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	• Main fan malfunction • Additional 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 • EGR water cooler malfunction • Coolant heater system malfunction


STEP	INSPECTION	RESULTS	ACTION
1	Inspect 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 okay?	Yes	Go to next step.
1		No	Service as necessary. Repeat Step 1.
2	Perform self-test function using WDS or equivalent. Turn engine switch to ON. Retrieve any DTC. Is DTC displayed?	Yes	DTC is displayed: Go to appropriate DTC test. Communication error message is displayed: Inspect for 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 next step.
3	Note • The following test should be performed on the vehicles with A/C system. Go to next step for vehicles without A/C system Start engine and run it at idle speed. Turn A/C switch off. Does A/C compressor disengaged?	Yes	Go to next step.
3		No	Go to symptom troubleshooting "NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY".
4	Start engine and run it at idle speed. Turn A/C switch on if equipped. Do compressor fan and/or cooling fan operate?	Yes	Go to next step.
4		No	Additional fan does not operate: Inspect for following: • Additional fan relay is stuck open • Additional fan motor malfunction • Additional fan motor GND open • Open circuit between additional fan motor and relay • Open circuit between additional fan relay and PCM terminal 102 • Open battery power circuit of condenser fan relay Main fan motor does not operate: Inspect for following: • Main fan relay is stuck open • Main fan motor malfunction • Main fan motor GND open • Open circuit between main fan motor and relay • Open circuit between main fan relay and PCM terminal 76 • Open battery power circuit of main fan relay
5	Is drive belt okay?	Yes	Go to next step.
5	Is drive belt okay?	No	Replace drive belt.
6	Perform EGR system inspection. Is EGR system okay?	Yes	Go to next step.
6	Perform EGR system inspection. Is EGR system okay?	No	Repair or replace malfunctioning part according to EGR system operation results.
7	Inspect EGR water cooler for followings: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is EGR water cooler okay?	Yes	Go to next step.
7		No	Service as necessary.
8	Perform coolant heater system inspection. (See THERMOSTAT INSPECTION.) Is coolant heater system okay?	Yes	Go to next step.
8		No	Repair or replace malfunctioning part according to coolant heater system operation results.
9	Cool down engine. Remove thermostat and inspect operation. Is thermostat okay?	Yes	Thermostat is okay. Inspect cylinder block for leakage or blockage.
9		No	Replace thermostat.
10	Verify test results. • If okay, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)