NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [L8, LF]

17	COOLING SYSTEM CONCERNS—OVERHEATING
DESCRIPTION	• Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Collapsed or restricted radiator hoses • Coolant leakage • Improper coolant level • Blown fuses • Coolant overflow system malfunction • Poor radiator condition • Improper or damaged radiator cap • Improper water/anti‐freeze mixture • Improper operation of A/C system • Improper operation of cooling fan control system • Drive belt damage • Leakage from heater unit in passenger compartment • Leakage from coolant hose and/or radiator • Thermostat malfunction • ECT sensor malfunction • Instrument cluster malfunction • PCM malfunction

COOLING SYSTEM CONCERNS—OVERHEATING

DESCRIPTION

• Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

• Collapsed or restricted radiator hoses

• Coolant leakage

• Improper coolant level

• Blown fuses

• Coolant overflow system malfunction

• Poor radiator condition

• Improper or damaged radiator cap

• Improper water/anti‐freeze mixture

• Improper operation of A/C system

• Improper operation of cooling fan control system

• Drive belt damage

• Leakage from heater unit in passenger compartment

• Leakage from coolant hose and/or radiator

• Thermostat malfunction

• ECT sensor malfunction

• Instrument cluster malfunction

• PCM malfunction

STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: • Collapsed or restricted radiator hoses • Coolant leakage • Engine coolant level • Fan rotational direction • Fuses • Overflow system • Radiator condition • Radiator pressure cap • Water and anti‐freeze mixture Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
No	Go to the next step.
2	Connect the M-MDS to the DLC-2. Perform the KOEO/KOER self test and the DTC Reading Procedure. (See KOEO/KOER SELF TEST [L8, LF].) (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) Are any DTCs present?	Yes	Go to the appropriate DTC inspection. (See DTC TABLE [L8, LF].)
No	Go to the next step.
3	Note • Following test is for vehicle with A/C system. If the A/C system is not equipped, go to the next step. Start the engine and idle it. Turn the A/C switch on. Does the A/C compressor engage?	Yes	Go to Step 5.
No	Inspect the following: • A/C magnetic clutch malfunction • Open circuit in wiring harness between A/C relay and PCM terminal 1I • Refrigerant charging amount • Seized A/C magnetic clutch 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. Perform the PID/DATA Monitor and Record Procedure and access the AC_REQ PID. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) Start the engine and idle it. Turn the A/C switch on. Does the AC_REQ PID read On?	Yes	Go to the next step.
No	Inspect the following: • A/C switch is stuck open • Evaporator temperature sensor and A/C amplifier • Open or short circuit between refrigerant pressure switch and PCM terminal 1AU • Open circuit of blower motor fan switch and resistor (if blower motor does not operate) • Refrigerant pressure switch operation Repair or replace the malfunctioning part according to the inspection results.
5	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF].) Does the cooling fan control system function properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
6	Inspect the drive belt. (See DRIVE BELT INSPECTION [L8, LF].) Is there any malfunction?	Yes	Replace the drive belt. (See DRIVE BELT REPLACEMENT [L8, LF].)
No	Go to the next step.
7	Visually inspect the heater unit in passenger compartment. Is there any leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results.
No	Go to the next step.
8	Visually inspect the coolant hoses and/or radiator. Is there any leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results.
No	Go to the next step.
9	Cool down the engine. Remove thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION [L8, LF].) (See THERMOSTAT INSPECTION [L8, LF].) Is there any malfunction?	Yes	Go to the next step.
No	ECT sensor and thermostat are normal. • Inspect the engine block for leakage or blockage. • Repair or replace the malfunctioning part according to the inspection results.
10	Connect the M-MDS to the DLC-2. Perform the PID/DATA Monitor and Record Procedure and access the ECT PID. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) Inspect for both ECT PID and temperature gauge on instrument cluster readings. Is the ECT PID value same as temperature gauge on instrument cluster?	Yes	Go to the next step.
No	Access the ECT PID. Inspect 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 indicates turned off but the ECT PID is not the same as the low engine coolant temperature indicator light condition: ― Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L8, LF].) • If the low engine coolant temperature indicator light indication on the instrument cluster illuminates but the ECT PID is normal: ― Inspect the instrument cluster. (See INSTRUMENT CLUSTER INSPECTION.) Repair or replace the malfunctioning part according to the inspection results.
11	Verify test results. • If normal, return to diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [L8, LF].) • If malfunction remains, inspect related Service information perform repair or diagnosis. ― If vehicle repaired, troubleshooting completed. ― If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF].)

STEP

INSPECTION

RESULTS

ACTION

Inspect the following:

• Collapsed or restricted radiator hoses

• Coolant leakage

• Engine coolant level

• Fan rotational direction

• Fuses

• Overflow system

• Radiator condition

• Radiator pressure cap

• Water and anti‐freeze mixture

Is there any malfunction?

Yes

Repair or replace the malfunctioning part according to the inspection results.

Repeat Step 1.

Go to the next step.

Connect the M-MDS to the DLC-2.

Perform the KOEO/KOER self test and the DTC Reading Procedure.

(See KOEO/KOER SELF TEST [L8, LF].)

(See ON-BOARD DIAGNOSTIC TEST [L8, LF].)

Are any DTCs present?

Yes

Go to the appropriate DTC inspection.

(See DTC TABLE [L8, LF].)

Go to the next step.

Note

• Following test is for vehicle with A/C system. If the A/C system is not equipped, go to the next step.

Start the engine and idle it.

Turn the A/C switch on.

Does the A/C compressor engage?

Yes

Go to Step 5.

Inspect the following:

• A/C magnetic clutch malfunction

• Open circuit in wiring harness between A/C relay and PCM terminal 1I

• Refrigerant charging amount

• Seized A/C magnetic clutch

Repair or replace the malfunctioning part according to the inspection results.

If all items are normal, go to the next step.

Connect the M-MDS to the DLC-2.

Perform the PID/DATA Monitor and Record Procedure and access the AC_REQ PID.

(See ON-BOARD DIAGNOSTIC TEST [L8, LF].)

Start the engine and idle it.

Turn the A/C switch on.

Does the AC_REQ PID read On?

Yes

Go to the next step.

Inspect the following:

• A/C switch is stuck open

• Evaporator temperature sensor and A/C amplifier

• Open or short circuit between refrigerant pressure switch and PCM terminal 1AU

• Open circuit of blower motor fan switch and resistor (if blower motor does not operate)

• Refrigerant pressure switch operation

Repair or replace the malfunctioning part according to the inspection results.

Perform the Cooling Fan Control System Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF].)

Does the cooling fan control system function properly?

Yes

Go to the next step.

Repair or replace the malfunctioning part according to the inspection results.

Inspect the drive belt.

(See DRIVE BELT INSPECTION [L8, LF].)

Is there any malfunction?

Yes

Replace the drive belt.

(See DRIVE BELT REPLACEMENT [L8, LF].)

Go to the next step.

Visually inspect the heater unit in passenger compartment.

Is there any leakage?

Yes

Repair or replace the malfunctioning part according to the inspection results.

Go to the next step.

Visually inspect the coolant hoses and/or radiator.

Is there any leakage?

Yes

Repair or replace the malfunctioning part according to the inspection results.

Go to the next step.

Cool down the engine.

Remove thermostat and inspect operation.

(See THERMOSTAT REMOVAL/INSTALLATION [L8, LF].)

(See THERMOSTAT INSPECTION [L8, LF].)

Is there any malfunction?

Yes

Go to the next step.

ECT sensor and thermostat are normal.

• Inspect the engine block for leakage or blockage.

• Repair or replace the malfunctioning part according to the inspection results.

Connect the M-MDS to the DLC-2.

Perform the PID/DATA Monitor and Record Procedure and access the ECT PID.

(See ON-BOARD DIAGNOSTIC TEST [L8, LF].)

Inspect for both ECT PID and temperature gauge on instrument cluster readings.

Is the ECT PID value same as temperature gauge on instrument cluster?

Yes

Go to the next step.

Access the ECT PID.

Inspect 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 indicates turned off but the ECT PID is not the same as the low engine coolant temperature indicator light condition:

― Inspect the ECT sensor.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L8, LF].)

• If the low engine coolant temperature indicator light indication on the instrument cluster illuminates but the ECT PID is normal:

― Inspect the instrument cluster.

(See INSTRUMENT CLUSTER INSPECTION.)

Repair or replace the malfunctioning part according to the inspection results.

Verify test results.

• If normal, return to diagnostic index to service any additional symptoms.

(See ENGINE SYMPTOM TROUBLESHOOTING [L8, LF].)

• If malfunction remains, inspect related Service information perform repair or diagnosis.

― If vehicle repaired, troubleshooting completed.

― If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF].)