Vehicle Stability Control System

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: C1256/56: Accumulator Low Pressure

DTC C1256/56 - Accumulator Low Pressure

DESCRIPTION





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT BRAKE BOOSTER ACCUMULATOR ASSEMBLY
(a) Turn the ignition switch OFF, and depress the brake pedal 40 times or more.
HINT: When pressure in the power supply system is released, the brake pedal becomes easier to depress.
(b) Install the LSPV gauge (SST) to the rear brake caliper and bleed air.
SST: 09709-29018
(c) Depress the brake pedal with a force of more than 343 N (35 kgf, 77 lbf) and turn the ignition switch ON. Then check the rear brake caliper pressure when the increase in pressure changes from a sudden to a gradual increase.
Standard pressure:
5,099 to 8,924 kPa (52 to 91 kgf/cm2, 740 to 1,294 psi) at 20°C (68°F)
HINT: If the value is not within the standard, cool the engine room and check it again.

NG -- REPLACE BRAKE BOOSTER ACCUMULATOR ASSEMBLY
OK -- Continue to next step.
2. CHECK BRAKE BOOSTER PUMP ASSEMBLY




(a) Disconnect the B1 and B2 actuator connectors.
(b) Connect the battery positive (+) leads to terminals 2 (BM1) and 3 (BM2) of the actuator (pump motor) connector and battery negative (-) leads to terminals 1 (EM1) and 6 (EM2).
OK:
Operation sound of pump motor can be heard.
NG -- CHECK BRAKE CONTROL WIRE (BRAKE ACTUATOR - BRAKE BOOSTER PUMP MOTOR)
OK -- Continue to next step.
3. CHECK BRAKE BOOSTER PRESSURE SWITCH (PH)




(a) Turn the ignition switch OFF, and depress the brake pedal 40 times or more.
HINT: When pressure in the power supply system is released, the brake pedal becomes easier to depress.
(b) Install the LSPV gauge (SST) to the rear brake caliper and bleed air.
SST: 09709-29018
(c) While checking the voltage between terminals PH and PHG of the brake master cylinder, depress the brake pedal with a force of more than 343 N (35 kgf, 77 lbf) and turn the ignition switch ON. Then check the rear wheel cylinder pressure when voltage changes from 6 V to 0 V.
Standard pressure:
12,553 to 20,104 kPa (128 to 205 kgf/cm2, 1,820 to 2,916 psi)




(d) Turn the ignition switch OFF and disconnect the B1 connector from the brake actuator.
(e) While checking the resistance between terminals PH and PHG, depress the brake pedal, changing the force in the range of 197 N (20 kgf, 44 lbf) to 343 N (35 kgf, 77 lbf), and check the rear wheel cylinder pressure when the resistance between terminals PH and PHG changes from 0 kOhms to 1 kOhms.
Standard pressure:
11,964 to 18,240 kPa (122 to 186 kgf/cm2, 1,735 to 2,645 psi)
HINT: After the inspection, connect the connector, fill the brake reservoir with brake fluid and clear the DTC Reading and Clearing Diagnostic Trouble Codes.

OK -- CHECK BRAKE BOOSTER PRESSURE SWITCH (PL)
NG -- Continue to next step.
4. CHECK WIRE HARNESS (BRAKE ACTUATOR - SKID CONTROL ECU AND BODY GROUND)




(a) Disconnect the B1 and B2 actuator connectors.
(b) Disconnect the S5 and S8 ECU connectors.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE BRAKE ACTUATOR
5. CHECK BRAKE BOOSTER PRESSURE SWITCH (PL)




(a) Turn the ignition switch OFF, and depress the brake pedal 40 times or more.
HINT: When pressure in the power supply system is released, the brake pedal becomes easier to depress.
(b) Install the LSPV gauge (SST) to the rear brake caliper and bleed air.
SST: 09709-29018
(c) Disconnect the B2 connector from the brake actuator.
(d) While checking the resistance between terminals PL and PLG of the brake actuator, depress the brake pedal with a force of more than 343 N (35 kgf, 77 lbf) and turn the ignition switch ON. Then check the rear wheel cylinder pressure when the resistance changes from 5.7 kOhms to 1.0 kOhms.
Standard pressure:
9,022 to 15,102 kPa (92 to 154 kgf/cm2, 1,308 to 2,190 psi)
(e) Turn the ignition switch OFF and disconnect the B2 connector from the brake actuator.
(f) While checking the resistance between terminals PL and PLG of the brake actuator, depress the brake pedal, changing the force in the range of 197 N (20 kgf, 44 lbf) to 343 N (35 kgf, 77 lbf), and check the rear wheel cylinder pressure when the resistance between terminals PL and PLG changes from 1.0 kOhms to 5.7 kOhms.
Standard pressure:
8,532 to 13,337 kPa (87 to 136 kgf/cm2, 1,237 to 1,934 psi)
HINT: After the inspection, connect the connector, fill the brake reservoir with brake fluid and clear the DTC Reading and Clearing Diagnostic Trouble Codes.

NG -- REPLACE BRAKE ACTUATOR
OK -- REPLACE SKID CONTROL ECU
6. CHECK BRAKE CONTROL WIRE (BRAKE ACTUATOR - BRAKE BOOSTER PUMP MOTOR)
(a) Remove the brake control wire.
(b) Measure the resistance of the brake control wire.
Standard resistance:
Below 1 Ohms
NG -- REPLACE BRAKE CONTROL WIRE
OK -- Continue to next step.
7. CHECK BRAKE BOOSTER PUMP ASSEMBLY
(a) Check the brake booster pump motor operation.
OK:
Operation sound of motor can be heard.
NG -- REPLACE BRAKE BOOSTER PUMP ASSEMBLY
OK -- REPLACE BRAKE ACTUATOR