Toyota Corolla Cross: Engine Coolant Temperature Sensor 1 Circuit Short to Ground (P011511)

DESCRIPTION

A thermistor, whose resistance value varies according to the engine coolant temperature, is built into the engine coolant temperature sensor. The structure of the sensor and its connection to the ECM are the same as those of the intake air temperature sensor.

The thermistor with a resistance that varies according to the temperature of the engine coolant. When the engine coolant temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see Fig. 1).

The engine coolant temperature sensor is powered by a 5 V supply from the THW terminal of the ECM, via resistor R.

Resistor R and the engine coolant temperature sensor are connected in series. When the resistance value of the engine coolant temperature sensor changes, according to changes in the engine coolant temperature, the voltage at terminal THW also varies.

HINT:

When DTC P011511 is stored, the ECM enters fail-safe mode. During fail-safe mode, the engine coolant temperature is estimated to be 80°C (176°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

HINT:

When a DTC is output, check the Data List item "Coolant Temperature" using the GTS.

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If the Data List displays a normal value, the normal value may be due to a temporary recovery from the malfunction condition. Check for intermittent problems.

MONITOR DESCRIPTION

The engine coolant temperature sensor is used to monitor the engine coolant temperature. The engine coolant temperature sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the engine coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance decreases. These variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature. If the engine coolant temperature sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the engine coolant temperature sensor circuit, illuminates the MIL and stores a DTC.

Example:

If the engine coolant temperature sensor output voltage is less than 0.142 V for 0.5 seconds or more, the ECM will illuminate the MIL and store this DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

CONFIRMATION DRIVING PATTERN

HINT:

• After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

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• When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

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1. Connect the GTS to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the GTS on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
5. Turn the ignition switch off and wait for at least 30 seconds.
6. Turn the ignition switch to ON [A].
7. Turn the GTS on.
8. Wait 0.5 seconds or more [B].
9. Enter the following menus: Powertrain / Engine / Trouble Codes [C].
10. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
12. Input the DTC: P011511.
13. Check the DTC judgment result.

    GTS Display	Description
    NORMAL	DTC judgment completed System normal
    ABNORMAL	DTC judgment completed System abnormal
    INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions

    HINT:

    • If the judgment result is NORMAL, the system is normal.
    • If the judgment result is ABNORMAL, the system is malfunctioning.
    • [A] to [C]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

• Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the freeze frame data and Vehicle Control History can be useful for troubleshooting.

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  (Select Powertrain in Health Check and then check the time stamp data.)

• If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.

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HINT:

• If DTC P011511 is stored, check that the engine does not overheat (DTC P011511 may be stored due to engine overheating).
• Read Freeze Frame Data using the GTS. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. When troubleshooting, Freeze Frame Data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

(a) Disconnect the engine coolant temperature sensor connector.

(b) Enter the following menus.

(c) According to the display on the GTS, read the Data List.

OK:

HINT:

Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.

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OK

REPLACE ENGINE COOLANT TEMPERATURE SENSOR

NG

(a) Disconnect the engine coolant temperature sensor connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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