Last Modified: 01-30-2024 6.11:8.1.0 Doc ID: RM100000001EABY
Model Year Start: 2019 Model: RAV4 Prod Date Range: [11/2018 - 02/2019]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C1256; Accumulator Low Pressure; 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]

DTC

C1256

Accumulator Low Pressure

DESCRIPTION

The accumulator pressure sensor is built into the brake actuator (brake booster with master cylinder assembly) and detects the accumulator pressure.

The skid control ECU (brake booster with master cylinder assembly) turns on the brake warning light / red (malfunction) and brake warning light / yellow (minor malfunction), and sounds the meter buzzer if it senses a decrease in the accumulator pressure.

DTC C1256 may be stored if the accumulator pressure drops due to frequent braking (this is not a malfunction).

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

Note

C1256

Accumulator Low Pressure

341

Significant drop in accumulator pressure continues.

(DTCs will be stored and the buzzer will operate when either condition is met.)

  • Accumulator pressure dropped due to frequent brake pedal operation (not a malfunction)
  • Pump motor malfunction
  • Accumulator deterioration
  • Accumulator pressure sensor (Brake booster with master cylinder assembly)
  • Supply voltage reduced

-

WIRING DIAGRAM

Refer to DTCs C1252 and C1253.

Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C1252,C1253; Brake Booster Pump Motor on Time Abnormally Long+

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the brake actuator (brake booster with master cylinder assembly), perform initialization and calibration of the linear solenoid valve.

    Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): UTILITY

  • Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

When C1202, C1241, C1252, C1253 and/or C1391 are output together with C1256, inspect and repair the trouble areas indicated by C1202, C1241, C1252, C1253 and/or C1391 first.

for C1202: Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C1202; Master Reservoir Level Malfunction

for C1241: Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C1241,C1242; Low or High Power Supply Voltage

for C1252 and C1253: Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C1252,C1253; Brake Booster Pump Motor on Time Abnormally Long

for C1391: Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): C1391; Abnormal Leak in Accumulator

PROCEDURE

1.

BRAKE PROBLEM CHECK

(a) Ask the customer if frequent braking was performed while the brake warning light / yellow (minor malfunction) was on.

Result

Proceed to

Frequent braking was not performed.

A

Frequent braking was performed.

B

HINT:

This DTC may be stored even if the accumulator pressure drops only temporarily due to frequent braking.

B

END

A

2.

INSPECT BRAKE BOOSTER PUMP ASSEMBLY

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

*a

Component without harness connected

(Brake Booster Pump Assembly)

(b) Disconnect the A49 brake booster pump assembly connectors.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2 (BM1) - 4 (GND1)

Always

Below 10 Ω

1 (BM2) - 3 (GND2)

Always

Below 10 Ω

2 (BM1) - 1 (BM2)

Always

Below 1 Ω

4 (GND1) - 3 (GND2)

Always

Below 1 Ω

NG

REPLACE BRAKE BOOSTER PUMP ASSEMBLY

OK

3.

READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)

(a) Reconnect the A49 brake booster pump assembly connectors.

(b) Connect the Techstream to the DLC3.

(c) Turn the power switch on (IG).

(d) Select the Data List on the Techstream.

Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): DTC CHECK / CLEAR

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Accumulator Sensor

Accumulator pressure sensor

Min.: 0.00 V, Max.: 5.00 V

Specified value: 2.90 to 4.20 V

When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Accumulator Sensor

(e) Depress the brake pedal 4 or 5 times to operate the pump motor.

(f) Wait for 30 seconds without depressing the brake pedal.

(g) Check that the accumulator pressure sensor output value change is within the specified range.

OK:

Accumulator pressure sensor output value change is less than 0.55 V.

OK

USE SIMULATION METHOD TO CHECK

NG

4.

PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE)

(a) Select the Active Test on the Techstream.

Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): DATA LIST / ACTIVE TEST

Chassis > ABS/VSC/TRAC > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

ECB Solenoid (SMC/SRC/SCC)

Switching solenoid valve (SMC/SRC/SCC)

Solenoid ON/OFF

  • Operation sound of solenoid (clicking sound) can be heard
  • ECB: Electronically Controlled Brake System

Chassis > ABS/VSC/TRAC > Active Test

Tester Display

ECB Solenoid (SMC/SRC/SCC)

HINT:

The Active Test can be performed when the following conditions are met.

  • ABS main relay is on.
  • Shift lever is in P.
  • Parking brake is applied.
  • Vehicle speed is 0 km/h (0 mph).

(b) Perform the Active Test of the solenoid using the Techstream.

(c) Select the Data List on the Techstream.

Click here 2019 MY RAV4 RAV4 HV [11/2018 - 02/2019]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Vacuum Brake Booster): DATA LIST / ACTIVE TEST

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Wheel Cylinder Pressure Sensor

Wheel cylinder pressure sensor

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 0.10 to 0.90 V

Reading increases when brake pedal is depressed

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Wheel Cylinder Pressure Sensor

(d) Check that the output value of the wheel cylinder pressure sensor does not increase.

OK:

The output value of the wheel cylinder pressure sensor does not increase.

HINT:

If the output value increases, there may be brake fluid leaks in the brake actuator.

OK

REPLACE BRAKE BOOSTER PUMP ASSEMBLY

NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY