#
NO.20 COOLING SYSTEM CONCERNS-RUNS COLD [MZR-CD (RF Turbo)]

id0103f1821800

20 | COOLING SYSTEM CONCERNS-RUNS COLD
--- | ---
DESCRIPTION | • Engine takes excessive period of time to reach normal operating temperature.
POSSIBLE CAUSE | • Thermostat malfunction • Cooling fan system malfunction • Coolant heater system malfunction

Diagnostic Procedure

STEP | INSPECTION | RESULTS | ACTION
--- | --- | --- | ---
1 | Is the 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 the symptom troubleshooting "NO.9 SLOW RETURN TO IDLE [MZR-CD (RF-Turbo)]".
No | Go to the next step.
3 | Connect the WDS or equivalent to the DLC-2. Access the ECT PID. Inspect the reading for both the ECT PID and the temperature gauge on instrument cluster. Is the 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 a normal range but the ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor. If the temperature gauge on the instrument cluster indicates a cold range but the ECT PID is normal, inspect the temperature gauge and the heat gauge unit.
4 | Remove the thermostat and inspect the operation. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].) (See THERMOSTAT INSPECTION [MZR-CD (RF Turbo)].) Is the thermostat normal? | Yes | Go to the next step.
No | Replace the thermostat.
5 | Perform the cooling fan control system Operation Inspection. (See Cooling Fan Control System Inspection.) Does the cooling fan system work properly? | Yes | Perform the coolant heater system inspection. Repair or replace the malfunctioning part according to coolant heater system operation results.
No | Repair or replace the malfunctioning part according to inspection result.
6 | Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR-CD (RF Turbo)].) • If the malfunction remains, inspect the related Service Information and perform repair or diagnosis. - If the vehicle is repaired, troubleshooting completed. - If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if later calibration is available. Retest.