STOP AND START SYSTEM, Diagnostic DTC:P0641

DTC Code DTC Name
P0641 Sensor Reference Voltage "A" Circuit / Open

DESCRIPTION

When the sensor power source voltage is too low, the engine stop and start ECU stores DTC P0641 and blinks the stop and start cancel indicator light.

DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate Memory
P0641 Sensor Reference Voltage "A" Circuit / Open

The following condition continues for 0.5 seconds or more (1 trip detection logic):


  • Sensor power source voltage is below 4.0 V.

  • Wire harness or connector

  • Engine stop and start ECU

 Blinks DTC stored

CONFIRMATION DRIVING PATTERN

Tech Tips

DTCs for the stop and start system are not cleared even if the malfunction has been repaired. After repairing the malfunction, be sure to clear the DTCs.

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  1. Tech Tips


    • If the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 40 minutes until refresh charge is completed and stop and start control operation is permitted.

    • Allow the engine to idle for 3 minutes after it is warmed up and check that the engine idle speed is within 50 rpm of the target idle speed.

    CONFIRMATION AFTER TROUBLESHOOTING


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG) and turn the GTS on.

    3. Clear the DTCs.

      Click here


      Powertrain > Stop and Start > Clear DTCs

    4. Start the engine and warm it up.

    5. Drive the vehicle at 7 km/h (4.3 mph) or more.

      CAUTION:

      When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

    6. Depress the brake pedal and stop the vehicle.

    7. Keep the engine stopped by stop and start control for 1 second or more. (Keep the shift lever in D.)

    8. Release the brake pedal with the shift lever in D to start the engine.

      Tech Tips

      If the engine cranks slowly when the engine is restarted, it can be determined that the battery voltage is low.

    9. Check that DTCs are not output.

      Click here


      Powertrain > Stop and Start > Trouble Codes

  2. STOP AND START SYSTEM OPERATION CHECK

    Tech Tips

    If the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 40 minutes until refresh charge is completed and stop and start control operation is permitted.


    1. Start the engine and warm it up.

    2. Turn the air conditioning system off.

    3. Drive the vehicle at 7 km/h (4.3 mph) or more.

      CAUTION:

      When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

    4. Depress the brake pedal and stop the vehicle.

    5. Allow the engine to stop by stop and start control. (Keep the shift lever in D.)

    6. Release the brake pedal with the shift lever in D to start the engine.

WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Note


  • for 8AR-FTS:

    Before replacing the engine stop and start ECU, read the number of starter operations and write it into a new engine stop and start ECU.

    Click here

  • for 3ZR-FAE:

    When replacing the engine stop and start ECU with a new one, make sure to download the previous status (number of starter operations) of the old engine stop and start ECU. After replacing the engine stop and start ECU, turn the engine switch on (IG) and wait 20 seconds, then confirm that "OK" is displayed for the Data List item "Oper Prohibition (O/P Air Bleeding)". Then upload the previous status (number of starter operations) to the engine stop and start ECU.

    Click here

  • After replacing the engine stop and start ECU or air conditioning amplifier assembly, reset and perform learning of the air conditioning information in the engine stop and start ECU.

    Click here

  • After replacing the engine stop and start ECU or airbag ECU assembly, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

Tech Tips

Using the GTS, read the freeze frame data before troubleshooting. System condition information is recorded as freeze frame data the moment a DTC is stored. This information can be useful when troubleshooting.

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PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - BATTERY)


    1. Disconnect the A37 engine stop and start ECU connector.

    2. A01HG2UC28
      *a

      Front view of wire harness connector

      (to Engine Stop and Start ECU)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A37-7 (BIN) - Body ground Always 9.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - BODY GROUND)


    1. Disconnect the A37 engine stop and start ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A37-8 (GND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR