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 .)
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 .) (See THERMOSTAT INSPECTION .) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION .)
3		No	Go to the next step.
4	Inspect the cooling fan control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION .) 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 .) 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 .) Replace the ECT sensor, if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .) 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 .) If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform 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.