Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Engine Coolant Pump Actuator Stuck (P26CB71)

DESCRIPTION

Refer to DTC P26CA12.

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*: As the frequency signal (WPI) is 4 Hz when the water inlet housing with water pump sub-assembly is stopped to enable the ECM to detect an open or short in the signal line, the water inlet housing with water pump sub-assembly speed will be displayed as approximately 160 rpm even when the pump is stopped. If there is an open in the WPI circuit, the water inlet housing with water pump sub-assembly speed will be displayed as 0 rpm.

MONITOR DESCRIPTION

The ECM receives a frequency signal (WPI) from the water inlet housing with water pump sub-assembly and calculates the speed of the water inlet housing with water pump sub-assembly. The ECM outputs an operation duty signal (WPO) to steplessly control the speed of the water inlet housing with water pump sub-assembly. If the duty signal (WPI) indicates that the water inlet housing with water pump sub-assembly is stopped even though the ECM is outputting an operation duty signal (WPO), the ECM judges that the water inlet housing with water pump sub-assembly is stuck and stores this DTC.

As the frequency signal (WPI) is 4 Hz when the water inlet housing with water pump sub-assembly is stopped to enable the ECM to detect an open or short in the signal line, the water inlet housing with water pump sub-assembly speed will be displayed as approximately 160 rpm even when the pump is stopped.

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 Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
5. Turn the power switch off and wait for at least 30 seconds.
6. Turn the power switch on (IG) [A].
7. Turn the Techstream on.
8. Put the engine in Inspection Mode (Maintenance Mode).

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9. Start the engine and maintain the engine speed at 2500 rpm or more for at least 40 seconds [B].
10. Enter the following menus: Powertrain / Engine / Trouble Codes [C].
11. 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.
12. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
13. Input the DTC: P26CB71.
14. Check the DTC judgment result.

    Techstream 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 has a malfunction.
    • If the judgment result is INCOMPLETE, perform steps [B] through [C] again.
    • [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

Refer to DTC P26CA12.

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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.)

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• 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:

• As the frequency signal (WPI) is 4 Hz when the water inlet housing with water pump sub-assembly is stopped to enable the ECM to detect an open or short in the signal line, the water inlet housing with water pump sub-assembly speed will be displayed as approximately 160 rpm even when the pump is stopped.
• Read Freeze Frame Data using the Techstream. 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) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

HINT:

If any DTCs other than P26CB71 are output, troubleshoot those DTCs first.

B

GO TO DTC CHART

A

(a) Check that the engine coolant level is between the FULL and LOW lines.

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A

GO TO STEP 6

B

(a) Check the areas around the engine and heater for engine coolant leaks.

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HINT:

If the engine oil is cloudy during the engine oil level gauge check, it means that engine coolant has entered the engine lubrication system.

OK:

No leaks.

NG

GO TO STEP 5

OK

(a) Fill the reservoir tank up to the FULL line with engine coolant.

NOTICE:

Make sure not to add engine coolant when the engine is hot.

NEXT

GO TO STEP 6

(a) Repair any engine coolant leaks.

HINT:

Add engine coolant and perform air bleeding after repair.

NEXT

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Active Test / Activate the Electric Water Pump / Data List / Electric Water Pump Speed.

(e) According to the display on the Techstream, read the Data List while performing the Active Test.

Standard:

OK

GO TO STEP 8

NG

(a) Disconnect the water inlet housing with water pump sub-assembly connector.

(b) Turn the power switch on (IG).

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

Standard:

HINT:

• *: When the connector of the water inlet housing with water pump sub-assembly is disconnected, the ECM will enter fail-safe mode. When the ECM is in fail-safe mode, a continuous duty signal will be output and the resistance will fluctuate as the transistor inside the ECM is turned on an off.
• If the resistance fluctuates while the ECM is in fail-safe mode after the connector of the water inlet housing with water pump sub-assembly is disconnected, it can be determined that the transistor is operating.
• If the transistor is not operating, the ECM may be malfunctioning.
• If the resistance fluctuates after turning the power switch on (IG), it can be determined that the ECM is in fail-safe mode.

NG

REPLACE ECM

OK

(a) Replace the water inlet housing with water pump sub-assembly.

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HINT:

When replacing any cooling system parts, if excessive deposits of rust or scale exist or the concentration of the engine coolant is abnormal, replace the engine coolant.

NEXT

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

(e) Turn the power switch off and wait for at least 30 seconds.

NEXT

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

(c) Read the DTCs.

HINT:

If no DTC is output, the repair has been successfully completed.

NEXT

END