ANTI-LOCK BRAKE SYSTEM, Diagnostic DTC:C146C

DTC Code DTC Name
C146C Open in ABS Motor Relay Circuit

DESCRIPTION

The ABS motor relay supplies power to the pump motor. While the ABS is activated, the skid control ECU turns the ABS motor relay on to operate the pump motor.

If the voltage supplied to the ABS motor relay (+BM) is too low due to low voltage from the battery or alternator, this DTC may be stored.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C146C

Open in ABS Motor Relay Circuit

Any of the following is detected:

  1. When the ABS motor relay is actuated, voltage is not supplied to the pump motor.

  2. When the ABS motor relay is not actuated, voltage in the pump motor is high.

  3. The skid control ECU judges that pump motor operation is abnormal.

  • ABS NO. 1 fuse

  • ABS motor relay circuit

  • ABS motor relay (brake actuator assembly)

WIRING DIAGRAM

C278167E01

CAUTION / NOTICE / HINT

Note:

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

Tip:

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

for C1241:Click here

for C1417:Click here

PROCEDURE

  1. PERFORM ACTIVE TEST USING GTS (ABS MOTOR RELAY)

    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Select the Active Test using the GTS.

      Click here

      Chassis > ABS/VSC/TRC > Active Test

      Tester Display

      Measurement Item

      Control Range

      Diagnostic Note

      Motor Relay

      ABS motor relay

      Relay ON/OFF

      Operating sound of motor can be heard

      Chassis > ABS/VSC/TRC > Active Test

      Tester Display

      Motor Relay

    4. Check the operating sound of the pump motor when operating it using the GTS.

    Result

    Result

    Proceed to

    Operating sound is heard.

    A

    Operating sound is not heard.

    B
    B

    CHECK HARNESS AND CONNECTOR (+BM TERMINAL)Click here

    A

  2. RECONFIRM DTC

    Tip:

    This DTC is stored when a problem is identified in the skid control ECU (brake actuator assembly).

    The ABS motor relay is in the skid control ECU (brake actuator assembly).

    Therefore, motor relay inspection and motor relay unit inspection cannot be performed. Be sure to check if the DTC is output again before replacing the skid control ECU (brake actuator assembly).

    1. Turn the ignition switch off.

    2. Clear the DTCs.

      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 40 km/h (25 mph) or more for 30 seconds or more.

    6. Check if the same DTC is output.

      Click here

      Chassis > ABS/VSC/TRC > Trouble Codes

      Result

      Result

      Proceed to

      DTC C146C is not output.

      A

      DTC C146C is output.

      B
      Tip:

      • If a speed signal of 40 km/h (25 mph) or more is received by the skid control ECU (brake actuator assembly) with the ignition switch ON, the skid control ECU (brake actuator assembly) performs self diagnosis of the motor circuit.

      • 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 hereClick hereClick here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY

    Click hereClick hereClick here

  3. CHECK HARNESS AND CONNECTOR (+BM TERMINAL)

    1. C278421C04

      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

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

    2. Disconnect the A120 skid control ECU (brake actuator assembly) connector.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A120-1 (+BM) - Body ground

      Always

      11 to 14 V

      Result

      Proceed to

      OK

      NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (+BM CIRCUIT)

    OK

  4. CHECK HARNESS AND CONNECTOR (GND2 TERMINAL)

    1. C278421C05

      *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

      A120-13 (GND2) - Body ground

      Always

      Below 1 Ω

      Result

      Proceed to

      OK

      NG
    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY

    Click hereClick hereClick here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND2 CIRCUIT)