Electronically Controlled Brake System

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1256/57: Accumulator Low Pressure

DTC C1256/57 - Accumulator Low Pressure

DESCRIPTION

The accumulator pressure sensor is built into the actuator and detects the accumulator pressure.
The skid control ECU turns on the brake control warning light and sounds the skid control buzzer if it senses a decrease in the accumulator pressure.






WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE:
When replacing the skid control ECU or brake actuator assembly, perform initialization of linear solenoid valve and calibration Programming and Relearning.
HINT:
- When C1241/41, C1252/52 or C1253/53 are output together with C1256/57, inspect and repair the trouble areas indicated by C1241/41, C1252/52 or C1253/53 first.
- DTCs may be output if the accumulator pressure drops due to frequent braking (this is not a malfunction).

PROCEDURE

1. INSPECT BRAKE ACTUATOR ASSEMBLY




(a) Disconnect the brake actuator assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.

2. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Select the Data List mode on the Techstream.

ABS / VSC / TRAC:





(d) Depress the brake pedal 4 or 5 times to operate the pump motor, and check the output value on the Techstream with the motor stopped (not braking).
OK:
ACC pressure sensor's output voltage does not drop.
NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.

3. RECONFIRM DTC
(a) Clear the DTC Electronically Controlled Brake System.
(b) Turn the engine switch on (IG).
(c) Check if the same DTC is recorded Electronically Controlled Brake System.
HINT: Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result:






B -- REPLACE SKID CONTROL ECU
A -- END