NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [LF, L5]

id010397802300

17

COOLING SYSTEM CONCERNS—OVERHEATING

DESCRIPTION

•  The engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

•  Improper coolant level

•  Blown fuses

•  Coolant leakage

•  Excessive A/C system pressure

•  A/C system operation is improper

―  Climate control unit malfunction (A/C switch malfunction or climate control unit does not determine A/C request or transmit the A/C request signal)

―  Instrument cluster malfunction (does not receive A/C request signal from climate control unit or transmit it to PCM)

―  Communication error between PCM and instrument cluster

―  Communication error between instrument cluster and climate control unit

•  Improper water/anti-freeze mixture

•  Fans reverse rotation

•  Poor radiator condition

•  Thermostat malfunction

•  Radiator hoses damage

•  Improper or damaged radiator cap

•  Cooling fan is inoperative

•  Coolant overflow system malfunction

•  Improper tension of drive belt

•  Drive belt damage

•  PCM malfunction

17	COOLING SYSTEM CONCERNS—OVERHEATING
DESCRIPTION	• The engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Improper coolant level • Blown fuses • Coolant leakage • Excessive A/C system pressure • A/C system operation is improper ― Climate control unit malfunction (A/C switch malfunction or climate control unit does not determine A/C request or transmit the A/C request signal) ― Instrument cluster malfunction (does not receive A/C request signal from climate control unit or transmit it to PCM) ― Communication error between PCM and instrument cluster ― Communication error between instrument cluster and climate control unit • Improper water/anti-freeze mixture • Fans reverse rotation • Poor radiator condition • Thermostat malfunction • Radiator hoses damage • Improper or damaged radiator cap • Cooling fan is inoperative • Coolant overflow system malfunction • Improper tension of drive belt • Drive belt damage • PCM malfunction

Diagnostic procedure

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	Connect the M-MDS to the DLC-2. Switch the ignition to ON (engine off). Retrieve the PCM, instrument cluster, multi information display and climate control unit DTCs. (See ON-BOARD DIAGNOSTIC TEST [LF, L5].) (See DTC INSPECTION [INSTRUMENT CLUSTER].) (See DTC INSPECTION [INFORMATION DISPLAY/MULTI INFORMATION DISPLAY].) (See DTC DISPLAY [FULL-AUTO AIR CONDITIONER].) Are any DTCs present?	Yes	Go to the appropriate DTC inspection. (See DTC TABLE [LF, L5].) (See DTC TABLE [INSTRUMENT CLUSTER].) (See DTC TABLE [INFORMATION DISPLAY/MULTI INFORMATION DISPLAY].) (See DTC TABLE [FULL-AUTO AIR CONDITIONER].)
2		No	Go to the next step.
3	Start the engine and idle it. Turn the A/C switch on and set the blower fan to any speed. Does the A/C compressor engage?	Yes	Go to Step 8.
3		No	Inspect the following: • Refrigerant charging amount • Open circuit in the wiring harness between the A/C relay and PCM terminal 1I • Seized A/C magnetic clutch • A/C magnetic clutch malfunction ― If there is a malfunction: • Repair or replace the malfunctioning part according to the inspection results. ― If all items are normal: • Go to the next step.
4	Connect the M-MDS to the DLC-2. Access the PCM PID AC_REQ using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [LF, L5].) Start the engine and idle it. Monitor the AC_REQ PID while turning on and off the air conditioner by switching the control panel. Does the PID change according to air control panel switching? (See PCM INSPECTION [LF, L5].)	Yes	Go to Step 8.
4		No	Go to the next step.
5	Verify the multi information display indication of A/C system while turning on and off the air conditioner by switching the control panel. Does the multi information display indicate properly?	Yes	Replace the instrument cluster. (Instrument cluster does not receive the A/C request signal from climate control unit or transmit to PCM.) (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)
5		No	Go to the next step.
6	Inspect the multi information display. (See MULTI INFORMATION DISPLAY INSPECTION.) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results, then go to the next step.
6		No	Go to the next step.
7	Connect the M-MDS to the DLC-2. Access climate control unit PIDs EVAP_TEMP and AC_PRES using the M-MDS. (See PID/DATA MONITOR DISPLAY [FULL-AUTO AIR CONDITIONER].) Monitor the EVAP_TEMP and AC_PRES PIDs while turning on and off the air conditioner by switching the control panel. Are the PIDs normal? (See PID/DATA MONITOR TABLE [FULL-AUTO AIR CONDITIONER].)	Yes	Replace the climate control unit. (A/C switch malfunction or climate control unit does not determine A/C request or transmit to the A/C request signal.) (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
7		No	Repair or replace the malfunctioning part according to the inspection results.
8	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [LF, L5].) Does the cooling fan control system function properly?	Yes	Go to the next step.
8		No	Repair or replace the malfunctioning part according to the inspection results.
9	Inspect the drive belt. (See DRIVE BELT INSPECTION [LF, L5].) Is there any malfunction?	Yes	Replace the drive belt. (See DRIVE BELT REMOVAL/INSTALLATION [LF, L5].)
9		No	Go to the next step.
10	Is there leakage around the heater unit in the passenger compartment?	Yes	Inspect and service heater for leakage.
10		No	Go to the next step.
11	Is there leakage at the coolant hoses and/or radiator?	Yes	Repair or replace the malfunctioning part according to the inspection results.
11	Is there leakage at the coolant hoses and/or radiator?	No	Go to the next step.
12	Cool down the engine. Remove thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [LF, L5].) Inspect the thermostat operation. (See THERMOSTAT INSPECTION [LF, L5].) Is there any malfunction?	Yes	Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [LF, L5].) Inspect for both the ECT PID and the low engine coolant temperature indicator light condition. • If the low engine coolant temperature indicator light on the instrument cluster turns off but the ECT PID is not same as the low engine coolant temperature indicator light condition: ― Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [LF, L5].) ― Replace the ECT sensor, if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [LF, L5].) • If the low engine coolant temperature indicator light on the 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.)
12		No	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.
13	• Verify the test results. ― If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [LF, L5].) ― If a malfunction remains, inspect the related Service Information perform repair or diagnosis. • If the vehicle repaired, troubleshooting is completed. • If the vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [LF, L5].)