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Home >> Lexus >> 2002 >> SC 430 >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Abs With EBD & BA & TRAC & VSC System - Diagnosis >> DTC C1251/51: Abs Pump Motor Lock, DTC C1252/52: Brake Booster Pump Motor On Time Abnormally Long, DTC C1253/53: Brake Booster Pump Motor Circuit >> Inspection Procedure

Inspection Procedure

NOTE: Start the inspection from step 1 in case of using the LEXUS hand held tester and start from step 2 in case of not using LEXUS hand held tester.
  1. INSPECT ABS AND TRAC MOTOR RELAY OPERATION 
    1. Connect the LEXUS hand held tester to the DLC3.
    2. Turn the ignition switch ON and push the LEXUS hand held tester main switch ON.
    3. Select the ACTIVE TEST mode on the LEXUS hand held tester.
    4. Check the operation sound of the ABS and TRAC motor relays individually when operating it with the LEXUS hand held tester.

      OK: 

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

    1. NG: Go to step   6 
    2. OK: Go to next step. 
  2. INSPECT BRAKE BOOSTER PUMP MOTOR OPERATION 
    1. Disconnect the 2 connectors (B1 and B2) from the brake master cylinder.
    2. Connect the battery positive (+) lead to BM1 or BM2 terminal and battery negative (-) lead to EM1 or EM2 terminal of the brake master cylinder (pump motor) connector.

      OK: 

      The operation sound of the pump motor should be head.

      Fig 1: Inspecting Brake Booster Pump Motor Operation
      G03386386Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE BRAKE BOOSTER PUMP ASSY 
    2. OK: Go to next step. 
  3. INSPECT PRESSURE SWITCH (PH) 

    IN CASE OF USING LEXUS HAND-HELD TESTER: 

    1. Connect the LEXUS hand held tester to the DLC3.
    2. Turn the ignition switch ON and push the LEXUS hand held tester main switch ON.
    3. Select the DATALIST mode on the LEXUS 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.
      NOTE: When pressure in power supply system is released, reaction force becomes lighter.

      OK: 

      "OFF" turns to "ON". 

      NOTE: OFF: Low pressure

      ON: High pressure

    IN CASE OF NOT USING LEXUS HAND-HELD TESTER: 

    1. Disconnect the connector (B1) from the brake master cylinder.
    2. With the ignition switch OFF, depress the brake pedal more than 40 times to decrease the accumulator pressure.
      Fig 2: Measuring Resistance Between Brake Master Cylinder Connector Terminals PH & PHG
      G03386387Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      NOTE: When a pressure in power supply system is released, reaction force becomes lightly.
    3. Measure resistance between terminals PH and PHG of brake master cylinder connector.

      OK: 

      Resistance: 0.9 - 1.1 kΩ 

    4. Connect the connector (B1) to the brake master cylinder.
    5. Disconnect the connector (B1) 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 

    NOTE: After inspection, connect the connector and clear the DTC (See PRE-CHECK ).
    1. NG: REPLACE BRAKE MASTER CYLINDER SUB-ASSY 
    2. OK: Go to next step. 
  4. INSPECT PRESSURE SWITCH (PL) 

    IN CASE OF USING LEXUS HAND-HELD TESTER: 

    1. Connect the LEXUS hand held tester to the DLC3.
    2. Turn the ignition switch ON and push the LEXUS hand held tester main switch ON.
    3. Select the DATALIST mode on the LEXUS 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.
      NOTE: When a pressure in power supply system is released, reaction force becomes lightly.

      "OFF" turns to "ON". 

      NOTE: OFF: Low pressure

      ON: High pressure

    IN CASE OF NOT USING LEXUS HAND-HELD TESTER: 

    1. Disconnect the connector (B2) from the brake master cylinder.
    2. With the ignition switch OFF, depress the brake pedal more than 40 times to decrease the accumulator pressure.
      NOTE: When a pressure in power supply system is released, reaction force becomes lightly.
    3. Measure resistance between terminals PL and PLG of brake master cylinder.

      OK: 

      Resistance: 5.1 - 6.3 kΩ 

    4. Connect the connector (B2) to the brake master cylinder.
    5. Disconnect the connector (B2) 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 

      NOTE: After inspection, connect the connector and clear the DTC (See PRE-CHECK ).
      Fig 3: Measuring Resistance Between Brake Master Cylinder Connector Terminals PL & PLG
      G03386388Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE BRAKE MASTER CYLINDER SUB-ASSY 
    2. 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.
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: CHECK AND REPLACE SKID CONTROL ECU ASSY 
  6. INSPECT ABS AND TRAC MOTOR RELAY 
    1. Remove the ABS motor relay and TRAC motor relay from the engine room R/B No. 2.
    2. Check continuity between each pair of terminal of motor relay.

      OK: 

      ABS AND TRAC MOTOR RELAY TERMINALS CONTINUITY SPECIFICATIONS

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

      OK: 

      ABS AND TRAC MOTOR RELAY TERMINALS CONTINUITY SPECIFICATIONS

      Terminals 1 and 2 Continuity
      Fig 4: Checking ABS & TRAC Motor Relay Terminals Continuity
      G03386389Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE ABS MOTOR RELAY 
    2. NG: REPLACE TRACTION CONTROL RELAY 
    3. OK: Go to next step. 
  7. INSPECT ENGINE ROOM RELAY BLOCK NO. 2 
    1. Measure the voltage between terminal 2 of engine room R/B No. 2 and body ground.

      OK: 

      Voltage: 10 - 14 V 

      Fig 5: Measuring Voltage Between Terminal 2 Of Engine Room R/B No. 2 & Body Ground
      G03386390Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: CHECK AND REPLACE HARNESS AND CONNECTOR 
    2. OK: Go to next step. 
  8. CHECK HARNESS AND CONNECTOR(ENGINE ROOM R/B NO. 2 - BRAKE MASTER CYLINDER) 
    1. Check for open and short circuit in harness and connector between engine room R/B No. 2 and the terminals BM1 and BM2 of the brake master cylinder.
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. 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.
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: CHECK AND REPLACE SKID CONTROL ECU ASSY 
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