C1252
C1252, C1253Description
The brake ECU detects decreases in the accumulator pressure according to the data from the accumulator pressure sensor, and then starts and stops the pump motor by operating the motor relay.
The brake ECU usually drives the ABS motor relay No.1 for Electronically Controlled Brake control, and the ABS motor relay No.2 for ABS control. If either of them is malfunctioning, the other will substitute.
DTC Logic:
Diagnosis Procedure
CAUTION:
When replacing the brake ECU or brake actuator assembly, perform initialization of linear solenoid valve and calibration.
1.INSPECT ABS MTR FUSE
1. Remove the fusible link from the engine room R/B.
2. Check if the fusible link is melted.
NOTE:
The fusible link is melted.
3. Install the fusible link to the engine room R/B with the bolt.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Replace fusible link (ABS MTR FUSE).
2.PERFORM ACTIVE TEST BY CONSULT-III (ABS MOTOR RELAY)
1. Connect the CONSULT-III.
2. Turn the ignition switch ON.
3. Select the "ACTIVE TEST" on the CONSULT-III.
4. Check the operation sound of the ABS motor relay and motor when operating it with the CONSULT-III.
NOTE:
The operation sound of the ABS motor relay and motor should be heard.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 7.
3.INSPECT BRAKE ACTUATOR ASSEMBLY
1. Turn the ignition switch OFF.
2. Disconnect the brake actuator connector.
3. Measure the resistance according to the value(s) in the table below.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace brake actuator assembly.
4.CHECK HARNESS AND CONNECTOR (BRAKE ECU - BRAKE ACTUATOR)
1. Disconnect the brake ECU connector.
2. Measure the resistance according to the value(s) in the table below.
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace harness or connector.
5.READ VALUE OF CONSULT-III (ACCUMULATOR PRESSURE SENSOR)
1. Reconnect the brake ECU connector and the brake actuator connector.
2. Connect the CONSULT-III.
3. Turn the ignition switch ON.
4. Select the "DATA MONITOR" on the CONSULT-III.
ABS/VDC:
5. Depress the brake pedal 4 or 5 times to operate the pump motor, and check the output value on the CONSULT-III with the motor stopped (not braking).
NOTE:
Accumulator pressure sensor voltage does not drop.
Is the inspection result normal?
YES >> GO TO 6.
NO >> Replace brake actuator assembly.
6.RECONFIRM DTC
1. Turn the ignition switch OFF.
2. Clear the DTC.
3. Turn the ignition switch ON.
4. Check if the same DTC is recorded.
Result:
A >> Check for intermittent problems (symptom simulation).
B >> Replace brake ECU.
7.INSPECT ABS MOTOR RELAY (ABS MOTOR RELAY NO.1 AND NO.2)
1. Turn the ignition switch OFF.
2. Remove the ABS motor relay No.1 and the ABS motor relay No.2.
3. Measure the resistance according to the value(s) in the table below.
Is the inspection result normal?
YES >> GO TO 8.
NO >> Replace ABS motor relay (ABS motor relay No.1 or No.2).
8.INSPECT ENGINE ROOM NO.3 RELAY BLOCK (POWER SOURCE TERMINAL)
Measure the voltage according to the value(s) in the table below.
Is the inspection result normal?
YES >> GO TO 9.
NO >> Repair or replace harness or connector (power source circuit).
9.CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR - ENGINE ROOM NO.3 RELAY BLOCK)
1. Disconnect the brake actuator connector.
2. Measure the resistance according to the value(s) in the table below.
Is the inspection result normal?
YES >> GO TO 10.
NO >> Repair or replace harness or connector.
10.CHECK HARNESS OR CONNECTOR (BRAKE ECU - ENGINE ROOM NO.3 RELAY BLOCK)
1. Disconnect the brake ECU connectors.
2. Measure the resistance according to the value(s) in the table below.
Is the inspection result normal?
YES >> GO TO 11.
NO >> Repair or replace harness or connector.
11.RECONFIRM DTC
1. Clear the DTC.
2. Turn the ignition switch ON.
3. Check if the same DTC is recorded.
NOTE:
Reinstall the relays, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.
Result:
A >> Check for intermittent problems (symptom simulation).
B >> Replace brake ECU.
Special Repair Requirement
1.ZERO ADJUSTMENT FOR EACH SENSOR AND OFFSET LEANING FOR LINEAR SOLENOID VALVE
After erasing brake ECU memories, perform zero adjustment of following sensors and initialization of linear solenoid valve.
^ Steering angle sensor: BRC-9, "PERFORM ZERO POINT OF STEERING ANGLE SENSOR: Description". Testing and Inspection
^ Yaw rate/side/decel G sensor: BRC-8, "PERFORM ZERO POINT OF YAW RATE/SIDE/DECEL G SENSOR: Description". Testing and Inspection
^ Brake stroke sensor: BRC-9, "PERFORM ADJUSTMENT OF STROKE SENSOR: Description". Perform Adjustment of Stroke Sensor
^ Linear solenoid valve: BRC-7, "PERFORM INITIALIZATION OF LINEAR SOLENOID VALVE AND CALIBRATION: Description". Perform Initialization of Linear Solenoid Valve and Calibration
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