C1378 Code: Meaning, Causes, and Symptoms | OBD2 Codes

C1378 – Capacitor Communication Circuit Malfunction

 

C1378 Possible Symptoms

 

Anti-Lock Brake System (ABS) Warning Light ON,Engine Light ON (or Service Engine Soon Warning Light)

 

C1378 Possible Causes

 

Faulty Skid Control ECU,Skid Control ECU harness is open or shorted,Skid Control ECU circuit poor electrical connection

 

C1378 Description

 

The Brake Control Power Supply Assembly (Capacitor) provides auxiliary power for brake control when an auxiliary battery (12 V) voltage drops. The FAIL and ENA line are placed between the Skid Control ECU and the brake control power supply assy. Signals indicating that the brake control power supply is in auxiliary mode are sent to the Skid Control ECU through the FAIL line. Charge permit prohibition signals are sent to the brake control power supply through the ENA line.