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

  • Check valve to connector tube hose (Brake booster hose)

  • Engine stop and start ECU

Blinks

DTC stored

CONFIRMATION DRIVING PATTERN

Tip:

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

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  1. Tip:

    • 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 ignition switch to ON 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

    Tip:

    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. Stop the vehicle, move the shift lever to neutral and release the clutch pedal. (for Manual Transaxle)

    5. Depress the brake pedal and stop the vehicle. (for CVT)

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

    7. Depress the clutch pedal and start the engine. (for Manual Transaxle)

    8. Release the brake pedal with the shift lever in D to start the engine. (for CVT)

WIRING DIAGRAM

Refer to DTC P1540.

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CAUTION / NOTICE / HINT

Note:

  • 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.

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

    Click here

Tip:

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 ANY OTHER DTCS OUTPUT

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

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

    5. Read the 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

  2. READ VALUE USING GTS (BRAKE BOOST PRESSURE)

    1. Start the engine and warm it up.

    2. Turn the ignition switch off.

    3. Turn the ignition switch to ON.

    4. Turn the GTS on.

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

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

      Powertrain > Stop and Start > Data List

      Tester Display

      Measurement Item

      Normal Condition

      Brake Boost Pressure

      Condition:

      • Ignition switch ON

      • Brake pedal depressed 5 times

      Changes by 20 kPa (0.2 kgf/cm2, 2.9 psi) or higher

      Powertrain > Stop and Start > Data List

      Tester Display

      Brake Boost Pressure

    Result

    Proceed to

    OK

    NG
    OK

    USE SIMULATION METHOD TO CHECK

    Click hereClick hereClick hereClick here

    NG

  3. INSPECT CHECK VALVE TO CONNECTOR TUBE HOSE (BRAKE BOOSTER HOSE)

    1. Check the check valve to connector tube hose (brake booster hose) for cracks or clogging (visual check).

      Tip:

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

      OK

      No cracks or clogging in the check valve to connector tube hose (brake booster hose).

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE CHECK VALVE TO CONNECTOR TUBE 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 ignition switch to ON.

    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.

      Click here

      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

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