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Home >> Lexus >> 2004 >> GX 470 >> Repair and Diagnosis >> Brakes >> Anti-Lock Brakes >> Abs With EBD & BA & TRAC & VSC System - Diagnosis >> DTC C1251/51, C1252/52, C1253/53: Pump Motor Is Locked/Open Circuit In Pump Motor Ground; Brake Booster Pump Motor On Time Abnormally Long; Brake Booster Pump Motor Circuit >> Inspection Procedure

Inspection Procedure

HINT:

Start the inspection from step  1 in case of using the hand-held tester and start from step  2 in case of no using hand-held tester.

  1. INSPECT ABS AND TRAC MOTOR RELAY OPERATION 
    1. Connect the hand-held tester to the DLC3.
    2. Turn the ignition switch ON and push the hand-held tester main switch ON.
    3. Select the ACTIVE TEST mode on the hand-held tester.
    4. Check the operation sound of the ABS and TRAC MTR relays individually when operating it with the hand-held tester.

      OK: 

      The operation sound of the ABS and TRAC MTR relay should be heard. 

    NG : Go to step   6 

    OK : GO TO NEXT STEP 

  2. INSPECT BRAKE BOOSTER PUMP MOTOR OPERATION 
    1. Disconnect the 2 connectors (A4 and A5) from the brake master cylinder.
    2. Connect the battery positive (+) lead to BM1 or BM2 terminal and battery negative (-) lead to GND1 or GND2 terminal of the brake master cylinder (pump motor) connector.

      OK: 

      The operation sound of the pump motor should be head. 

    NG : REPLACE BRAKE BOOSTER PUMP ASSY 

    Fig 1: Inspecting Brake Booster Pump Motor Operation
    G04354815Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : GO TO NEXT STEP 

  3. INSPECT PRESSURE SWITCH (PH) 

    IN CASE OF USING HAND-HELD TESTER: 

    1. Connect the hand-held tester to the DLC3.
    2. Turn the ignition switch ON and push the hand-held tester main switch ON.
    3. Select the DATA LIST mode on the hand-held tester.
    4. Depress the brake pedal more than 40 times with the ignition switch OFF then turn the ignition switch ON and check the pressure switch (PH) condition.

      HINT:

      When a pressure in power supply system is released, reaction force becomes lightly.

      OK: 

      "OFF" turns to "ON". 

    HINT:

    OFF: Low pressure

    ON: High pressure

    IN CASE OF NOT USING HAND-HELD TESTER: 

    1. Disconnect the connector (A4) from the brake master cylinder.
    2. With the ignition switch OFF, depress the brake pedal more than 40 times to decrease the accumulator pressure.

      HINT:

      When a pressure in power supply system is released, reaction force becomes lightly.

      Fig 2: Inspecting Pressure Switch (PH)
      G04354816Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Measure resistance between terminals PH and PHG of brake master cylinder connector.

      OK: 

      Resistance: 0.9 - 1.1 kΩ 

    4. Connect the connector (A4) to the brake master cylinder.
    5. Disconnect the connector (A4) after ignition switch has been ON and the pump motor has stopped.
    6. Measure resistance between terminals PH and PHG of brake master cylinder.

      OK: 

      Resistance: 0 Ω 

      HINT:

      After inspection, connect the connector and clear the DTC (See PRE-CHECK  ).

    NG : REPLACE BRAKE MASTER CYLINDER 

    OK : GO TO NEXT STEP 

  4. INSPECT PRESSURE SWITCH(PL) 

    IN CASE OF USING HAND-HELD TESTER: 

    1. Connect the hand-held tester to the DLC3.
    2. Turn the ignition switch ON and push the hand-held tester main switch ON.
    3. Select the DATA LIST mode on the hand-held tester.
    4. Depress the brake pedal more than 40 times with the ignition switch OFF then turn the ignition switch ON and check the pressure switch (PL) condition.

      HINT:

      When a pressure in power supply system is released, reaction force becomes lightly.

      OK: 

      "OFF" turns to "ON". 

    HINT:

    OFF: Low pressure

    ON: High pressure

    IN CASE OF NOT USING HAND-HELD TESTER: 

    1. Disconnect the connector (A5) from the brake master cylinder.
    2. With the ignition switch OFF, depress the brake pedal more than 40 times to decrease the accumulator pressure.

      HINT:

      When a pressure in power supply system is released, reaction force becomes lightly.

      Fig 3: Inspecting Pressure Switch (PL)
      G04354817Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Measure resistance between terminals PL and PLG brake master cylinder.

      OK: 

      Resistance: 5.1 - 6.3 kΩ 

    4. Connect the connector (A5) to the brake master cylinder.
    5. Disconnect the connector (A5) after ignition switch has been ON and the pump motor has stopped.
    6. Measure resistance between terminals PL and PLG of brake master cylinder.

      OK: 

      Resistance: 1.0 kΩ 

      HINT:

      After inspection, connect the connector and clear the DTC (See PRE-CHECK  ).

    NG : REPLACE BRAKE MASTER CYLINDER 

    OK : GO TO NEXT STEP 

  5. CHECK HARNESS AND CONNECTOR(BRAKE MASTER CYLINDER - SKID CONTROL ECU) 
    1. Check for open and short circuit in harness and connector between pressure switch circuit of the brake master cylinder and skid control ECU (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK : CHECK AND REPLACE SKID CONTROL ECU ASSY 

  6. INSPECT ABS AND TRAC MOTOR RELAY 
    1. Remove the ABS MTR relay and TRAC MTR relay from the engine room R/B.
    2. Check continuity between each pair of terminal of motor relay.

      OK: 

      CONTINUITY TABLE

      Terminals 3 and 4 Continuity (Reference value (1))
      Terminals 1 and 2 Open
      (1) ABS MTR relay: 62 Ω TRAC MTR relay: 54 Ω
    3. Apply battery positive voltage between terminals 3 and 4.
    4. Check continuity between terminals.

      OK: 

      CONTINUITY TABLE

      Terminals 1 and 2 Continuity

    NG : REPLACE ABS MOTOR RELAY 

    NG : REPLACE TRACTION CONTROL RELAY 

    Fig 4: Inspecting ABS & TRAC Motor Relay
    G04354818Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : GO TO NEXT STEP 

  7. INSPECT ENGINE ROOM RELAY BLOCK 
    1. Measure the voltage between terminal 1 of engine room R/B and body ground.

      OK: 

      Voltage: 10 - 14 V 

      Fig 5: Inspecting Engine Room Relay Block
      G04354819Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG : CHECK AND REPLACE HARNESS AND CONNECTOR 

    OK : GO TO NEXT STEP 

  8. CHECK HARNESS AND CONNECTOR(ENGINE ROOM R/B - BRAKE MASTER CYLINDER) 
    1. Check for open and short circuit in harness and connector between engine room R/B and the terminals BM1 and BM2 of the brake master cylinder (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK : GO TO NEXT STEP 

  9. CHECK HARNESS AND CONNECTOR(BRAKE MASTER CYLINDER - SKID CONTROL ECU) 
    1. Check for open and short circuit in harness and connector between each terminals MTT, MT+ and MT- of the brake master cylinder and the same one of the skid control ECU (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK : CHECK AND REPLACE SKID CONTROL ECU ASSY 

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