ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C146C, C146D

DTC Code DTC Name
C146C Open Circuit in ABS Motor Relay Circuit
C146D Short Circuit in ABS Motor Relay Circuit

DESCRIPTION

The ABS motor relay is built into the brake booster with master cylinder assembly.

During ABS, TRC, VSC or brake assist operation, the skid control ECU (brake booster with master cylinder assembly) turns on the ABS motor relay to run the pump motor in the brake actuator assembly.

When any DTC related to the ABS motor is stored, the IC built into the skid control ECU (brake booster with master cylinder assembly) operates in fail-safe mode.

When the supplied voltage to the BM terminal of the ABS motor relay is excessively low due to an auxiliary battery or charging circuit malfunction, DTC C146C and/or C146D is stored.

DTC No. Detection Item INF Code DTC Detection Condition Trouble Area Note
C146C Open Circuit in ABS Motor Relay Circuit 612 When operation of the ABS motor is requested, the ABS motor voltage is less than 7.6 V for 0.2 seconds or more.

  • Wire harness or connector

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

  • Brake actuator assembly

 ABS DTC
C146D Short Circuit in ABS Motor Relay Circuit 613 A short in the ABS motor relay drive circuit is detected for 4 seconds or more.

  • Wire harness or connector

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

  • Brake actuator assembly

 ABS DTC

WIRING DIAGRAM

Refer to DTC C1427.

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. CLEAR DTC


    1. Clear the DTCs.


      Chassis > ABS/VSC/TRC > Clear DTCs
      Result
      Proceed to
      NEXT

    NEXT

  2. CHECK DTC


    1. Turn the power switch off.

    2. Turn the power switch on (IG).

    3. Check if the same DTC is output.


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      Only C146C or C146D is output A
      Other than above B

    B

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS Click here

    A

  3. CHECK HARNESS AND CONNECTOR (BM TERMINAL)


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

      OK
      The connector is securely connected.

    2. Disconnect the A41 skid control ECU (brake booster with master cylinder assembly) connector.

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

      OK
      No deformation or corrosion.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A41-41 (BM) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BM CIRCUIT)

    OK

  4. CONFIRM MODEL


    1. Choose the model to be inspected.

      Result
      Result Proceed to
      for LHD A
      for RHD B

    B

    CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY) Click here

    A

  5. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY)


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

      OK
      The connector is securely connected.

    2. Disconnect the A42 brake actuator assembly connector.

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

      OK
      No deformation or corrosion.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A41-40 (+BM) - A42-13 (+BM) Always Below 1 Ω
      A41-40 (+BM) or A42-13 (+BM) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A42-1 (MGND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

  7. CLEAR DTC


    1. Reconnect the A41 skid control ECU (brake booster with master cylinder assembly) connector.

    2. Reconnect the A42 brake actuator assembly connector.

    3. Clear the DTCs.


      Chassis > ABS/VSC/TRC > Clear DTCs
      Result
      Proceed to
      NEXT

    NEXT

  8. RECONFIRM DTC


    1. Turn the power switch off.

    2. Turn the power switch on (READY).

    3. Perform a road test.

    4. Check if the same DTC is output.


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      C146C and C146D are not output A
      C146C or C146D is output B

      Tech Tips


      • If a speed signal of 20 km/h (12 mph) or more is sent to the skid control ECU (brake booster with master cylinder assembly) with the power switch on (IG) and the stop light switch assembly off, the ECU performs self diagnosis of the motor and solenoid circuits.

      • If the normal system code is output (no DTCs are output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU (brake booster with master cylinder assembly).

      • If any DTCs are output while jiggling a connector or wire harness from the skid control ECU (brake booster with master cylinder assembly), inspect and repair the connector or wire harness.

      • The DTCs were probably output due to a bad connection of the connector terminal.


    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

  9. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY)


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

      OK
      The connector is securely connected.

    2. Disconnect the A43 brake actuator assembly connector.

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

      OK
      No deformation or corrosion.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A41-40 (+BM) - A43-13 (+BM) Always Below 1 Ω
      A41-40 (+BM) or A43-13 (+BM) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A43-1 (MGND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

  11. CLEAR DTC


    1. Reconnect the A41 skid control ECU (brake booster with master cylinder assembly) connector.

    2. Reconnect the A43 brake actuator assembly connector.

    3. Clear the DTCs.


      Chassis > ABS/VSC/TRC > Clear DTCs
      Result
      Proceed to
      NEXT

    NEXT

  12. RECONFIRM DTC


    1. Turn the power switch off.

    2. Turn the power switch on (READY).

    3. Perform a road test.

    4. Check if the same DTC is output.


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      C146C and C146D are not output A
      C146C or C146D is output B

      Tech Tips


      • If a speed signal of 20 km/h (12 mph) or more is sent to the skid control ECU (brake booster with master cylinder assembly) with the power switch on (IG) and the stop light switch assembly off, the ECU performs self diagnosis of the motor and solenoid circuits.

      • If the normal system code is output (no DTCs are output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU (brake booster with master cylinder assembly).

      • If any DTCs are output while jiggling a connector or wire harness from the skid control ECU (brake booster with master cylinder assembly), inspect and repair the connector or wire harness.

      • The DTCs were probably output due to a bad connection of the connector terminal.


    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here