NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [L5]

NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [L5]SM2444479

NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [L5]

id0103a8802400

18	COOLING SYSTEM CONCERNS—RUNS COLD
DESCRIPTION	• Engine does not reach normal operating temperature.
POSSIBLE CAUSE	• A/C and heater system malfunction • Thermostat malfunction • Improper operation of cooling fan control system

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	Is the customer complaint "Lack of passenger compartment heat" only?	Yes	Inspect 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 [L5].)
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Cool down the engine. Remove the thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION [L5].) (See THERMOSTAT INSPECTION [L5].) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [L5].)
3		No	Reinstall the thermostat, then go to the next step. (See THERMOSTAT REMOVAL/INSTALLATION [L5].)
4	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L5].) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results.
4		No	Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [L5].) Inspect for both ECT PID and temperature gauge readings. • If the temperature gauge on instrument cluster indicates normal but the ECT PID is not same as temperature gauge reading: ― Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L5].) ― Replace the ECT sensor, if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [L5].) • If the temperature gauge on instrument cluster indicates overheating but the ECT PID is normal: ― Inspect the instrument cluster. (See INSTRUMENT CLUSTER INSPECTION.) ― Replace the instrument cluster, if necessary. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)
5	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [L5].) • If the 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.