Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM1000000026JSM
Model Year Start: 2023 Model: Corolla Prod Date Range: [09/2022 -           ]
Title: 2ZR-FXE (ENGINE CONTROL): SFI SYSTEM: P26CA12; Engine Coolant Pump Circuit Short to Battery; 2023 - 2025 MY Corolla Corolla HV [09/2022 -        ]

DTC

P26CA12

Engine Coolant Pump Circuit Short to Battery

DESCRIPTION

The ECM calculates the necessary cooling amount based on the engine coolant temperature, engine speed and vehicle speed, and controls the engine water pump assembly accordingly. The engine water pump assembly controls the speed of the engine water pump assembly steplessly and optimally based on a duty cycle signal sent by the ECM, which reduces engine warm-up time, improves fuel efficiency and reduces cooling loss.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P26CA12

Engine Coolant Pump Circuit Short to Battery

The operation duty ratio signal (WPO) of the engine water pump assembly is a certain value or more when the engine water pump assembly operation signal is being output (1 trip detection logic).

  • Short in engine water pump assembly (water inlet housing) circuit
  • Engine water pump assembly (water inlet housing)
  • ECM

Comes on

DTC stored

  • SAE Code: P26CD
  • DTC for Mexico Models: Applies

Related Data List

DTC No.

Data List

P26CA12

  • Coolant Temperature
  • Electric Water Pump Target Speed
  • Electric Water Pump Speed

MONITOR DESCRIPTION

The ECM outputs an operation duty signal (WPO) to steplessly control the speed of the engine water pump assembly. The ECM outputs an operation duty signal (WPO) to the engine water pump assembly and monitors the actual duty signal (WPO) being output. When the actual operation duty signal (WPO) exceeds a certain value when outputting an operation duty signal (WPO) to the engine water pump assembly, the ECM detects a malfunction and stores a DTC.

MONITOR STRATEGY

Related DTCs

P26CD: Engine water pump circuit range check (High voltage)

Required Sensors/Components (Main)

Engine water pump assembly

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

3 seconds

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

All of the following conditions are met

-

Auxiliary battery voltage

8 V or higher

Ignition switch

On

Time after Ignition switch off to ON

0.5 seconds or more

Output duty cycle

30 to 85%

Engine water pump circuit pulse input fail (P26CA)

Not detected

TYPICAL MALFUNCTION THRESHOLDS

Both of the following conditions are met

-

Engine water pump assembly output terminal voltage level

High

Engine water pump assembly output signal

No signal

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.

    Click here 2023 - 2025 MY Corolla Corolla HV [09/2022 -        ]; 2ZR-FXE (ENGINE CONTROL): SFI SYSTEM: DTC CHECK / CLEAR

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

    Click here 2023 - 2025 MY Corolla Corolla HV [09/2022 -        ]; 2ZR-FXE (ENGINE CONTROL): SFI SYSTEM: DTC CHECK / CLEAR

  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. Put the engine in Inspection Mode (Maintenance Mode).

    Click here 2019 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 -        ]; INTRODUCTION: REPAIR INSTRUCTION: INSPECTION MODE PROCEDURE

  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: P26CA12.
  14. 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 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

CAUTION / NOTICE / HINT

NOTICE:

  • Vehicle Control History may be stored in the hybrid vehicle control ECU 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.

    Click here 2023 - 2025 MY Corolla HV [09/2022 -        ]; HYBRID / BATTERY CONTROL: HYBRID CONTROL SYSTEM (for LITHIUM-ION BATTERY with PA10): VEHICLE CONTROL HISTORY (RoB)

    (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, 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.

    Click here 2023 - 2025 MY Corolla HV [09/2022 -        ]; HYBRID / BATTERY CONTROL: HYBRID CONTROL SYSTEM (for LITHIUM-ION BATTERY with PA10): VEHICLE CONTROL HISTORY (RoB)

HINT:

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

1.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING))

(a) Disconnect the engine water pump assembly (water inlet housing) connector.

(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

C126-3 (SWP) - Body ground

Ignition switch ON

Below 1 V

NG

GO TO STEP 3

OK

2.

INSPECT ECM (INTERNAL CIRCUIT)

(a) Disconnect the engine water pump assembly (water inlet housing) connector.

(b) Perform the Active Test using the GTS.

Powertrain > Engine > Active Test

Tester Display

Activate the Electric Water Pump

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

Standard:

Tester Connection

Condition

Specified Condition

C126-3 (SWP) - Body ground

During Active Test

Resistance fluctuates*

HINT:

  • *: Using the Active Test, duty control of the transistors in the ECM will be performed. Due to the duty control, resistance of the SWP terminal will be unstable during the Active Test. If the resistance fluctuates while performing the Active Test, it can be determined that the transistor is operating. If the transistor does not operate during the Active Test, the ECM may be malfunctioning.
OK

REPLACE ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING)

NG

REPLACE ECM 2023 MY Corolla Corolla HV [09/2022 - 11/2022]; 2ZR-FXE (ENGINE CONTROL): ECM: REMOVAL 2023 - 2025 MY Corolla Corolla HV [11/2022 -        ]; 2ZR-FXE (ENGINE CONTROL): ECM: REMOVAL

3.

CHECK HARNESS AND CONNECTOR (ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING) - ECM)

(a) Disconnect the engine water pump assembly (water inlet housing) connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

C126-3 (SWP) or C147-71 (WPO) - Other terminals

Always

10 kΩ or higher

OK

REPLACE ECM 2023 MY Corolla Corolla HV [09/2022 - 11/2022]; 2ZR-FXE (ENGINE CONTROL): ECM: REMOVAL 2023 - 2025 MY Corolla Corolla HV [11/2022 -        ]; 2ZR-FXE (ENGINE CONTROL): ECM: REMOVAL

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR