Dtc C1256 Accumulator Low Pressure

Land Cruiser URJ200 URJ202 GRJ200 VDJ200 - BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS

DESCRIPTION

INSPECTION PROCEDURE

RECONFIRM DTC

INSPECT HYDRAULIC BRAKE BOOSTER ASSEMBLY FUNCTION

READ VALUE USING GTS (ACCUMULATOR SENSOR)

RECONFIRM DTC

INSPECT BRAKE BOOSTER PUMP ASSEMBLY

DTC C1256 Accumulator Low Pressure

DESCRIPTION

Refer to DTC C1254 ().

DTC CodeDTC Detection ConditionTrouble Area
C1256The fluid pressure inside the accumulator is below the standard value.
Brake booster with accumulator pump assembly
Master cylinder solenoid (Accumulator pressure sensor)
Hydraulic brake booster assembly

INSPECTION PROCEDURE

  • NOTICE:
  • After replacing the master cylinder solenoid, perform zero point calibration ().
  • HINT:
  • When DTC C1251, C1253 or C1254 is output together with DTC C1256 inspect and repair the trouble area indicated by DTC C1251, C1253 or C1254 first.
1.RECONFIRM DTC

Clear the DTCs ().

Turn the ignition switch off.

Depress the brake pedal 20 times or more.

Turn the ignition switch to ON.

Wait for 99 seconds.

Check if the same DTC is output ().

Result
ResultProceed to
DTC is outputA
DTC is not outputB
  • HINT:
  • Excessive brake pedal operation results in abnormal accumulator pressure consumption. This is normal.
B
CHECK FOR INTERMITTENT PROBLEMS ()
A
2.INSPECT HYDRAULIC BRAKE BOOSTER ASSEMBLY FUNCTION

Inspect brake booster pump power supply system function.


Turn the ignition switch off.

Depress the brake pedal 20 times or more to release the pressure in the accumulator.

  • HINT:
  • When the pressure is released, the brake pedal stroke becomes longer.

Check that the brake fluid level is at the MAX level.

Chock the 4 wheels and release the parking brake.

Turn the ignition switch to ON and measure the brake booster pump operating time (the time from when the brake booster pump starts operating until it stops).

  • OK:
  • 20 to 80 seconds

Start the engine after the brake boost pump stops.

Check that the ABS warning light and slip indicator light are not illuminated.

Turn off the engine, and then turn the ignition switch to ON.

Check that the brake boost pump operates and then stops when the brake pedal is depressed 4 or 5 times.

Depress the brake pedal 4 or 5 times and measure the brake booster pump operating time (the time from when the brake booster pump starts operating until it stops).

  • OK:
  • 2 to 11 seconds

Check that the brake warning light illuminates and the buzzer sounds when the brake pedal is fully depressed continuously 15 to 20 times.

  • NOTICE:
  • Wait 120 seconds or more after turning the ignition switch to ON before performing this inspection.

Check brake booster operation.


Turn the ignition switch off.

Depress the brake pedal 20 times or more to release the pressure in the accumulator.

  • HINT:
  • When the pressure is released, the brake pedal stroke becomes longer.

Depress the brake pedal, start the engine, and check the change in the brake pedal height.

  • OK:
  • The brake pedal moves slightly inward.

Inspect brake master cylinder fluid pressure change (for LHD: , for RHD: ).

NG
Go to step 5
OK
3.READ VALUE USING GTS (ACCUMULATOR SENSOR)

Connect the GTS to the DLC3.

Turn the ignition switch to ON.

Turn the GTS on.

Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

ABS/VSC/TRC
Tester DisplayMeasurement Item/RangeNormal Condition Diagnostic Note
Accumulator SensorAccumulator pressure sensor reading/ Min.: 0.00 V, Max.: 5.00 V3.58 to 5 VIf the value is constant regardless of the pump operation, an accumulator pressure sensor malfunction is suspected.

Check that the accumulator output value is normal.

  • OK:
  • Accumulator pressure sensor value is normal.
Result
ResultProceed to
OKA
NG (for LHD)B
NG (for RHD)C
B
REPLACE MASTER CYLINDER SOLENOID ()
C
REPLACE MASTER CYLINDER SOLENOID ()
A
4.RECONFIRM DTC

Clear the DTCs ().

Check if the same DTC is output ().

Result
ResultProceed to
DTC is not outputA
DTC is output (for LHD)B
DTC is output (for RHD)C
B
REPLACE MASTER CYLINDER SOLENOID ()
C
REPLACE MASTER CYLINDER SOLENOID ()
A
CHECK FOR INTERMITTENT PROBLEMS ()
5.INSPECT BRAKE BOOSTER PUMP ASSEMBLY

Remove the hydraulic brake booster assembly (for LHD: , for RHD: ).

Using a screwdriver, remove the 2 screws and pull out the wire harness from the master cylinder solenoid.

Dtc C1256 Accumulator Low Pressure. BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS. Land Cruiser URJ200 URJ202 GRJ200 VDJ200

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

  • Standard Resistance:
  • Tester ConnectionConditionSpecified Condition
    Red wire terminal - Black wire terminalAlwaysBelow 2 Ω
Text in Illustration
*1Pump motor wire harness
*aRed wire
*bBlack wire

Install the pump motor wire harness to the master cylinder solenoid with the 2 screws (for LHD: , for RHD: ).

Result
ResultProceed to
OK (for LHD)A
OK (for RHD)B
NG (for LHD)C
NG (for RHD)D
B
REPLACE HYDRAULIC BRAKE BOOSTER ASSEMBLY ()
C
REPLACE BRAKE BOOSTER WITHACCUMULATOR PUMP ASSEMBLY ()
D
REPLACE BRAKE BOOSTER WITHACCUMULATOR PUMP ASSEMBLY ()
A
REPLACE HYDRAULIC BRAKE BOOSTER ASSEMBLY ()