Mazda Mazda6 Workshop Manual Supplement page 364

NO.18 COOLING SYSTEM CONCERNS-RUNS COLD
18 COOLING SYSTEM CONCERNS-RUNS COLD
• Engine takes excessive period for reaching normal operating temperature.
DESCRIPTION
• Thermostat malfunction
• Cooling fan No.2 system malfunction
POSSIBLE
• Cooling fan No.1 system malfunction
CAUSE
• Coolant heater system malfunction
Diagnostic Procedure
STEP
1 Is customer complaint "Lack of passenger
compartment heat"?
2 Does engine speed continue at fast idle?
3 Connect WDS or equivalent to DLC-2.
Access ECT PID.
Inspect for both ECT PID and temperature
gauge on instrument cluster readings.
Is ECT PID same as temperature gauge
reading?
4 Remove thermostat and inspect operation.
(See E–9 THERMOSTAT REMOVAL/
INSTALLATION)
(See E–10 THERMOSTAT
Is thermostat okay?
5 Inspect cooling fan No.1 and cooling fan No.2
operations.
If both or either fan operate normally, inspect for
following:
• Cooling fan relay No.2 is stuck closed
• Short to GND between cooling fan relay No.2
and PCM terminal 76
• Circuit between cooling fan relay No.2 and
fan motor short to battery supply line
• Cooling fan relay No.1 is stuck closed
• Short to GND between cooling fan relay No.1
and PCM terminal 102
• Circuit between cooling fan relay No.1 and
fan motor short to battery supply line
• Short to GND between A/C switch and PCM
terminal 84
Are all circuits okay?
6 Verify test results.
• If okay, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM. (See
End Of Sie
F2–212
TROUBLESHOOTING
INSPECTION
INSPECTION)
RESULTS
Yes Inspect A/C heater system.
No Go to next step.
Yes Go to symptom troubleshooting "NO.7 SLOW
RETURN TO IDLE".
No Go to next step.
Yes Go to next step.
No If temperature gauge on instrument cluster indicates
normal range but ECT PID is not same as temperature
gauge reading, inspect ECT sensor.
If temperature gauge on instrument cluster indicates
cold range but ECT PID is normal, inspect
temperature gauge and heat gauge unit.
Yes Go to next step.
No Replace thermostat.
Yes Perform coolant heater system inspection.
Repair or replace malfunctioning part according to
coolant heater system operation results.
No Repair or replace as necessary.
F2–64 PCM REMOVAL/INSTALLATION)
A6E408018881220
ACTION