NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [L3 Turbo]

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

STEP	INSPECTION	RESULTS	ACTION
1	Is a customer complaint “Lack of passenger compartment heat” only?	Yes	Inspect the A/C heater system. • If there is any malfunction: ― Repair or replace the malfunctioning part according to the inspection results.
No	Go to the next step.
2	Does the engine speed continue at fast idle?	Yes	Perform the symptom troubleshooting “NO.9 FAST IDLE/RUNS ON”. (See NO.9 FAST IDLE/RUNS ON [L3 Turbo].)
No	Go to the next step.
3	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the cooling fan system operate properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
4	Cool down the engine. Remove the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [L3 Turbo].) Inspect the thermostat. (See THERMOSTAT INSPECTION [L3 Turbo].) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [L3 Turbo].)
No	Reinstall the thermostat, then go to the next step. (See THERMOSTAT REMOVAL/INSTALLATION [L3 Turbo].)
5	Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].) Inspect for both ECT PID and temperature gauge readings. Does the ECT PID value accord with the engine coolant temperature indicator readings?	Yes	The engine coolant temperature and thermostat are normal. • Inspect the engine block for leakage or blockage. • Repair or replace the malfunctioning part according to the inspection results.
No	If the low engine coolant temperature indicator light on the instrument cluster indicates turned off but the ECT PID value is not the same as the low engine coolant temperature indicator light condition: • Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L3 Turbo].) • Replace the ECT sensor if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) If the low engine coolant temperature indicator light indication on the instrument cluster illuminates but the ECT PID value is normal: • Inspect the instrument cluster. (See INSTRUMENT CLUSTER INSPECTION.) • Replace the instrument cluster if necessary. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)
6	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If a malfunction remains, inspect the related Service Information and perform the repair or diagnosis. ― If the vehicle is repaired, troubleshooting is completed. ― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.

STEP

INSPECTION

RESULTS

ACTION

Is a customer complaint “Lack of passenger compartment heat” only?

Yes

Inspect the A/C heater system.

• If there is any malfunction:

― Repair or replace the malfunctioning part according to the inspection results.

Go to the next step.

Does the engine speed continue at fast idle?

Yes

Perform the symptom troubleshooting “NO.9 FAST IDLE/RUNS ON”.

(See NO.9 FAST IDLE/RUNS ON [L3 Turbo].)

Go to the next step.

Perform the Cooling Fan Control System Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the cooling fan system operate properly?

Yes

Go to the next step.

Repair or replace the malfunctioning part according to the inspection results.

Cool down the engine.

Remove the thermostat.

(See THERMOSTAT REMOVAL/INSTALLATION [L3 Turbo].)

Inspect the thermostat.

(See THERMOSTAT INSPECTION [L3 Turbo].)

Is there any malfunction?

Yes

Replace the thermostat.

(See THERMOSTAT REMOVAL/INSTALLATION [L3 Turbo].)

Reinstall the thermostat, then go to the next step.

(See THERMOSTAT REMOVAL/INSTALLATION [L3 Turbo].)

Access the ECT PID using the M-MDS.

(See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].)

Inspect for both ECT PID and temperature gauge readings.

Does the ECT PID value accord with the engine coolant temperature indicator readings?

Yes

The engine coolant temperature and thermostat are normal.

• Inspect the engine block for leakage or blockage.

• Repair or replace the malfunctioning part according to the inspection results.

If the low engine coolant temperature indicator light on the instrument cluster indicates turned off but the ECT PID value is not the same as the low engine coolant temperature indicator light condition:

• Inspect the ECT sensor.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L3 Turbo].)

• Replace the ECT sensor if necessary.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [L3 Turbo].)

If the low engine coolant temperature indicator light indication on the instrument cluster illuminates but the ECT PID value is normal:

• Inspect the instrument cluster.

(See INSTRUMENT CLUSTER INSPECTION.)

• Replace the instrument cluster if necessary.

(See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)

Verify test results.

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

• If a malfunction remains, inspect the related Service Information and perform the repair or diagnosis.

― If the vehicle is repaired, troubleshooting is completed.

― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.