Dtc C1256-09: Accumulator Low Pressure Abnormality Component Failure [11/2021 - 03/2024]: Procedure

1. Check The DTCS That Are Output.

   Chassis > Brake Booster > Trouble Codes 

   Chassis > Brake/Epb > Trouble Codes 

   Result

   Result	Proceed To
   Only Dtc C1256-09 Is Output.	A
   DTCS Other Than C1256-09 Are Output.	B

Result: 

B 

Repair Circuits Indicated By Output DTCS 

Result: 

A 

See Step  2

1. Turn The Ignition Switch Off.
2. Inspect The Brake Booster With Accumulator Pump Assembly.

   Refer To Procedure - Step 2

   Ok

   The Brake Booster With Accumulator Pump Assembly Is Normal.

   Result

   Proceed To
   Ok
   Ng

Result: 

Ng 

Replace Brake Booster With Accumulator Pump Assembly. Refer To  Removal [11/2021 - ] 

Result: 

Ok 

See Step  3

1. Reconnect The A46 Brake Booster With Accumulator Pump Assembly Connector.
2. Disconnect The A41 Brake Pedal Stroke Sensor Assembly Connector.
3. Depress The Brake Pedal Several Times To Operate The Pump Motor, Then Wait Until It Stops.
4. After The Pump Motor Stops, Wait For 30 Seconds, Then Check The Drop In The Accumulator Pressure Sensor Output Value And The State Of The Pump Motor.

   Chassis > Brake Booster > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Ecb Motor Relay	Motor Relay Operation Request	Off / On	Off: Relay Off On: Relay On	Ecb: Electronically Controlled Brake System
   Accumulator Pressure	Accumulator Pressure Output Value	Min.: 0.00 Mpa Max.: 24.48 Mpa	15.00 To 21.00 Mpa (Pressure Stable And Pump Motor Stopped)	When Brake Fluid Is Stored In The Accumulator: Accumulator Pressure Changes In Accordance With Volume Of Fluid Stored In The Accumulator

   Chassis > Brake Booster > Data List 

   Tester Display
   Ecb Motor Relay
   Accumulator Pressure

   Result

   Result	Proceed To
   The Drop In The Accumulator Pressure Sensor Output Value Is Less Than 2.50 Mpa 30 Seconds After The Pump Motor Stops, And The Pump Motor Does Not Operate Within 30 Seconds After The Pump Motor Stops.	A
   The Drop In The Accumulator Pressure Sensor Output Value Is 2.50 Mpa Or More 30 Seconds After The Pump Motor Stops, Or The Pump Motor Operates Within 30 Seconds After The Pump Motor Stops.	B

Result: 

A 

Use Simulation Method To Check. Refer To  How To Proceed With Troubleshooting [11/2021 - ] 

Result: 

B 

See Step  4

1. Turn The Ignition Switch Off.
2. Reconnect The A41 Brake Pedal Stroke Sensor Assembly Connector.
3. Perform The Active Test And Operate The Linear Solenoid (Slr) In The Brake Booster With Master Cylinder Assembly.
4. Check That The Servo Pressure Output Value Does Not Increase When Performing The Active Test.

   Chassis > Brake Booster > Active Test 

   Tester Display	Measurement Item	Control Range	Restrict Condition	Diagnostic Note
   Ecb Solenoid (Slr)	Linear Solenoid Reduction Valve (Slr)	Solenoid Start (Activate) Solenoid Slr (It Is Possible To Set The Current)	Vehicle Condition: Vehicle Stopped Shift State Is Park (P) Apply The Parking Brake	Ecb: Electronically Controlled Brake System

   Chassis > Brake Booster > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Servo Pressure	Pressure Value Of Servo	Min.: 0.00 Mpa Max.: 24.48 Mpa	Brake Pedal Released: 0.00 To 1.53 Mpa	Brake Pedal Is Being Depressed: Changes In Proportion To The Depression Force Of The Brake Pedal

   Chassis > Brake Booster > Active Test 

   Active Test Display
   Ecb Solenoid (Slr)

   Data List Display
   Servo Pressure

   Ok

   The Servo Pressure Output Value Does Not Increase When Performing The Active Test.

   Hint: 

   • If The Servo Pressure Output Value Increases, An Internal Brake Fluid Leak In The Brake Booster With Master Cylinder Assembly Is Suspected.
   • Perform The Active Test With The Current Set To Maximum.

   Result

   Result	Proceed To
   The Servo Pressure Output Value Increases.	A
   The Servo Pressure Output Value Does Not Increase.	B

Result: 

A 

Replace Brake Booster With Master Cylinder Assembly. Refer To  Removal [11/2021 - ] 

Result: 

B 

Replace Brake Booster With Master Cylinder Assembly And Brake Booster With Accumulator Pump Assembly 

For Brake Booster With Master Cylinder Assembly: Refer To Removal [11/2021 - ]

For Brake Booster With Accumulator Pump Assembly: Refer To Removal [11/2021 - ]