C1377

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1377/43: Capacitor Malfunction
C1377/43 - Capacitor Malfunction

DESCRIPTION

The brake control power supply (capacitor) is used as auxiliary power for brake control when battery voltage is low.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK FREEZE FRAME DATA

(a) Check the information code from the "FREEZE FRAME DATA" memorized when the DTC (C1377/43) is stored Freeze Frame Data.

Result

C -- INSPECT AUXILIARY BATTERY

B -- REPLACE BRAKE CONTROL POWER SUPPLY ASSEMBLY Removal
A -- Continue to next step.

2. INSPECT FUSE (ABS MAIN4)

(a) Remove the ABS MAIN4 fuse from the luggage room junction block.

(b) Measure the resistance of the fuse.

Standard resistance:

NG -- REPLACE FUSE
OK -- Continue to next step.

3. CHECK TERMINAL VOLTAGE AND RESISTANCE (+BC, GND)

(a) Disconnect the R72 power supply connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard voltage:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. INSPECT BRAKE CONTROL POWER SUPPLY ASSEMBLY (OUT1, OUT2)

(a) Connect the R72 power supply connector.

(b) Measure the voltage according to the value(s) in the table below.

HINT
Perform inspection while the brake is not operated.

Standard voltage:

Result

B -- RECONFIRM DTC
A -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE CONTROL POWER SUPPLY)

(a) Disconnect the A19 and A21 ECU connectors.

(b) Disconnect the R72 power supply connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:

Result

B -- RECONFIRM DTC

A -- REPAIR OR REPLACE HARNESS OR CONNECTOR

6. INSPECT AUXILIARY BATTERY

(a) Check the auxiliary battery voltage.

Standard voltage:

11 to 14 V

NG -- RECHARGE OR REPLACE AUXILIARY BATTERY Service Precautions
OK -- Continue to next step.

7. INSPECT BRAKE CONTROL POWER SUPPLY ASSEMBLY (+BC TERMINAL)

(a) Disconnect the R72 power supply connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard voltage:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (+BC CIRCUIT)
OK -- Continue to next step.

8. RECONFIRM DTC

(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(b) Turn the power switch ON (IG).

(c) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.

HINT
Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result

B -- REPLACE BRAKE CONTROL POWER SUPPLY ASSEMBLY Removal

A -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting