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NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [SKYACTIV-G 2.0]

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2016 – MX-5 – Engine

NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [SKYACTIV-G 2.0]

17

COOLING SYSTEM CONCERNS-OVERHEATING

DESCRIPTION

  • Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

  • Engine heat generation amount is excessive

    • Engine speed is high and remains high for continuous long periods

  • PCM DTC is stored

  • Improper operation of A/C system

  • Insufficient air blow volume

    • Cooling fan inoperative

    • Fan rotation speed decreases (such as generator malfunction) due to battery voltage decrease

  • Cooling system cap malfunction

  • Cooling fan motor assembly malfunction

  • Cooling fan motor connector malfunction

  • Improper indication of low engine coolant temperature indicator light and/or high engine coolant temperature warning light

    • ECT sensor No.1 malfunction

    • Instrument cluster malfunction

  • Blown fuse

  • Engine coolant system malfunction

    • Engine coolant performance deterioration

    • Coolant leakage (engine internal, external)

    • Improper water/anti-freeze mixture

    • Thermostat malfunction (not fully open)

    • Radiator malfunction (clogging)

  • Improper engine coolant level

    • Leakage around heater unit in passenger compartment

  • Drive belt damage

CAUTION:

  • Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.

Related PIDs

Item (definition)

Unit/Condition

Definition

Condition/Specification (Reference)

ECT

°C, °F

Engine coolant temperature input from ECT sensor No.1

  • Displays ECT

V

ECT sensor No.1 voltage

    Ignition switched ON (engine off)

  • ECT is 92 °C {198 °F}: Approx. 0.65 V

    Idle (after warm up)

  • ECT is 93 °C {199 °F}: Approx. 0.64 V

    Racing (Engine speed is 2,000 rpm)

  • ECT is 92 °C {198 °F}: Approx. 0.66 V

    Racing (Engine speed is 4,000 rpm)

  • ECT is 93 °C {199 °F}: Approx. 0.64 V

Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION

1

INSPECT VEHICLE CONDITION FOR EFFECT ON MALFUNCTION

  • Verify how the customer drives the vehicle by asking the customer the following:

    • Engine speed is high and remains high for continuous long periods like when climbing a long, steep grade.

  • Is the engine generating excessive heat when driven?

Yes

Explain to the customer that the vehicle is normal and give them advice how to use vehicle and provide a specific example of the conditions in which the engine overheats.

No

Go to the next step.

2

VERIFY PCM DTC

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

Go to the next step.

3

DETERMINE IF MALFUNCTION CAUSE IS A/C SYSTEM OR OTHER

  • Start the engine and run it at idle speed.

  • Turn the A/C switch off.

  • Does the A/C compressor disengaged?

Yes

Go to the next step.

No

Perform the symptom troubleshooting “NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”.

(See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [SKYACTIV-G 2.0].)

4

INSPECT ECT SENSOR NO.1 SIGNAL

  • Access the ECT PID using the M-MDS.

    (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

  • Compare the ECT PID and low engine coolant temperature indicator light and high engine coolant temperature warning light operation.

  • Is the ECT PID value same as indicator/warning light readings?

Yes

Go to the next step.

No

Inspect the ECT sensor No.1.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G 2.0].)

5

INSPECT COOLING FAN CONTROL SYSTEM OPERATION

Yes

Go to the next step.

No

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

6

INSPECT COOLING SYSTEM CAP

Yes

Replace the cooling system cap.

No

Go to the next step.

7

INSPECT RELATED PART CONDITION

  • Inspect the following:

    • Engine coolant performance

    • Coolant leakage (engine internal, external)

    • Water and anti-freeze mixture

    • Thermostat (not fully open)

    • Radiator (clogging)

    • Fuses

  • Is there any malfunction?

Yes

Service if necessary.

  • Repeat this step.

No

Go to the next step.

8

VERIFY IF MALFUNCTION CAUSED BY LACK OF ENGINE COOLANT

Yes

Add engine coolant and verify that there is no engine coolant leakage.

(See ENGINE COOLANT REPLACEMENT [SKYACTIV-G 2.0].)

(See ENGINE COOLANT LEAKAGE INSPECTION [SKYACTIV-G 2.0].)

  • If there is any malfunction:

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

No

Go to the next step.

9

DETERMINE IF MALFUNCTION CAUSE IS THERMOSTAT OR OTHER

  • Verify the radiator hose tension.

    WARNING:

    • To prevent burns, use a cloth with your hand to verify the tension of the radiator hose.

  • After the engine warms up, does the engine coolant circulate to the radiator hose?

Yes

Go to Step 11.

No

Go to the next step.

10

INSPECT THERMOSTAT

Yes

Inspect the water pump.

No

Replace the thermostat.

(See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

11

INSPECT DRIVE BELT

Yes

Go to the next step.

No

Replace the drive belt.

(See DRIVE BELT REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

12

INSPECT RADIATOR FOR CLOGGING

  • Inspect for clogging in the radiator.

  • Is there any malfunction?

Yes

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

No

Replace the engine coolant.

(See ENGINE COOLANT REPLACEMENT [SKYACTIV-G 2.0].)

13

Verify the test results.

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

    (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.0].)

  • 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.

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