ANTI-LOCK BRAKE SYSTEM, Diagnostic DTC:C1246/46, C1281/81

DTC Code DTC Name
C1246/46 Master Cylinder Pressure Sensor Malfunction
C1281/81 Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC)

DESCRIPTION

DTC C1281/81 can be deleted when the master cylinder pressure sensor sends a master cylinder pressure signal or the Test Mode ends. DTC C1281/81 is output only in the Test Mode.

DTC Code DTC Detection Condition Trouble Area
C1246/46

When any of the following is detected:


  1. When IG1 terminal voltage is 20 to 32 V, VCM terminal voltage is not between 4.3 and 5.8 V for 1.2 seconds or more.

  2. PMC terminal voltage is not between 0.14 and 4.75 V for 1.2 seconds or more.

  3. With the stop light switch off, either of the following continues for 5 seconds or more:


    • Vehicle speed is 10 km/h (6 mph) or more and PMC voltage is 0.86 V or more.

    • PMC voltage is less than 0.3 V.

  4. At a vehicle speed of 7 km/h (4.3 mph) or more, PMC terminal voltage does not change by 0.01 V or more for 30 seconds or more.

  5. At a vehicle speed of 10 km/h (6 mph) or more, noise occurs in PMC terminal voltage at least 7 times for 5 seconds.

  • Master cylinder pressure sensor

  • Master cylinder pressure sensor circuit

  • Stop light switch circuit

  • Skid control ECU
C1281/81 Detected only during Test Mode.

  • Stop light switch

  • Master cylinder pressure sensor

WIRING DIAGRAM

A01CID2E01

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK STOP LIGHT OPERATION


    1. Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.

      OK
      Condition Illumination Condition
      Brake pedal depressed ON
      Brake pedal released OFF

    NG

    INSPECT STOP LIGHT CIRCUIT

    OK

  2. READ VALUE ON INTELLIGENT TESTER (STOP LIGHT SWITCH)


    1. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    2. Connect the intelligent tester to the DLC3.

    3. Start the engine.

    4. Select the Data List mode on the intelligent tester Click here.

      ABS / VSC / TRC:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch / ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -

    5. Check that the stop light display observed on the intelligent tester changes when the brake pedal is depressed.

      OK
      When the brake pedal is depressed, the intelligent tester displays "ON".

    NG

    INSPECT SKID CONTROL ECU (STP TERMINAL) Click here

    OK

  3. READ VALUE ON INTELLIGENT TESTER (MASTER CYLINDER PRESSURE SENSOR)


    1. Select the Data List mode on the intelligent tester Click here.

      ABS / VSC / TRC:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Master Cylinder Sensor 1 Master cylinder pressure sensor 1 reading / min.: 0 V, max.: 5 V When brake pedal is released: 0.3 to 0.7 V Reading increases when brake pedal is depressed

    2. Check that the brake fluid pressure value of the master cylinder pressure sensor observed on the intelligent tester changes when the brake pedal is depressed.

      OK
      When the pedal is depressed, voltage displayed on the intelligent tester increases.

    NG

    INSPECT MASTER CYLINDER PRESSURE SENSOR Click here

    OK

  4. RECONFIRM DTC


    1. Turn the ignition switch off.

    2. Clear the DTC (See Pub. No. RM1008E, page 05-195).

    3. Start the engine.

    4. At a speed of 10 km/h (6 mph) or more, drive the vehicle and perform braking test (decelerate the vehicle by depressing the brake pedal).

    5. Check if the same DTC is recorded (See Pub. No. RM1008E, page 05-195).

      Result
      Result Proceed to
      DTC (C1246/46) is not output A
      DTC (C1246/46) is output B

    B

    REPLACE SKID CONTROL ECU

    A

    CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Click here

  5. INSPECT MASTER CYLINDER PRESSURE SENSOR


    1. A01CGTWE01

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      3 (VCM) - 1 (E2) Ignition switch ON 4.75 to 5.25 V

    2. Install the hydro LSPV gauge (SST) and bleed air.

    3. Start the engine.

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

      Standard voltage
      Tester Connection

      Fluid Pressure

      MPa (kgf/cm2, psi)

      		 Specified Condition
      2 (PMC) - 1 (E2) 0 (0, 0) 0.5 V
      2 (PMC) - 1 (E2) 9.8 (100, 1422) 2.5 V
      2 (PMC) - 1 (E2) 19.6 (200, 2844) 4.5 V

      Note

      Check the master cylinder pressure sensor signal after replacement Click here


    NG

    REPLACE MASTER CYLINDER PRESSURE SENSOR

    OK

  6. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - MASTER CYLINDER PRESSURE SENSOR)


    1. A01CHENE02

      Turn the ignition switch off.

    2. Disconnect the skid control ECU connector and the master cylinder pressure sensor connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      S12-24 (VCM) - M1-3 (VCM) Always Below 1 Ω
      S12-24 (VCM) - Body ground Always 10 kΩ or higher
      S12-25 (PMC) - M1-2 (PMC) Always Below 1 Ω
      S12-25 (PMC) - Body ground Always 10 kΩ or higher
      S12-15 (E2) - M1-1 (E2) Always Below 1 Ω
      S12-15 (E2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT SKID CONTROL ECU (SENSOR INPUT)


    1. A01CI3VE01

      Reconnect the skid control ECU connector.

    2. Turn the ignition switch to the ON position.

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      S12-24 (VCM) - Body ground Ignition switch ON 4.75 to 5.25 V

    NG

    REPLACE SKID CONTROL ECU

    OK

  8. INSPECT SKID CONTROL ECU (SENSOR OUTPUT)


    1. A01CI3VE02

      Turn the ignition switch off.

    2. Reconnect the master cylinder pressure sensor connector.

    3. Turn the ignition switch to the ON position.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      S12-25 (PMC) - Body ground Ignition switch ON, brake pedal released 0.3 to 0.7 V

      Note

      Check the master cylinder pressure sensor signal after replacement Click here


    NG

    REPLACE MASTER CYLINDER PRESSURE SENSOR

    OK

  9. RECONFIRM DTC


    1. Turn the ignition switch off.

    2. Clear the DTC (See Pub. No. RM1008E, page 05-195).

    3. Start the engine.

    4. At a speed of 10 km/h (6 mph) or more, drive the vehicle and perform braking test (decelerate the vehicle by depressing the brake pedal).

    5. Check if the same DTC is recorded (See Pub. No. RM1008E, page 05-195).

      Result
      Result Proceed to
      DTC (C1246/46) is not output A
      DTC (C1246/46) is output B

    B

    REPLACE SKID CONTROL ECU

    A

    CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Click here

  10. INSPECT SKID CONTROL ECU (STP TERMINAL)


    1. A01CIMFE02

      Turn the ignition switch off.

    2. Disconnect the skid control ECU connector.

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      S13-1 (STP) - Body ground Stop light switch ON (Brake pedal depressed) 16 to 32 V
      S13-1 (STP) - Body ground Stop light switch OFF (Brake pedal released) Below 3 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

    OK

    REPLACE SKID CONTROL ECU