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 input value from 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.

DTC No. DTC Detection Condition Trouble Area
P1541

The following condition is met (1 trip detection logic):


  • Vacuum does not change while brake pedal is operated 3 times in a row.

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


  • Vehicle speed exceeds 30 km/h (18.6 mph) 30 times or more.

  • Changes in vacuum (difference between the maximum and minimum values) is 0.3 kPa (2 mmHg, 0.09 in.Hg) or less.

  • Vacuum sensor assembly

  • Brake booster assembly

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

  • Engine stop and start ECU

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. CONFIRMATION AFTER TROUBLESHOOTING

    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 60 minutes until refresh charge is completed and stop and start control operation is permitted.

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


    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.

    4. Start the engine and warm it up.

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

    6. Drive the vehicle at 30 km/h (18.6 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.

  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 60 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 the 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

Refer to DTC P1540 Click here.

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

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 the other DTCs.

      Result
      Result Proceed to
      Other DTCs are not output A
      Other DTCs are 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). (*2)

      Tech Tips

      Do not start the engine.

    4. Turn the GTS on.

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

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

      OK
      GTS 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).


    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

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


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

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

    NG

    REPLACE CHECK VALVE TO CONNECTOR TUBE HOSE

    OK

  4. REPLACE VACUUM SENSOR ASSEMBLY


    1. Replace the vacuum sensor assembly Click here.


    NEXT

  5. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the GTS on.

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

    4. Clear the DTC.


    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.

    4. Drive the vehicle at 30 km/h (18.6 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.

      Result
      Result Proceed to
      DTC is not output A
      DTC is output B

    A

    END

    B

    REPLACE ENGINE STOP AND START ECU Click here