C1378

C1378

Description
The brake capacitor provides auxiliary power for brake control when an auxiliary battery (12 V) voltage drops. The FAIL and ENA lines are place between the brake ECU and the brake capacitor.

Signals indicating that the brake capacitor is in auxiliary mode are sent to the brake ECU through the FAIL line. Change permit prohibition signals are sent to the brake capacitor through the ENA line.

C1378:

Diagnosis Procedure

CAUTION:
When replacing the brake ECU, perform initialization of linear solenoid valve and calibration.

1.INSPECT BRAKE CAPACITOR (IG1 TERMINAL)
1. Disconnect the brake capacitor connector.
2. Turn the ignition switch ON.
3. Measure the voltage according to the value(s) in the table below.





Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair or replace harness or connector (IG1 circuit).

2.INSPECT BRAKE CAPACITOR (GND TERMINAL)
1. Turn the ignition switch OFF.
2. Measure the resistance according to the value(s) in the table below.





Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace harness or connector (GND circuit).

3.CHECK HARNESS AND CONNECTOR (BRAKE ECU - BRAKE CAPACITOR)
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 4.
NO >> Repair or replace harness or connector.

4.RECONFIRM DTC
1. Reconnect the brake ECU connector and the brake capacitor connector.
2. Clear the DTC.
3. Turn the ignition switch ON.
4. Check if the same DTC is recorded.

Result:

A >> GO TO 5.
B >> Check for intermittent problems (symptom simulation).

5.CHECK FREEZE FRAME DATA
Check the INF code from the Freeze Frame Data memorized when the DTC (1378) is stored.

Result:

A >> Replace brake ECU.
B >> Replace brake capacitor.

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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