ANTI-LOCK BRAKE SYSTEM, Diagnostic DTC:C1251/51

DTC Code DTC Name
C1251/51 Open in Pump Motor Circuit

DESCRIPTION

The motor relay (semiconductor relay) is housed in the brake actuator assembly and drives the pump motor based on a signal from the skid control ECU.

DTC No. DTC Detection Condition Trouble Area
C1251/51

When either of the following is detected during the initial check:


  • The pump motor does not rotate normally.


  • Open in the pump motor circuit continues for 2 seconds or more.

  • Brake actuator pump motor circuit

  • Brake actuator assembly

WIRING DIAGRAM

Refer to DTC C0273/13 and C0274/14 Click here.

INSPECTION PROCEDURE

Tech Tips

After step 1 is complete, start the inspection from step 2 when using the intelligent tester, and from step 3 when not using the intelligent tester.

PROCEDURE


  1. INSPECT SKID CONTROL ECU (GND TERMINAL CONTINUITY)


    1. A003DPCE29

      Disconnect the skid control ECU connector.

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

      Standard resistance
      Tester Connection Specified Condition
      B19-2 (GND) - Body ground Below 1 Ω
      B19-24 (GND) - Body ground Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

  2. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (ABS MOTOR RELAY)


    1. Reconnect the skid control ECU connector.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to the ON position and turn the intelligent tester main switch on.

    4. Start the engine.

    5. Select the ACTIVE TEST mode on the intelligent tester.

      ABS:
      Item (Display) Vehicle Condition / Test Details Diagnostic Note
      ABS Motor Relay Turns ABS motor relay ON / OFF Operating sound of motor is heard

    6. Check operating sound of the ABS motor when operating it with the intelligent tester.

      OK
      The operating sound of the ABS motor is heard.

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY

    OK

  3. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Start the engine.

    3. Drive the vehicle at the speed of 4 mph (6 km/h) or more.

    4. Check that the same DTC is recorded Click here.

      Tech Tips


      • Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

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

      Result
      Condition Proceed to
      DTC (C1251/51) is output A
      DTC (C1251/51) not output B

      Tech Tips


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

      • If the normal system code is output, slightly jiggle the connectors, wire harnesses, and fuses of the brake actuator assembly. Make sure that no DTCs are output.

      • These DTCs may be stored due to a malfunction in the connector terminal connection, etc.


    B

    END

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY