STOP AND START SYSTEM, Diagnostic DTC:P1541

DTC Code DTC Name
P1541 Brake Booster Sensor Circuit

DESCRIPTION

The engine stop and start ECU determines changes in the brake booster assembly pressure based on the voltage signal received from the vacuum sensor assembly in the brake booster assembly.

If the output value of the vacuum sensor assembly remains the same even though the brake booster assembly pressure changes when the brake pedal is operated or the vehicle is being driven, the engine stop and start ECU judges that the sensor is stuck.

When sticking of the sensor is detected, the engine stop and start ECU stores DTC P1541 and blinks the stop and start cancel indicator light.

DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate Memory
P1541 Brake Booster Sensor Circuit

Any of the following conditions are met (1 trip detection logic):


  • The change in vacuum is 0.3 kPa or less more than 3 times when the brake pedal is firmly depressed to stop the vehicle (deceleration of 0.15 G or more for 1 second or more).

  • The change in vacuum while stopping the vehicle 30 times from a speed of 30 km/h (19 mph) or more was 0.3 kPa or less

  • Vacuum sensor assembly

  • Brake booster assembly

  • Vacuum hose (Brake booster hose)

  • 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.

Click here


  1. Tech Tips


    • If the cable is disconnected from the battery terminal, stop and start control is prohibited until refresh charge is completed.

      In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item [Status of Battery Charge Control] changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery fluid temperature at 11°C (52°F) or higher, the refresh charge will be completed.)

    • If the GTS is not available and the Data List item [Status of Battery Charge Control] cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.

      If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.

    • After the refresh charge completes, turn the engine switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.

    • 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. Enter the following menus: Powertrain / Stop and Start / Data List / Brake Boost Pressure.


      Powertrain > Stop and Start > Data List
      Tester Display
      Brake Boost Pressure

    6. Drive the vehicle at 30 km/h (19 mph) or more and stop the vehicle. Repeat this driving pattern 30 times to allow the brake booster vacuum to change.

    7. Stop the vehicle.

    8. 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 battery terminal, stop and start control is prohibited until refresh charge is completed.

      In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item [Status of Battery Charge Control] changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery fluid temperature at 11°C (52°F) or higher, the refresh charge will be completed.)

    • If the GTS is not available and the Data List item [Status of Battery Charge Control] cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.

      If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.

    • After the refresh charge completes, turn the engine switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.


    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

Click here

CAUTION / NOTICE / HINT

Note


  • Before replacing the engine stop and start ECU, read the number of starter operations and total number of engine starts and write it into a new 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, airbag sensor assembly*1 or yaw rate and acceleration sensor*2, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.

    Click here


    • *1: for Optitron Meter Type

    • *2: for TFT Meter Type

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.

Click here

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Stop and Start / Trouble Codes.

    5. Read any other DTCs.


      Powertrain > Stop and Start > Trouble Codes
      Result
      Result Proceed to
      DTC P1541 is output A
      DTC P1541 and other DTCs output B

    B

    GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

    A

  2. READ VALUE USING GTS (BRAKE BOOST PRESSURE)


    1. Start the engine and warm it up.

    2. Turn the engine switch off. (*1)

    3. Turn the engine switch on (IG). (engine is stopped) (*2)

    4. Turn the GTS on.

    5. Enter the following menus: Powertrain / Stop and Start / Data List / Brake Boost Pressure. (*3)


      Powertrain > Stop and Start > Data List
      Tester Display
      Brake Boost Pressure

    6. Depress the brake pedal 5 times and read the changes in the following pressure value.

      OK
      Tester Display Condition Normal Condition
      Brake Boost Pressure

      • Engine switch on (IG)

      • Brake pedal depressed 5 times

      		 Changes by 20 kPa (150 mmHg, 5.91 in. Hg) or higher

      Note

      Because it is hard to cause variation in the internal pressure before and after depressing the brake pedal if the brake booster internal pressure is high before depressing the brake pedal, do not operate the brake pedal as much as possible between operations (*1) and (*3).

      Result
      Proceed to
      OK
      NG

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

  3. INSPECT VACUUM HOSE (BRAKE BOOSTER HOSE)


    1. Check the vacuum hose (brake booster hose) for cracks or clogging (visual check).

      Tech Tips

      If the braking force is abnormal, inspect the brake booster assembly.

      OK
      No cracks or clogging in the vacuum hose (brake booster hose).
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE VACUUM HOSE

    OK

  4. REPLACE VACUUM SENSOR ASSEMBLY


    1. Replace the vacuum sensor assembly.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  5. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Stop and Start / Trouble Codes.

    5. Clear the DTC.


      Powertrain > Stop and Start > Clear DTCs
      Result
      Proceed to
      NEXT

    NEXT

  6. CHECK DTC OUTPUT


    1. Start the engine and warm it up.

    2. Turn the GTS on.

    3. Enter the following menus: Powertrain / Stop and Start / Data List / Brake Boost Pressure.


      Powertrain > Stop and Start > Data List
      Tester Display
      Brake Boost Pressure

    4. Drive the vehicle at 30 km/h (19 mph) or more and stop the vehicle. Repeat this driving pattern 30 times to allow the brake booster vacuum to change.

    5. Stop the vehicle.

    6. Check that no DTCs are output.


      Powertrain > Stop and Start > Trouble Codes
      Result
      Result Proceed to
      DTCs are not output A
      DTC P1541 is output B

    A

    END

    B

    REPLACE ENGINE STOP AND START ECU Click here