SFI SYSTEM, Diagnostic DTC:C1478

DTC Code DTC Name
C1478 Brake Booster Pressure Sensor Circuit Stuck

DESCRIPTION

The ECM detects changes in the brake booster assembly pressure based on the voltage signal received from the vacuum sensor assembly installed to the brake booster assembly.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

C1478

Brake Booster Pressure Sensor Circuit Stuck

The signal from the vacuum sensor assembly remains the same for 1.2 seconds or more even though the brake pedal has been operated or the vehicle is being driven (1 trip detection logic).

  • Vacuum sensor assembly

  • Brake booster assembly

  • Vacuum hose assembly (brake booster hose)

  • ECM

Does not come on

DTC stored

MONITOR DESCRIPTION

If the brake pedal has been operated or the vehicle is being driven and the signal from the vacuum sensor assembly remains the same even though the brake booster assembly pressure should have changed, the ECM will determine that the vacuum sensor assembly is stuck and store DTC C1478.

CONFIRMATION DRIVING PATTERN

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

DTC C1478 is detected when accelerate the vehicle from rest to approximately 30 km/h (18.65 mph) or more and then decelerate the vehicle. (Repeating this pattern 30 times will cause the brake booster pressure to change.)

CAUTION / NOTICE / HINT

Note:

After replacing the ECM, perform idle learning.

Click here

Tip:

Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

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 / Engine and ECT / Trouble Codes.

    5. Check for other DTCs.

    Result

    Result

    Proceed to

    DTC C1478 is output

    A

    DTC C1478 and other DTCs are output

    B
    Tip:

    If any DTCs other than P1478 are output, troubleshoot those DTCs first.

    B

    GO TO DTC CHART

    Click here

    A

  2. READ VALUE USING GTS (BRAKE BOOST PRESSURE SENSOR)

    1. Start the engine and warm it up (until the engine coolant temperature 75°C (167°F) or higher) with all the accessories switched off.

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

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON. (*2)

    5. Turn the GTS on.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Brake Boost Pressure Sensor. (*3)

      Powertrain > Engine and ECT > Data List

      Tester Display

      Brake Boost Pressure Sensor

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

    Standard

    GTS Display

    Condition

    Specified Condition

    Brake Boost Pressure Sensor

    • Ignition switch ON (Engine is stopped)

    • Brake pedal depressed 5 times

    Changes by 0.6 V or higher
    Note:

    Avoid depressing the brake pedal while performing step (*1) through (*3) as the brake booster pressure will be high before depressing the brake pedal and the change in pressure will become smaller each time brake pedal is depressed.

    Result

    Proceed to

    OK

    NG
    OK

    CHECK FOR INTERMITTENT PROBLEMS

    Click here

    NG

  3. INSPECT VACUUM HOSE ASSEMBLY (BRAKE BOOSTER HOSE)

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

      Tip:

      When the actual brake force is insufficient, check the brake booster assembly.

      OK

      No cracks or clogging in the vacuum hose assembly (brake booster hose).

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE VACUUM HOSE ASSEMBLY

    OK

  4. REPLACE VACUUM SENSOR ASSEMBLY

    1. Replace the vacuum sensor assembly.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  5. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine and ECT > Clear DTCs

    5. Turn the ignition switch off and wait for at least 30 seconds.

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

    8. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

    9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    10. Read the DTCs.

      Powertrain > Engine and ECT > Trouble Codes

    Result

    Result

    Proceed to

    DTCs are not output

    A

    DTC C1478 is output

    B
    A

    END

    B

    REPLACE ECM

    Click here