C1256

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
NOTICE: When replacing the skid control ECU or brake actuator assembly, perform initialization of linear solenoid valve and calibration Initialization.
HINT: When C1241/41, C1252/52 or C1253/53 is output together with C1256/57, inspect and repair the trouble areas indicated by C1241/41, C1252/52 or C1253/53 first.

PROCEDURE

1. BRAKE PROBLEM CHECK
(a) Ask the customer if frequent braking is performed when the brake control warning light comes on.
OK:





HINT: This DTC is output even if the accumulator pressure drops only temporarily due to frequent braking.

B -- END
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Select the Data List mode on Techstream.

ABS / VSC / TRAC:





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




(a) Turn the power switch off.
(b) Disconnect the brake actuator connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE BRAKE ACTUATOR ASSEMBLY
OK -- Continue to next step.
4. RECONFIRM DTC
(a) Reconnect the brake actuator connector.
(b) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.
(c) Perform the road and braking test.
(d) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- REPLACE SKID CONTROL ECU
A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)