Diagnostic Procedure

DIAGNOSTIC PROCEDURE CHART

STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: Engine coolant level Coolant leakage Water and anti-freeze mixture Radiator condition Collapsed or restricted radiator hoses Radiator pressure cap Overflow system Fan rotational direction Fuses Are all items normal?	Yes	Go to the next step.
1		No	Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
2	Turn the ignition switch to the ON position (Engine off). Retrieve any PCM DTCs using the M-MDS. See ON-BOARD DIAGNOSTIC TEST article. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE article.)
2		No	No DTC is displayed: Go to the next step.
3	Start the engine and idle it. Turn the A/C switch on and set blower fan to any speed by switching the control panel. Does the A/C compressor engage/disengage according to control panel switching?	Yes	Go to the next step
3		No	If the A/C compressor is not engaged always: Go to the symptom troubleshooting, see NO. 23 A/C DOES NOT WORK SUFFICIENTLY . If the A/C compressor is engaged always: Go to the symptom troubleshooting, see NO. 24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY .
4	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.
4		No	Repair or replace the malfunctioning part according to the inspection results.
5	Inspect the drive belt. See DRIVE BELT INSPECTION article. Is the drive belt normal	Yes	Go to the next step.
5		No	Replace the drive belt. See DRIVE BELT REMOVAL/INSTALLATION article.
6	Is there leakage around the heater unit in passenger compartment?	Yes	Inspect and service heater for leakage. Repair or replace the malfunctioning part according to the inspection results.
6		No	Go to the next step.
7	Is there leakage at the coolant hoses and/or radiator?	Yes	Repair or replace the malfunctioning part according to the inspection results.
7	Is there leakage at the coolant hoses and/or radiator?	No	Go to the next step.
8	Access and monitor the PCM PID ECT using the M-MDS. See ON-BOARD DIAGNOSTIC TEST article. Compare the ECT PID and water temperature gauge on instrument cluster reading. Is the ECT PID reading the same as water temperature gauge reading?	Yes	Go to the next step
8		No	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.
9	Cool down the engine. Remove thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION article.) (See THERMOSTAT INSPECTION article.) Is thermostat normal?	Yes	The engine coolant temperature and thermostat are normal, inspect engine block for leakage or blockage. Repair or replace the malfunctioning part according to the inspection results.
9		No	Replace the thermostat. See THERMOSTAT REMOVAL/INSTALLATION article.
10	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 the PCM. (See PCM REMOVAL/INSTALLATION article.)