NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [MZR 1.5, MZR 1.6]

id0103e0802400

18

COOLING SYSTEM CONCERNS—RUNS COLD

DESCRIPTION

•  The engine does not reach normal operating temperature.

POSSIBLE CAUSE

•  Condenser fan system malfunction

•  Cooling fan system malfunction

•  Thermostat malfunction

•  ECT sensor malfunction

•  PCM malfunction

18	COOLING SYSTEM CONCERNS—RUNS COLD
DESCRIPTION	• The engine does not reach normal operating temperature.
POSSIBLE CAUSE	• Condenser fan system malfunction • Cooling fan system malfunction • Thermostat malfunction • ECT sensor malfunction • PCM malfunction

Diagnostic procedure

STEP	INSPECTION	ACTION
1	Is the customer complaint “Lack of passenger compartment heat” only?	Yes	Inspect the A/C and heater system. Repair or replace the malfunctioning part according to the inspection results.
1		No	Go to the next step.
2	Does the engine speed continue at fast idle?	Yes	Go to the symptom troubleshooting “NO.9 FAST IDLE/RUNS ON”. (See NO.9 FAST IDLE/RUNS ON [MZR 1.5, MZR 1.6].)
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Remove the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].) Inspect the thermostat operation. (See THERMOSTAT INSPECTION [MZR 1.5, MZR 1.6].) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)
3		No	Go to the next step.
4	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.5, MZR 1.6].) Does the cooling fan control system work properly?	Yes	Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 1.5, MZR 1.6].) Inspect for both the ECT PID and the low engine coolant temperature indicator light on instrument cluster condition. • If the low engine coolant temperature indicator light on the instrument cluster turns off but the ECT PID is not same as the low engine coolant temperature indicator light condition: ― Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR 1.5, MZR 1.6].) ― Replace the ECT sensor, if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].) • If the low engine coolant temperature indicator light on the instrument cluster indicates overheating but the ECT PID is normal: ― Inspect the instrument cluster. (See INSTRUMENT CLUSTER INSPECTION.) • Repair or replace the malfunctioning part according to the inspection results.
4		No	Repair or replace the malfunctioning part according to the inspection results.
5	Verify the test results. • If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 1.5, MZR 1.6].) • If malfunction remains, inspect related Service information perform repair or diagnosis. ― If vehicle repaired, troubleshooting completed. ― If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)