Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Fuel Pump Control General Electrical Failure (P12D501)

DESCRIPTION

Refer to DTC P062712.

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MONITOR DESCRIPTION

The fuel pump control ECU monitors the fuel pump drive circuit.

When a malfunction is detected in the fuel pump drive circuit, the diagnosis output circuit in the fuel pump control ECU modifies the operation signal sent by the ECM to indicate that there is a malfunction.

When the fuel pump control ECU operation duty ratio is 3 to 65%, and short in the fuel pump circuit is detected for 3 seconds or more, the diagnosis output circuit in the fuel pump control ECU modifies the operation signal sent by the ECM to indicate that there is a malfunction and the ECM stores a 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 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).
7. Turn the Techstream on.
8. Put the engine in Inspection Mode (Maintenance Mode).

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9. Start the engine and wait 10 seconds or more [A].
10. Enter the following menus: Powertrain / Engine / Trouble Codes [B].
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: P12D501.
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 is malfunctioning.
    • If the judgment result is INCOMPLETE, run the engine at an engine speed of 2500 rpm or more for 10 seconds or more and check the DTC judgment result again.
    • [A] to [B]: 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 P062712.

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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:

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) Remove the fuel pump control ECU.

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

Standard Resistance:

HINT:

This procedure checks for an internal short of the fuel pump control ECU when its transistor is stuck on.

NG

REPLACE FUEL PUMP CONTROL ECU

OK

(a) Disconnect the K14 fuel pump control ECU connector.

(b) Connect the Techstream to the DLC3.

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

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine / Active Test / Fuel Pump Single Phase Energization.

(f) Operate the fuel pump control ECU using the Active Test function and measure the voltage according to the value(s) in the table below.

Standard Voltage:

HINT:

• *: This Active Test limits the fuel pump control ECU output duty cycle to 50%. Therefore, the output voltage of the fuel pump control ECU will be approximately 50% of the power source voltage (+B terminal).
• Before performing this inspection, check that the auxiliary battery voltage is between 11 and 14 V (not depleted).

NG

REPLACE FUEL PUMP CONTROL ECU

OK

(a) Disconnect the fuel pump control ECU connector.

(b) Disconnect the fuel pump (for low pressure side) connector.

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

Standard Resistance:

HINT:

Perform "Inspection After Repair" after replacing the fuel pump (for low pressure side).

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OK

REPLACE FUEL PUMP (FOR LOW PRESSURE SIDE)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR