DTC C1378: Capacitor Communication Malfunction [10/2020 - 10/2023]: Procedure

1. Make sure that there is no looseness at the locking part and the connecting part of the connector.
2. Disconnect the L101 brake control power supply with bracket assembly connector.
3. Turn the power switch on (IG).
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   L101-3 (IG1) - Body ground	Power switch on (IG)	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT) 

Result: 

OK 

See step  2

1. Turn the power switch off.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   L101-8 (GND) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT) 

Result: 

OK 

See step  3

1. Make sure that there is no looseness at the locking part and the connecting part of the connectors.
2. Disconnect the A11 and A12 skid control ECU assembly connectors.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A11-20 (ENA) - L101-2 (ENA)	Always	Below 1 Ω
   A11-20 (ENA) or L101-2 (ENA) - Body ground	Always	10 kΩ or higher
   A12-30 (FAIL) - L101-7 (FAIL)	Always	Below 1 Ω
   A12-30 (FAIL) or L101-7 (FAIL) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Reconnect the A11 and A12 skid control ECU assembly connectors.
2. Reconnect the L101 brake control power supply with bracket assembly connector.
3. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

   Chassis > ABS/VSC/TRAC > Clear DTCs 

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

   Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

   Chassis > ABS/VSC/TRAC > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1378 is output.	A
   DTC C1378 is not output.	B

Result: 

B 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2020 - 11/2021]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2022]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - 10/2023] 

Result: 

A 

See step  5

1. Check the INF code from the Freeze Frame Data stored when DTC (C1378) was stored.

   Refer to FREEZE FRAME DATA [10/2020 - 10/2023]

   Chassis > ABS/VSC/TRAC > DTC (C1378) > Freeze Frame Data 

   Tester Display
   Detailed Freeze DTC

   Result

   Result	Proceed to
   INF code 112 is output.	A
   INF code 112 is not output.	B

Result: 

A 

REPLACE BRAKE CONTROL POWER SUPPLY WITH BRACKET ASSEMBLY. Refer to  REMOVAL [10/2020 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

Result: 

B 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023]