Diagnostic Procedure

DIAGNOSTIC PROCEDURE CHART

STEP	INSPECTION	RESULTS	ACTION
1	Is 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 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	Inspect cooling fan control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION .) Does the cooling fan control system function properly?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning part according to the inspection results.
4	Cool down the engine. Remove the thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION article.) (See THERMOSTAT INSPECTION article.) Is thermostat normal?	Yes	Inspect the water temperature gauge. See INSTRUMENT CLUSTER INSPECTION article. Repair or replace the malfunctioning part according to the inspection results. If the water temperature gauge reading is normal, inspect the CHT sensor. See CYLINDER HEAD TEMPERATURE (CHT) SENSOR INSPECTION article. Repair or replace the malfunctioning part according to the inspection results.
4		No	Replace the thermostat. See THERMOSTAT REMOVAL/INSTALLATION article.
5	Verify test results. If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX .) If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, replace PCM. (See PCM REMOVAL/INSTALLATION article.)