VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C142B, C146C, C146D

DTC Code DTC Name
C142B Motor Power Supply Voltage Circuit
C146C Open in ABS Motor Relay Circuit
C146D Short in ABS Motor Relay Circuit

DESCRIPTION

The motor relay and motor fail-safe relay are built into the brake actuator assembly.

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

When a motor system DTC is stored, the motor fail-safe relay cuts the power source supply to the motor relay for fail-safe operation.

These DTCs may be stored when the voltage to the motor relay power source (BM terminal) is lower than the DTC detection condition due to low output from the battery or alternator.

DTC No. Detection Item DTC Detection Condition Trouble Area
C142B Motor Power Supply Voltage Circuit When voltage at +BS terminal is 9.5 V or higher, open in BM terminal continues for 1 second or more.

  • ABS NO. 1 fuse

  • Skid Control ECU (Brake actuator assembly)

  • Wire harness or connector
C146C Open in ABS Motor Relay Circuit When voltage at +BS terminal is 9.5 V or higher and motor relay ON while control operates, relay contact OFF condition continues for 0.12 seconds or more.

  • ABS NO. 1 fuse

  • Brake actuator assembly (Motor relay)

  • Wire harness or connector
C146D Short in ABS Motor Relay Circuit

Either of the following is detected:


  1. Overcurrent in motor relay and motor fail-safe relay continues for 0.05 seconds or more.

  2. Motor relay gate voltage malfunction continues for 0.12 seconds or more.

  • Brake actuator assembly (Motor relay)

  • Wire harness or connector

WIRING DIAGRAM

B003PWRE07

CAUTION / NOTICE / HINT

Note


  • When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information.

    Click here

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

Tech Tips

When C1241 and/or C1417 is output together with C142B, C146C and/or C146D inspect and repair the trouble areas indicated by C1241 and/or C1417 first.

for C1241: Click here

for C1417: Click here

PROCEDURE


  1. CHECK TERMINAL VOLTAGE (BM TERMINAL)


    1. Turn the ignition switch off.

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

    3. B003PGQC68
      *a

      Front view of wire harness connector

      (to Skid Control ECU [Brake Actuator Assembly])

      Disconnect the A4 skid control ECU (brake actuator assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A4-13 (BM) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BM CIRCUIT)

    OK

  2. CHECK HARNESS AND CONNECTOR (GND2 TERMINAL)


    1. B003PGQC67
      *a

      Front view of wire harness connector

      (to Skid Control ECU [Brake Actuator Assembly])

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A4-1 (GND2) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND2 CIRCUIT)

    OK

  3. RECONFIRM DTC

    Tech Tips

    These codes are stored when a problem is identified in the skid control ECU (brake actuator assembly). The motor relay is in the skid control ECU (brake actuator assembly). Therefore, motor relay inspections and motor relay unit inspections cannot be performed. Be sure to check if any DTCs are output before replacing the brake actuator assembly.


    1. Reconnect the A4 skid control ECU (brake actuator assembly) connector.

    2. Clear the DTC.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Drive the vehicle at a speed of 20 km/h (12 mph) or more for 30 seconds or more.

    6. Check if the same DTC is recorded.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Proceed to
      DTCs C142B, C146C and C146D are not output
      DTCs C142B, C146C and/or C146D are output

      Tech Tips


      • If a speed signal of 6 km/h (4 mph) or more is input to the skid control ECU (brake actuator assembly), with the ignition switch to ON and the stop light switch off, the ECU performs self diagnosis of the motor and solenoid circuits.

      • If the normal system code is output (the trouble code is not output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU (brake actuator assembly). Make sure that no DTCs are output.

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

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


    DTCs C142B, C146C and C146D are not output

    USE SIMULATION METHOD TO CHECK Click here

    DTCs C142B, C146C and/or C146D are output

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here