1.5].) • Is there any malfunction?	Yes	Replace the drive belt. (See DRIVE BELT REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
5		No	Go to the next step.
6	INSPECT COOLANT LEAKAGE AT HEATER UNIT • Visually inspect for leakage around heater unit in passenger compartment. • Is there any leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results.
6		No	Go to the next step.
7	INSPECT COOLANT LEAKAGE AT COOLING SYSTEM PART • Visually inspect for leakage at coolant hoses and/or radiator. • Is there any leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results.
7		No	Go to the next step.
8	INSPECT ECT SENSOR SIGNAL • Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 1.3, MZR 1.5].) • Compare the ECT PID and low engine coolant temperature indicator light on instrument cluster condition. • Is the ECT PID value same as indicator light readings?	Yes	Go to the next step.
8		No	Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR 1.3, MZR 1.5].) • If there is any malfunction: ― Replace the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].) • If there is no malfunction: ― Inspect the instrument cluster. (See INSTRUMENT CLUSTER INSPECTION.) Replace the instrument cluster if necessary. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)
9	INSPECT THERMOSTAT • Cool down the engine. • Remove the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].) • Inspect the thermostat operation. (See THERMOSTAT INSPECTION [MZR 1.3, MZR 1.5].) • Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
9		No	The thermostat is normal. • Inspect the engine block for leakage or blockage. • Repair or replace the malfunctioning part according to the inspection results.
10	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 1.3, MZR 1.5].) • If the malfunction remains, inspect the related Service Information and perform the repair or diagnosis. ― If the vehicle is repaired, troubleshooting is completed. ― If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)