VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1241

DTC Code DTC Name
C1241 Low Power Supply Voltage Malfunction

DESCRIPTION

If a malfunction is detected in the power supply circuit, the skid control ECU (brake actuator assembly) stores this DTC and the fail-safe function prohibits ABS operation. This DTC is stored when the +BS terminal voltage deviates due to a malfunction in the power supply or charging circuit such as the battery or alternator circuit, etc. The DTC is cleared when the +BS terminal voltage returns to normal.

DTC No.

DTC Detection Condition

Trouble Area

C1241

Any of the following is detected:

  1. The vehicle speed is 6 km/h (4 mph) or more and the +BS terminal voltage (soft low voltage) is less than 9.6 V for 1 second or more.

  2. The vehicle speed is 6 km/h (4 mph) or more and the +BS terminal voltage (hard low voltage) is less than 6.9 V for 1 second or more.

  3. The vehicle speed is 15 km/h (9 mph) or more, the +BS terminal voltage is 9.6 V or more, the skid control ECU (brake actuator assembly) turns on more than one valve at the same time within a short period of time and the valve relay supply voltage drop exceeds the threshold.*

  4. The +BS terminal voltage is less than 6.7 V and the skid control ECU (brake actuator assembly) judges that power supply voltage is abnormal for 0.06 seconds or more.

  • ABS NO. 2 fuse

  • Battery

  • Charging system

  • Power source circuit

  • Ground circuit

  • Internal power supply circuit of the skid control ECU (Brake actuator assembly)

  • *: The skid control ECU (brake actuator assembly) monitors the resistance of the power source line at the +BS terminal. A malfunction is detected when an abnormality occurs in the +BS terminal wire harness or its connection and the skid control ECU (brake actuator assembly) determines that the wiring resistance at the +BS terminal exceeds the standard resistance.

WIRING DIAGRAM

C323089E02

CAUTION / NOTICE / HINT

Note:

  • When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration (Click here).

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

  1. CHECK BATTERY

    1. Check the battery voltage.

      Standard voltage

      11 to 14 V

      Result

      Result

      Proceed to

      OK

      A

      NG (for 1ZR-FAE)

      B

      NG (for 2ZR-FAE)

      C

      NG (for 1WW)

      D

    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY CHARGING SYSTEM AND BATTERY

    (Click here)

    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY CHARGING SYSTEM AND BATTERY

    (Click here)

    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY CHARGING SYSTEM AND BATTERY

    (Click here)

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE TERMINAL)

    1. U123606E02

      Make sure that there is no looseness at the locking part and the connecting part of the connector.

    2. Disconnect the A78 (for CVT) or A79 (except CVT) skid control ECU (brake actuator assembly) connector.

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

      Standard Voltage (for CVT)

      Tester Connection

      Condition

      Specified Condition

      A78-25 (+BS) - Body ground

      Always

      11 to 14 V

      A78-25 (+BS) - A78-38 (GND1)

      Always

      11 to 14 V

      A78-28 (IG1) - Body ground

      Ignition switch ON

      11 to 14 V

      A78-28 (IG1) - A78-38 (GND1)

      Ignition switch ON

      11 to 14 V

      Standard Voltage (except CVT)

      Tester Connection

      Condition

      Specified Condition

      A79-1 (+BS) - Body ground

      Always

      11 to 14 V

      A79-1 (+BS) - A79-14 (GND1)

      Always

      11 to 14 V

      A79-4 (IG1) - Body ground

      Ignition switch ON

      11 to 14 V

      A79-4 (IG1) - A79-14 (GND1)

      Ignition switch ON

      11 to 14 V
      Table 1. Text in Illustration

      *A

      for CVT

      *B

      except CVT

      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

    Result

    Result

    Proceed to

    OK

    A

    NG (for +BS circuit)

    B

    NG (w/o Stop and Start System for IG1 circuit)

    C

    NG (w/ Stop and Start System for IG1 circuit)

    D

    CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - ENGINE ROOM NO. 1 RELAY BLOCK)Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    INSPECT STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT)

    (Click here)

  3. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

    1. U123607E01

      Turn the ignition switch off.

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

      Standard Resistance (for CVT)

      Tester Connection

      Condition

      Specified Condition

      A78-38 (GND1) - Body ground

      Always

      Below 1 Ω

      Standard Resistance (except CVT)

      Tester Connection

      Condition

      Specified Condition

      A79-14 (GND1) - Body ground

      Always

      Below 1 Ω
      Table 2. Text in Illustration

      *A

      for CVT

      *B

      except CVT

      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

  4. RECONFIRM DTC

    1. Reconnect the A78 (for CVT) or A79 (except CVT) skid control ECU (brake actuator assembly) connector.

    2. Clear the DTCs (Click here).

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Perform a road test.

    6. Check if the same DTC is output (Click here).

      Result

      Result

      Proceed to

      DTC C1241/41 is not output.

      A

      DTC C1241/41 is output.

      B
      Tip:

      If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step (Click here).

    USE SIMULATION METHOD TO CHECK

    (Click here)

    REPLACE BRAKE ACTUATOR ASSEMBLY

    (Click here)

  5. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - ENGINE ROOM NO. 1 RELAY BLOCK)

    1. Turn the ignition switch off.

    2. Disconnect the 1N (w/o Stop and Start System) or 1R (w/ Stop and Start System) engine room NO. 1 relay block connector.

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

      Standard Resistance (for CVT)

      Table 3. w/o Stop and Start System

      Tester Connection

      Condition

      Specified Condition

      A78-25 (+BS) - Engine room NO. 1 relay block 1N terminal 1

      Always

      Below 1 Ω

      Standard Resistance (except CVT)

      Table 4. w/o Stop and Start System

      Tester Connection

      Condition

      Specified Condition

      A79-1 (+BS) - Engine room NO. 1 relay block 1N terminal 1

      Always

      Below 1 Ω
      Table 5. w/ Stop and Start System

      Tester Connection

      Condition

      Specified Condition

      A79-1 (+BS) - Engine room NO. 1 relay block 1R terminal 1

      Always

      Below 1 Ω
      Tip:

      • Even if the resistance between the skid control ECU (brake actuator assembly) and the engine room NO. 1 relay block is normal, there may be an abnormality in the resistance of the wiring between the battery and the engine room NO. 1 relay block.

        Therefore, be sure to inspect the circuit between the battery and the engine room NO. 1 relay block before replacing the skid control ECU (brake actuator assembly).

    REPLACE BRAKE ACTUATOR ASSEMBLY

    (Click here)

    REPAIR OR REPLACE WIRE HARNESS OR ENGINE ROOM NO. 1 RELAY BLOCK