DTC C1391: Abnormal Leak in Accumulator [10/2018 - ]: Procedure

1. Select the Active Test on the Techstream.

   Refer to DATA LIST / ACTIVE TEST [10/2018 - ]

   Chassis > ABS/VSC/TRAC > Active Test 

   Tester Display	Measurement Item	Control Range	Diagnostic Note
   ECB Solenoid (SLR)	Linear solenoid reduction valve (SLR)	Solenoid ON/OFF	ECB: Electronically Controlled Brake System

   Chassis > ABS/VSC/TRAC > 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 2.10 MPa	Brake pedal is being depressed: Changes in proportion to the depression force of the brake pedal

   Chassis > ABS/VSC/TRAC > Active Test 

   Active Test Display
   ECB Solenoid (SLR)

   Data List Display
   Servo Pressure

2. Perform the Active Test and operate the linear solenoid (SLR) in the brake actuator (brake booster with master cylinder assembly).
3. Check that the servo pressure output value does not increase when performing the Active Test.

   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 actuator (brake booster with master cylinder assembly) is suspected.

   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 [10/2018 - 07/2022]  , or refer to  REMOVAL [07/2022 - ] 

Result: 

B 

See step  2

1. Turn the power switch on (READY).
2. Select the Data List on the Techstream.

   Refer to DATA LIST / ACTIVE TEST [10/2018 - ]

   Chassis > ABS/VSC/TRAC > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   MT Voltage Value	MT voltage value	Min.: 0.00 V, Max.: 20.00 V	Pump motor off: 0.00 V Pump motor on: 12.00 V	-

   Chassis > ABS/VSC/TRAC > Data List 

   Tester Display
   MT Voltage Value

3. With the power switch on (READY), check the operation of the pump motor.

   OK

   The pump motor operates once or more within 20 seconds or operates for 10 seconds or more each time.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022]  , or refer to  REMOVAL [07/2022 - ] 

Result: 

OK 

See step  3

1. Check for brake fluid leaks in the line from the brake booster pump assembly to the brake booster with master cylinder assembly.

   Refer to PROCEDURE - Step 2

   OK

   There are no brake fluid leaks.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY AND BRAKE BOOSTER PUMP ASSEMBLY 

for the brake booster with master cylinder assembly: Refer to REMOVAL [10/2018 - 07/2022] , or refer to REMOVAL [07/2022 - ]

for the brake booster pump assembly: Refer to REMOVAL [10/2018 - 07/2022] , or refer to REMOVAL [07/2022 - ]

Result: 

NG 

REPAIR MALFUNCTIONING PART