ELECTRONICALLY CONTROLLED BRAKE 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

These DTCs are stored when a problem is identified in the skid control ECU (brake actuator assembly).

The ABS motor relay supplies power to the pump motor. While the ABS is activated, the ECU turns the ABS motor relay on and operates the pump motor.

If the voltage supplied to the motor relay (BM) is below the DTC detection threshold due to low voltage from the battery or alternator, these DTCs may be stored.

DTC No. Detection Item DTC Detection Condition Trouble Area Note
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.

  • VSC 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.

  • VSC 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:


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

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

  • Brake actuator assembly (Motor relay)

  • Wire harness or connector

 -
C146D DTC Detection Conditions
Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition - - -
Malfunction Status Overcurrent in motor relay and motor fail-safe relay continues ○ -
Motor relay gate voltage malfunction continues - ○
Detection Time 0.05 seconds or more. 0.12 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

B006E7FE34

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 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 engine switch off.

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

    3. Disconnect the A9 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
      A9-13 (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. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A9-1 (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 A9 skid control ECU (brake actuator assembly) connector.

    2. Clear the DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    3. Turn the engine switch off.

    4. Start the engine.

    5. Perform a road test.

    6. Check if the same DTC is output.

      Click here


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

      Tech Tips


      • If a speed signal of 6 km/h (4 mph) or more is sent to the skid control ECU (brake actuator assembly) with the engine 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 actuator assembly).

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

      • If no DTCs were output when reconfirming DTCs, checking for intermittent problems is necessary because it is suspected that the original DTCs were stored due to the poor connection of a connector terminal.


    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here