Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Abnormal Leak in Accumulator (C1391)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System(for Hv Model) / Abnormal Leak in Accumulator (C1391)

DESCRIPTION

This DTC is stored if internal or external brake fluid leaks are detected due to improper sealing in the brake actuator (brake booster with master cylinder assembly) or brake booster pump assembly. Internal leaks are suspected if the pump motor operates frequently without braking.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

MIL

Note

C1391

Abnormal Leak in Accumulator

351

Either of the following is detected:

  • When the brake pedal is not depressed and the pump motor is operating, the accumulator pressure sensor value does not increase a certain number of times.
  • When the brake pedal is not depressed and the pump motor is not operating, the accumulator pressure sensor decrease rate exceeds a certain threshold a certain number of times.
  • Brake fluid leaks
  • Brake actuator (brake booster with master cylinder assembly)

    (Malfunctioning internal seal etc.)

  • Brake booster pump assembly

    (Accumulator internal gas pressure decrease, etc.)

Does not come on

Electronically controlled brake system DTC
DTC Detection Conditions: C1391 INF Code: 351
 

Vehicle Condition

Pattern 1

Pattern 2

Diagnosis Condition

Brake pedal not depressed and pump motor operating.

○

-

Brake pedal not depressed and pump motor not operating.

-

○

Malfunction Status

The accumulator pressure sensor value does not increase a certain number of times.

○

-

The accumulator pressure sensor decrease rate exceeds a certain threshold a certain number of times.

-

○

Detection Time

-

-

Number of Trips

1 trip

1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

CAUTION / NOTICE / HINT

NOTICE:

After replacing the brake actuator (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".

Click here

PROCEDURE

1.

READ VALUE USING TECHSTREAM (SERVO PRESSURE)

(a) Select the Active Test on the Techstream.

Click here

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

(b) Perform the Active Test and operate the linear solenoid (SLR) in the brake actuator (brake booster with master cylinder assembly).

(c) 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

Proceed to

The servo pressure output value increases.

A

The servo pressure output value does not increase.

B
A

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

B

2.

CHECK OPERATING TIME OF PUMP MOTOR

(a) Turn the power switch on (READY).

(b) Select the Data List on the Techstream.

Click here

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

(c) 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.

NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

OK

3.

CHECK FOR FLUID LEAK

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

Click here

OK:

There are no brake fluid leaks.

OK

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

NG

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