Diagnostic trouble code C1256 Land Cruiser

DESCRIPTION

INSPECTION PROCEDURE

RECONFIRM DTC

CHECK HYDRAULIC CIRCUIT

READ VALUE USING INTELLIGENT TESTER (ACCUMULATOR SENSOR)

RECONFIRM DTC

DTC C1256/56 Accumulator Low Pressure

Description

The accumulator pressure sensor is connected to the skid control ECU in the master cylinder solenoid.

Diagnostic trouble code C1256 Land Cruiser
DTC Code DTC Detection Condition Trouble Area
C1256/56 The fluid pressure inside the accumulator is below the standard value.
  1. Hydraulic brake booster
  2. Hydraulic brake booster pump motor
  3. Hydraulic brake booster pump motor circuit
  4. Accumulator pressure sensor

Inspection procedure

NOTICE:

When replacing the master cylinder solenoid, perform zero point calibration .

HINT:

When C1251/51, C1253/53, or C1254/54 is output together with C1256/56, inspect and repair the trouble area indicated by C1251/51, C1253/53, or C1254/54 first.

1.RECONFIRM DTC

  1. Clear the DTC .

  1. Turn the ignition switch off.

  1. Depress the brake pedal more than 20 times.

  1. Turn the ignition switch to ON.

  1. Wait for 99 seconds.

  1. Check if the same DTC is output .

Result
Result Proceed to
DTC is output A
DTC is not output B

HINT:

Excessive brake pedal operation results in abnormal accumulator pressure consumption. This is normal.

  B  
USE SIMULATION METHOD TO CHECK
 
A  
   

2.CHECK HYDRAULIC CIRCUIT

  1. Check the hydraulic circuit .

    OK:

    Hydraulic circuit is normal (No leakage).

  NG  
REPAIR HYDRAULIC CIRCUIT
 
OK  
   

3.READ VALUE USING INTELLIGENT TESTER (ACCUMULATOR SENSOR)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON and turn the intelligent tester on.

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

ABS/VSC/TRC
Tester Display Measurement Item/Range Normal Condition Diagnostic Note
Accumulator Sensor Accumulator pressure sensor reading / min.: 0.00 V, max.: 5.00 V 3.58 to 5 V If the value is constant regardless of the pump operation, an accumulator pressure sensor malfunction is suspected.

  1. Check that the accumulator output value is normal.

    OK:

    Accumulator pressure sensor value is normal.

Result
Result Proceed to
OK A
NG LHD B
RHD C
  B  
REPLACE MASTER CYLINDER SOLENOID
 
  C  
REPLACE MASTER CYLINDER SOLENOID
 
A  
   

4.RECONFIRM DTC

  1. Clear the DTC .

  1. Check if the same DTC is output .

Result
Result Proceed to
DTC is not output A
DTC is output LHD B
RHD C
  B  
REPLACE MASTER CYLINDER SOLENOID
 
  C  
REPLACE MASTER CYLINDER SOLENOID
 
A  
   
USE SIMULATION METHOD TO CHECK