NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR-CD (RF Turbo)]


17	COOLING SYSTEM CONCERNS-OVERHEATING
DESCRIPTION	• Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Improper coolant level • Blown fuses • Coolant leakage • Excessive A/C system pressure • Improper water/anti-freeze mixture • Fans reverse rotation • Poor radiator condition • Thermostat malfunction • Radiator hoses damage • Condenser fan is inoperative. • Improper or damaged radiator cap • Cooling fan is inoperative. • Coolant overflow system malfunction • Improper tension of drive belt • Drive belt damage • Fan control module malfunction


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 self-test function using the WDS or equivalent. Turn the engine switch to the ON position. Retrieve any DTC. Is DTC displayed?	Yes	DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [MZR-CD (RF Turbo)].) Communication error message is displayed: Inspect for the following: • Open circuit between PCM control relay and PCM terminal 53 or 79 • Open circuit PCM control relay and PCM terminal 69 • PCM control relay stuck open • Open or poor GND circuit (PCM terminal 65, 85, 103 or 104) • Poor connection vehicle body GND
2		No	No DTC is displayed: Go to the next step.
3	Note • The following test should be performed on the vehicles with the A/C system. Go to the next step for the vehicles without the A/C system 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 symptom troubleshooting "NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY". (See NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD (RF Turbo)].)
4	Start the engine and run it at idle speed. Turn the A/C switch on if equipped. Do the compressor fan and/or the cooling fan operate?	Yes	Go to the next step.
4		No	Cooling fan motor does not operate: • Inspect for the following: - Cooling fan motor malfunction - Cooling fan motor GND open - Open circuit between cooling fan motor and fan control module Condenser fan motor does not operate: • Inspect for the following: - Condenser fan motor malfunction - Condenser fan motor GND open - Open circuit between condenser fan motor and fan control module Both cooling fan and condenser fan do not operate: • Inspect for the following: - Fan control module malfunction - Fan control module GND open - Open circuit between fan control module and cooling fan relay
5	Is the drive belt normal?	Yes	Go to the next step.
5	Is the drive belt normal?	No	Replace the drive belt.
6	Perform the EGR system inspection. Is the EGR system normal?	Yes	Go to the next step.
6		No	Repair or replace the malfunctioning part according to the EGR system operation results.
7	Inspect the EGR water cooler for the following: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is the EGR water cooler normal?	Yes	Go to the next step.
7		No	Service if necessary.
8	Perform the coolant heater system inspection. (See THERMOSTAT INSPECTION.) Is the coolant heater system normal?	Yes	Go to the next step.
8		No	Repair or replace the malfunctioning part according to the coolant heater system operation results.
9	Cool down the engine. Remove the thermostat and inspect operation. Is the thermostat normal?	Yes	The thermostat is normal. Inspect the cylinder block for leakage or blockage.
9		No	Replace the thermostat.
10	Verify test results. • If normal, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)