Mazda CX-9 Grand Touring. Manual - part 341

NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZI-3.7]

NO.17 COOLING SYSTEM CONCERNS-OVERHEATING (MZI-3.7) DETECTION CONDITIONS
AND POSSIBLE CAUSES

DIAGNOSTIC PROCEDURE

NO.17 COOLING SYSTEM CONCERNS-OVERHEATING (MZI-3.7) DIAGNOSTIC PROCEDURE



If malfunction remains, inspect related Service Bulletins and/or On-line Repair
Information and perform repair or diagnosis.



If vehicle is repaired, troubleshooting completed.



If vehicle is not repaired or additional diagnostic information is not available,
replace the PCM.

(See PCM REMOVAL/INSTALLATION [MZI-3.7] .)

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



A/C system operation is improper



Improper water/anti-freeze mixture



Fans reverse rotation



Poor radiator condition



Thermostat malfunction



Radiator hoses damage



Improper or damaged radiator cap



Cooling fan is inoperative.



Coolant overflow system malfunction



Improper tension of drive belt



Drive belt damage

STEP

INSPECTION

RESULTS

ACTION

Inspect the following:



Engine coolant level



Coolant leakage



Water and anti-freeze mixture



Radiator condition

Yes

Go to the next step.

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:05 AM

Page 70



Collapsed or restricted radiator
hoses



Radiator pressure cap



Overflow system



Fan rotational direction



Fuses

Are all items normal?

Service if necessary.

Repeat Step 1.

Connect the M-MDS to the DLC-2.
Turn the ignition switch to the ON
position (Engine off).
Retrieve any DTCs.
Are there any DTCs displayed?

Yes

DTC is displayed:
Go to the appropriate DTC inspection.
(See DTC TABLE [MZI-3.7] .)

No DTC is displayed:

Go to the next step.

Start the engine and idle it.
Turn the A/C switch on and set blower fan
to any speed.
Does the A/C compressor engage?

Yes

Go to Step 5.

Inspect for the following and repair or

replace if necessary:



Refrigerant charging amount



Open circuit in wiring harness

between A/C relay and PCM

terminal 1N



Seized A/C magnetic clutch



A/C magnetic clutch malfunction

If all items are normal, go to the next step.

Connect the M-MDS to the DLC-2.
Access AC_REQ PID.
Start the engine and idle it.
Turn the A/C switch and fan switch on.
Does AC_REQ PID read on?

Yes

Go to the next step.

Inspect the following:



Refrigerant pressure switch

operation



The A/C switch is stuck open.



Open or short circuit between

refrigerant pressure switch and PCM

terminal 1R



Open circuit of blower motor fan

switch and resistor (if blower motor

does not operate)



The evaporator temperature sensor

and A/C amplifier

Inspect cooling fan control system
operation.

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:05 AM

Page 71

NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [MZI-3.7]

NO.18 COOLING SYSTEM CONCERNS-RUNS COLD (MZI-3.7) DETECTION CONDITIONS AND
POSSIBLE CAUSES

(See ENGINE CONTROL SYSTEM
OPERATION INSPECTION [MZI-
3.7].)
Does the cooling fan control system
function properly?

Yes

Go to the next step.

Repair or replace the malfunctioning part.

Is the drive belt normal?

Yes

Go to the next step.

Replace the drive belt.

Is there leakage around the heater unit in
passenger compartment?

Yes

Inspect and service heater for leakage.

Go to the next step.

Is there leakage at the coolant hoses and/or
radiator?

Yes

Replace the malfunctioning part.

Go to the next step.

Cool down the engine.
Remove thermostat and inspect operation.
(See THERMOSTAT
REMOVAL/INSTALLATION [MZI-
3.7] .)
(See THERMOSTAT INSPECTION
[MZI-3.7] .)
Is thermostat normal?

Yes

The engine coolant temperature and
thermostat are normal, inspect engine
block for leakage or blockage.

Access ECT PID.

Inspect for both ECT PID and temperature

gauge readings.

If temperature gauge on instrument cluster

indicates normal range but ECT PID is not

same as temperature gauge reading, inspect

CHT sensor.

If temperature gauge on instrument cluster

indicates overheating but ECT PID is

normal, inspect temperature gauge and heat

gauge unit.



Verify test results.



If normal, return to diagnostic index to service any additional symptoms.

(See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].)



If malfunction remains, inspect related Service Bulletins and/or On-line Repair
Information and perform repair or diagnosis.



If vehicle is repaired, troubleshooting completed.



If vehicle is not repaired or additional diagnostic information is not available,
replace the PCM.

(See PCM REMOVAL/INSTALLATION [MZI-3.7] .)

COOLING SYSTEM CONCERNS-RUNS COLD

DESCRIPTION

Engine takes excessive time to reach normal operating temperature.

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:05 AM

Page 72

DIAGNOSTIC PROCEDURE

NO.18 COOLING SYSTEM CONCERNS-RUNS COLD (MZI-3.7) DIAGNOSTIC PROCEDURE

POSSIBLE CAUSE



Thermostat malfunction



Cooling fan system malfunction

STEP

INSPECTION

RESULTS

ACTION

Is customer complaint "Lack of passenger
compartment heat" only?

Yes

Inspect A/C and heater system.

Go to the next step.

Does the engine speed continue at fast
idle?

Yes

Go to symptom troubleshooting "No.9 Fast
idle/runs on".
(See NO.9 FAST IDLE/RUNS ON [MZI-
3.7].)

Go to the next step.

Remove the thermostat and inspect
operation.
(See THERMOSTAT
REMOVAL/INSTALLATION [MZI-
3.7] .)
(See THERMOSTAT INSPECTION
[MZI-3.7] .)
Is thermostat normal?

Yes

Go to the next step.

Replace the thermostat.

Inspect cooling fan control system
operation.
(See ENGINE CONTROL SYSTEM
OPERATION INSPECTION [MZI-
3.7].)
Does the cooling fan control system
function properly?

Yes

Access ECT PID.
Inspect for both ECT PID and temperature
gauge on instrument cluster readings.
If the temperature gauge on the instrument
cluster indicates normal range but ECT PID
is not the same as temperature gauge
reading, inspect the CHT sensor.
If the temperature gauge on the instrument
cluster indicates cold range but ECT PID is
normal, inspect the temperature gauge and
heat gauge unit.

Repair or replace the malfunctioning part.



Verify test results.



If normal, return to diagnostic index to service any additional symptoms.

(See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].)



If malfunction remains, inspect related Service Bulletins and/or On-line Repair
Information and perform repair or diagnosis.



If vehicle is repaired, troubleshooting completed.



If vehicle is not repaired or additional diagnostic information is not available,
replace PCM.

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:05 AM

Page 73

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