LEMON Manuals: Even more car manuals for everyone
Home >> Lexus >> 2002 >> SC 430 >> Repair and Diagnosis (Single Page) >> Brakes >> Anti-Lock Brakes >> Abs With EBD & BA & TRAC & VSC System - Diagnosis >> DTC C1256/56: Accumulator Low Pressure >> Inspection Procedure

Inspection Procedure

  1. INSPECT BRAKE BOOSTER ACCUMULATOR ASSY 

    SST 09709-29018

    1. Turn the ignition switch OFF, and depress the brake pedal 40 times or more.
      NOTE: When a pressure in power supply system is released, reaction force becomes lightly.
    2. Install the LSPV gauge (SST) to rear brake caliper and bleed air.
    3. Depress the brake pedal with force of more than 343 N (35 kgf, 17 lbf) and turn the ignition switch ON, then check the rear brake caliper pressure when an increase of pressure changes from acutely to mildly.

      OK: 

      5,099 - 8,924 kPa (52 - 91 kgf/cm 2  , 740 - 1,294 psi) at 20°C (68°F) 

    NOTE: If the value is not within the standard, cool the engine room and check it again.
    1. NG: REPLACE BRAKE BOOSTER ACCUMULATOR ASSY 
    2. OK: Go to next step 
  2. INSPECT BRAKE BOOSTER PUMP ASSY 
    1. Disconnect the 2 connectors (B1 and B2) from the brake master cylinder.
    2. Connect 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 heard. 

      Fig 1: Inspecting Brake Booster Pump Assembly
      G03386395Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: Go to step   6 
    2. OK Go to next step 
  3. INSPECT PRESSURE SWITCH(PH) 

    SST 09709-29018

    1. Turn the ignition switch OFF, and depress the brake pedal 40 times or more.
      NOTE: When a pressure in power supply system is released, reaction force becomes lightly.
    2. Install the LSPV gauge (SST) to the rear brake caliper and bleed air.
    3. While checking the voltage between terminals PH and PHG of brake master cylinder, depress the brake pedal with force of more than 343 N (35 kgf, 77 lbf) and turn the ignition switch ON, then check the rear wheel cylinder pressure when voltage changes from 6 V to 0 V.

      12,553 - 20,104 kpa (128 - 205 kgf cm 2  ,1,820 - 2,916 psi) 

      Fig 2: Measuring Voltage Between Brake Master Cylinder Terminals PH & PHG
      G03386396Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Turn the ignition switch OFF and disconnect the connector (B1) from the brake master cylinder.
    5. While checking the resistance between terminals PH and PHG, depress the brake pedal changing the force in the range of 197 N (20 kgf, 44 lbf) to 343 N (35 kgf, 77 lbf) and check the rear wheel cylinder pressure when resistance changes from 0 kΩ to 1 kΩ between PH and PHG.

      OK: 

      11,964 - 18,240 kpa (122 - 186 kgf.cm 2  , 1,735 - 2,645 psi) 

      NOTE: After inspection, connect the connector, fill brake reservoir with brake fluid and clear the DTC (See PRE-CHECK ).
      Fig 3: Measuring Resistance Between Brake Master Cylinder Terminals PH & PHG
      G03386397Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. OK: Go to step   5 
    2. NG: Go to next step 
  4. CHECK HARNESS AND CONNECTOR(BRAKE MASTER CYLINDER - SKID CONTROL ECU) 
    1. Check for open and short circuit in harness and connector between terminal PH of the brake master cylinder and skid control ECU.
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: REPLACE BRAKE MASTER CYLINDER SUB-ASSY 
  5. INSPECT PRESSURE SWITCH (PL) 

    SST 09709-29018

    1. Turn the ignition switch OFF, and depress the brake pedal 40 times or more.
      NOTE: When a pressure in power supply system is released, reaction force becomes lightly.
    2. Install the LSPV gauge (SST) to the rear brake caliper and bleed air.
    3. Disconnect the connector (B2) from the brake master cylinder.
      Fig 4: Inspecting Pressure Switch (PL)
      G03386398Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. While checking the resistance between terminals PL and PLG of brake master cylinder, depress the brake pedal with force of more than 343 N (35 kgf, 77 lbf) and turn the ignition switch ON, then check the rear wheel cylinder pressure when the resistance changes from 5.7 kΩ. to 1.0 kΩ.

      OK: 

      9,022 - 15,102 kpa (92 - 154 kgf-cm 2  ,1,308 - 2,190 psi) 

    5. Turn the ignition switch OFF and disconnect the connector (B2) from the brake master cylinder.
    6. While checking the resistance between terminals PL and PLG of brake master cylinder, depress the brake pedal changing the force in the range of 197 N (20 kgf, 44 lbf) to 343 N (35 kgf, 77 lbf) and check the rear wheel cylinder pressure when resistance changes from 1.0 kΩ to 5.7 kΩ.

      OK: 

      8,532 - 13,337 kpa (87 - 136 kgf cm 2  , 1,237 - 1,934 psi) 

      NOTE: After inspection, connect the connector, fill brake reservoir with brake fluid and clear the DTC (See PRE-CHECK ).
    1. NG: REPLACE BRAKE MASTER CYLINDER SUB-ASSY 
    2. OK: CHECK AND REPLACE SKID CONTROL ECU ASSY 
  6. CHECK HARNESS AND CONNECTOR(BRAKE MASTER CYLINDER - BRAKE BOOSTER PUMP MOTOR) 
    1. Check for open and short circuit in harness and connector between brake master cylinder and brake booster pump motor (See PRE-CHECK ).
    1. NG: REPLACE BRAKE CONTROL WIRE 
    2. OK: Go to next step 
  7. INSPECT BRAKE BOOSTER PUMP ASSY 
    1. Inspect the brake booster pump motor operation (See MASTER CYLINDER ).
    1. NG: REPLACE BRAKE BOOSTER PUMP ASSY 
    2. OK: REPLACE BRAKE MASTER CYLINDER SUB-ASSY 
scientia non olet · About LEMON Manuals