NO.19 COOLING SYSTEM CONCERNS-OVERHEATING [MZR-CD 2.2]

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19

COOLING SYSTEM CONCERNS—OVERHEATING

DESCRIPTION

•  Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

•  Cooling fan malfunction

•  Low drive belt tension

•  Drive belt damage

•  Improper coolant level

•  Thermostat malfunction

•  Radiator clogging

•  Improper water/anti-freeze mixture

•  Improper or damaged radiator cap

•  Radiator hose damage

•  Coolant leakage (engine internal, turbocharger, external)

•  A/C system malfunction

•  EGR system malfunction

•  Coolant heater system malfunction

•  Improper indication of water temperature gauge

―  ECT sensor malfunction

―  Instrument cluster malfunction

19	COOLING SYSTEM CONCERNS—OVERHEATING
DESCRIPTION	• Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Cooling fan malfunction • Low drive belt tension • Drive belt damage • Improper coolant level • Thermostat malfunction • Radiator clogging • Improper water/anti-freeze mixture • Improper or damaged radiator cap • Radiator hose damage • Coolant leakage (engine internal, turbocharger, external) • A/C system malfunction • EGR system malfunction • Coolant heater system malfunction • Improper indication of water temperature gauge ― ECT sensor malfunction ― Instrument cluster malfunction

Diagnostic Procedure

STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: • Engine coolant level • Coolant leakage (around heater unit in passenger compartment, coolant hoses and/or radiator, and around coolant heater unit.) • Water and anti-freeze mixture • Radiator condition • Collapsed or restricted radiator hoses • Radiator pressure cap • Drive belt tension • Drive belt • Fan rotational direction Are all items normal?	Yes	Go to the next step.
1		No	Service if necessary. Repeat Step 1.
2	Perform the KOEO or KOER self test. (See KOEO/KOER SELF TEST [MZR-CD 2.2].) Are any DTCs displayed?	Yes	DTC is displayed: • Go to the applicable DTC inspection. (See DTC TABLE [MZR-CD 2.2].) Communication error message is displayed: • Open circuit in wiring harness between main relay terminal E and PCM terminal 2I • Open circuit in wiring harness between main relay terminal C and PCM terminals 2C, 2F • Main relay is stuck open. • Open or poor ground circuit (PCM terminals 2A, 2B, 2D and 2E) • Poor connection of vehicle body ground
2		No	Go to the next step.
3	Start the engine and run it at idle speed. 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.26 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”. (See NO.26 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD 2.2].)
4	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD 2.2].) Does the cooling fan control operate properly?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning part according to the inspection results.
5	Inspect the drive belt. (See DRIVE BELT INSPECTION [MZR-CD 2.2].) Is there any malfunction?	Yes	Replace the drive belt. (See DRIVE BELT REMOVAL/INSTALLATION [MZR-CD 2.2].)
5		No	Go to the next step.
6	Perform the EGR Valve Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD 2.2].) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results.
6		No	Go to the next step.
7	Perform the coolant heater system inspection. (See WATER HEATER SYSTEM OPERATION CHECK [FULL-AUTO AIR CONDITIONER].) (See WATER HEATER SYSTEM OPERATION CHECK [MANUAL AIR CONDITIONER].) Does the coolant heater system operate properly?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning part according to the inspection results.
8	Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR-CD 2.2].) Compare the ECT PID and water temperature gauge on instrument cluster reading. Is the ECT PID value same as water temperature gauge reading?	Yes	Go to the next step.
8		No	Inspect the water temperature gauge. (See INSTRUMENT CLUSTER INSPECTION.) • If there is any malfunction: ― Repair or replace the malfunctioning part according to the inspection results. • If there is no malfunction: ― Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR-CD 2.2].) ― Replace the ECT sensor if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR-CD 2.2].)
9	Cool down the engine. Remove the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD 2.2].) Inspect the thermostat operation. (See THERMOSTAT INSPECTION [MZR-CD 2.2]..) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD 2.2].)
9		No	Thermostat is normal. • Inspect the cylinder 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-CD 2.2].) • 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, reprogram the PCM if a later calibration is available. Retest.