ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1311, C1312

DTC Code DTC Name
C1311 Open Circuit in Main Relay 1
C1312 Short Circuit in Main Relay 1

DESCRIPTION

The main relay supplies power to the switching solenoid and the linear solenoid.

The main relay remains on for approximately 2 minutes after the power switch is turned off and the input of brake pedal operation signals stops, and supplies power to the system to keep it ready to operate.

DTC No. Detection Item INF Code DTC Detection Condition Trouble Area Note
C1311 Open Circuit in Main Relay 1 1

Either of the following is detected:


  1. When the power switch is on (READY):

    The BS terminal voltage is less than 3.5 V for 0.05 seconds or more, when the IG1 terminal voltage is 9.5 V or more and operation of the main relay is requested.

  2. When the power switch is off:

    The BS terminal voltage is less than 3.5 V for 0.05 seconds or more, when operation of the main relay is requested.

  • Open or short in main relay circuit

  • Skid control ECU (brake booster with master cylinder assembly)

 Electronically controlled brake system DTC
C1312 Short Circuit in Main Relay 1 2 The BS terminal voltage is 3.5 V or more for 4.5 seconds or more, when operation of the main relay is requested.

  • Short in main relay circuit

  • Main relay internal stuck

  • Skid control ECU (brake booster with master cylinder assembly)

 Electronically controlled brake system DTC
DTC Detection Conditions: C1311 INF Code: 1
Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition When the power switch is on (READY), the IG1 terminal voltage is 9.5 V or more. ○ -
When the power switch is off. - ○
Malfunction Status The BS terminal voltage is less than 3.5 V, when operation of the main relay is requested. ○ -
The BS terminal voltage is less than 3.5 V, when operation of the main relay is requested. - ○
Detection Time 0.05 seconds or more 0.05 seconds or more
Number of Trips 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

Refer to DTCs C1241 and C1242.

Click here

CAUTION / NOTICE / HINT

Note


  • After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".

    Click here

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

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS (MAIN RELAY)


    1. Select the Active Test on the GTS.

      Click here


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Main Relay Main relay Relay ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      ECB Main Relay

    2. Select the Data List on the GTS.

      Click here


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      ECB Main Relay Main relay operation request ON or OFF

      ON: Relay on

      OFF: Relay off

      		 ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      ECB Main Relay

    3. Check that the condition of the main relay observed on the GTS changes according to GTS operation.

      Result
      Result Proceed to
      Main relay in the Data List turns ON/OFF using the Active Test. A
      Main relay in the Data List does not change using the Active Test. B

    B

    CHECK HARNESS AND CONNECTOR (+BI TERMINAL) Click here

    A

  2. CHECK HARNESS AND CONNECTOR (BS TERMINAL)


    1. A005NB5C83
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      Turn the power switch off.

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

      OK
      The connector is securely connected.

    3. Disconnect the A39 skid control ECU (brake booster with master cylinder assembly) connector.

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A39-52 (BS) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BS CIRCUIT)

    OK

  3. RECONFIRM DTC


    1. Reconnect the A39 skid control ECU (brake booster with master cylinder assembly) connector.

    2. Clear the DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    3. Turn the power switch off.

    4. Turn the power switch on (IG).

    5. Check if the same DTC is output.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      DTCs C1311 and C1312 are not output. A
      DTCs C1311 and/or C1312 are output. (for LHD) B
      DTCs C1311 and/or C1312 are output. (for RHD) C

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    C

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

  4. CHECK HARNESS AND CONNECTOR (+BI TERMINAL)


    1. A001RR7C84
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      Turn the power switch off.

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

      OK
      The connector is securely connected.

    3. Disconnect the A39 skid control ECU (brake booster with master cylinder assembly) connector.

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A39-15 (+BI1) - Body ground Always 11 to 14 V
      A39-5 (+BI2) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (+BI CIRCUIT)

    OK

  5. CHECK HARNESS AND CONNECTOR (BS TERMINAL)


    1. A005NB5C83
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A39-52 (BS) - Body ground Always 11 to 14 V
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BS CIRCUIT)