NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [MZR-CD (RF Turbo)]

BME010300103289

18

COOLING SYSTEM CONCERNS-RUNS COLD

DESCRIPTION

• Engine takes excessive period for reaching normal operating temperature.

POSSIBLE CAUSE

• Thermostat malfunction
• Main fan system malfunction
• Additional fan system malfunction
• Coolant heater system malfunction

Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION

1
Is customer complaint "Lack of passenger compartment heat"?
Yes
Inspect the A/C heater system.
No
Go to the next step.
2
Does the engine speed continue at fast idle?
Yes
Go to symptom troubleshooting "NO.7 SLOW RETURN TO IDLE".
No
Go to the next step.
3
Connect the WDS or equivalent to the DLC-2.
Access ECT PID.
Inspect for both ECT PID and the temperature gauge on the instrument cluster readings.
Is ECT PID the same as the temperature gauge reading?
Yes
Go to the next step.
No
If the temperature gauge on the instrument cluster indicates normal range but ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor.
If the temperature gauge on the instrument cluster indicates cold range but ECT PID is normal, inspect the temperature gauge and the heat gauge unit.
4
Inspect the main fan and additional fan operations.
Are both fan operations normal?
Yes
Perform the coolant heater system inspection.
Repair or replace the malfunctioning part according to the coolant heater system operation results.
No
Repair or replace if necessary.
5
Remove the thermostat and inspect operation.
Is the thermostat normal?
Yes
Go to the next step.
No
Replace the thermostat.
6
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)].)