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

  • Check valve to connector tube hose (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


  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON.

  3. Turn the GTS on.

  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

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

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

  7. Turn the GTS on.

  8. Enter the following menus: Powertrain / Engine and ECT / Data List / Brake Boost Pressure Sensor.

  9. 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:

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

  10. Stop the vehicle.

  11. Turn the ignition switch to ON.

  12. Turn the GTS on.

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

  14. Read the pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  15. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  16. Input the DTC: C1478.

  17. Check the DTC judgment result.

    GTS Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions
    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result shows INCOMPLETE or N/A, perform the Confirmation Driving Pattern and check the DTC judgment result again.

CAUTION / NOTICE / HINT

Tech Tips

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

    B

    GO TO DTC CHART Click here

    A

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


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

    5. Stop the engine. (*1)

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

    7. Turn the GTS on. (*3)

    8. Enter the following menus: Powertrain / Engine and ECT / Data List / Brake Boost Pressure Sensor. (*4)

    9. 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

      • Brake pedal depressed 5 times

      		 Changes by 0.6 V or higher

      Note

      If the pressure inside the brake booster is high before performing the brake pedal operation procedure, it becomes difficult to cause changes in the pressure values before and after brake pedal operation, so avoid depressing the brake pedal as much as possible during steps (*1) to (*4).

      Result
      Proceed to
      OK
      NG

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click 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).

      Tech Tips

      When the actual brake force is insufficient, check 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. 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.

    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.

      Result
      Result Proceed to
      DTCs are not output A
      DTC C1478 is output B

    A

    END

    B

    REPLACE ECM Click here