STOP AND START SYSTEM(for 2WW), Diagnostic DTC:P1540

DTC Code DTC Name
P1540 Brake Booster Sensor Circuit (Open or Short)

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 engine stop and start ECU judges that the signal received from the vacuum sensor assembly is abnormal, it stores DTC P1540 and blinks the stop and start cancel indicator light.

A280541E05

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Memory

P1540

Brake Booster Sensor Circuit (Open or Short)

The following conditions continue for 2 seconds or more (1 trip detection logic):

  • Open or short in vacuum sensor assembly circuit

  • Ignition switch ON

  • Vacuum sensor assembly

  • Engine stop and start ECU

  • Wire harness or connector

Blinks

DTC stored

CONFIRMATION DRIVING PATTERN

Tip:

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. CONFIRMATION AFTER TROUBLESHOOTING

    Tip:

    • If the cable is disconnected from the negative (-) battery terminal, stop and startcontrol is prohibited until refresh charge is completed. In this case, drive the vehicleapproximately 5 to 60 minutes until refresh charge is completed and stop and startcontrol operation is permitted.

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

    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 allow it to idle for 15 seconds or more.

    5. Stop the engine and turn the ignition switch to ON.

    6. Turn the GTS on.

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

    8. While depressing the brake pedal several times, check that the Brake Boost Pressure value changes.

    9. 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 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. Stop the vehicle, move the shift lever to neutral and release the clutch pedal.

    5. Allow the engine to stop by stop and start control.

    6. Depress the clutch pedal and start the engine.

WIRING DIAGRAM

A285528E18

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.

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

    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 VACUUM SENSOR ASSEMBLY (PB TERMINAL VOLTAGE)

    A346331C69

    *a

    Component with harness connected

    (Engine Stop and Start ECU)

    -

    -

    1. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A66-13 (PB) - A66-3 (BRE2)

      Ignition switch ON

      Higher than 0.6 V or below 4.7 V

    Result

    Proceed to

    OK

    NG
    OK

    USE SIMULATION METHOD TO CHECK

    Click hereClick here

    NG

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - VACUUM SENSOR ASSEMBLY)

    1. Disconnect the A66 engine stop and start ECU connector.

    2. Disconnect the A60 vacuum sensor assembly connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A66-13 (PB) - A60-2 (PB)

      Always

      Below 1 Ω

      A66-14 (BRVC) - A60-3 (VC)

      Always

      Below 1 Ω

      A66-3 (BRE2) - A60-1 (E2)

      Always

      Below 1 Ω

      A66-13 (PB) - Body ground

      Always

      10 kΩ or higher

      A66-14 (BRVC) - Body ground

      Always

      10 kΩ or higher

      A66-3 (BRE2) - Body ground

      Always

      10 kΩ or higher

      A60-2 (PB) - Body ground

      Always

      10 kΩ or higher

      A60-3 (VC) - Body ground

      Always

      10 kΩ or higher

      A60-1 (E2) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK ENGINE STOP AND START ECU (BRVC TERMINAL VOLTAGE)

    A346331C70

    *a

    Component with harness connected

    (Engine Stop and Start ECU)

    -

    -

    1. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A66-14 (BRVC) - A66-3 (BRE2)

      Ignition switch ON

      4.75 to 5.25 V

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE ENGINE STOP AND START ECU

    Click here

    OK

  4. REPLACE VACUUM SENSOR ASSEMBLY

    1. Replace the vacuum sensor assembly.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  5. CHECK DTC 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. Check that no DTCs are output.

      Powertrain > Stop and Start > Trouble Codes

      Result

      Result

      Proceed to

      DTCs are not output

      A

      DTC P1540 is output

      B
    A

    END

    B

    REPLACE ENGINE STOP AND START ECU

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