DESCRIPTION

The accumulator pressure sensor is connected to the skid control ECU in the master cylinder solenoid.

DTC Code	DTC Detection Condition	Trouble Area
C1256/56	The fluid pressure inside the accumulator is below the standard value.	Hydraulic brake booster Hydraulic brake booster pump motor Hydraulic brake booster pump motor circuit Accumulator pressure sensor

When replacing the master cylinder solenoid, perform zero point calibration .

HINT:

When C1251/51, C1253/53, or C1254/54 is output together with C1256/56, inspect and repair the trouble area indicated by C1251/51, C1253/53, or C1254/54 first.

(a) Clear the DTC .

(b) Turn the engine switch off.

(c) Depress the brake pedal more than 20 times.

(d) Turn the engine switch on (IG).

(e) Wait for 99 seconds.

(f) Check if the same DTC is output .

Result

HINT:

Excessive brake pedal operation results in abnormal accumulator pressure consumption. This is normal.

A

(a) Check the hydraulic circuit .

OK:

Hydraulic circuit is normal (No leakage).

OK

3.	READ VALUE USING TECHSTREAM (ACCUMULATOR SENSOR)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG) and turn the Techstream on.

(c) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

ABS/VSC/TRAC

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Accumulator Sensor	Accumulator pressure sensor reading/min.: 0 V, max.: 5 V	3.58 to 5 V	If the value is constant regardless of the pump operation, an accumulator pressure sensor malfunction is suspected.

(d) Check that the accumulator output value is normal.

OK:

Accumulator pressure sensor value is normal.

OK

(a) Clear the DTC .

(b) Check if the same DTC is output .

Result

A