DTC C1377/43: Capacitor Malfunction [03/2017 - 09/2018]: Procedure

1. Check the INF code from the Freeze Frame Data stored when DTC (C1377/43) was stored.

   Refer to FREEZE FRAME DATA [03/2017 - 05/2023]

   Result

   Result	Proceed to
   INF codes 109 and/or 110 are output.	A
   INF codes 101, 102, 105, 106 and/or 108 are output.	B
   INF code 103 is output.	C

Result: 

B 

REPLACE BRAKE CONTROL POWER SUPPLY WITH BRACKET ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

Result: 

C 

See step  7

Result: 

A 

See step  2

1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Brake Control Power Supply with Bracket Assembly)

2. Disconnect the X77 brake control power supply with bracket assembly connector.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   X77-5 (+BC) - Body ground	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BC CIRCUIT) 

Result: 

OK 

See step  3

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   X77-8 (GND) - Body ground	Always	Below 1 Ω

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Brake Control Power Supply with Bracket Assembly)

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT) 

Result: 

OK 

See step  4

1. Reconnect the X77 brake control power supply with bracket assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Brake Control Power Supply with Bracket Assembly)

2. Turn the engine switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   1 (OUT1) - Body ground	Engine switch on (IG)	11 to 14 V
   4 (OUT2) - Body ground	Engine switch on (IG)	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE BRAKE CONTROL POWER SUPPLY WITH BRACKET ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

Result: 

OK 

See step  5

1. Turn the engine switch on (IG).

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Skid Control ECU Assembly)

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A9-7 (CBI1) - Body ground	Engine switch on (IG)	8.8 to 14 V
   A10-2 (CBI2) - Body ground	Engine switch on (IG)	8.8 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

Result: 

OK 

See step  6

1. Turn the engine switch off.
2. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

   Chassis > ABS/VSC/TRAC > Clear DTCs 

3. Turn the engine switch off.
4. Turn the engine switch on (IG).
5. Check if the same DTC is output.

   Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

   Chassis > ABS/VSC/TRAC > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1377/43 is not output.	A
   DTC C1377/43 is output.	B

Result: 

A 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020] 

Result: 

B 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

1. Check the battery voltage.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   Battery	Engine switch off	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

CHARGE OR REPLACE BATTERY 

Result: 

OK 

See step  8

1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Brake Control Power Supply with Bracket Assembly)

2. Disconnect the X77 brake control power supply with bracket assembly connector.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   X77-5 (+BC) - Body ground	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (+BC CIRCUIT) 

Result: 

OK 

See step  9

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   X77-8 (GND) - Body ground	Always	Below 1 Ω

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Brake Control Power Supply with Bracket Assembly)

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE BRAKE CONTROL POWER SUPPLY WITH BRACKET ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)