DTC P0A08-264: DC / DC Converter Status Circuit: Description

The DC/DC converter converts the DC 277.5 V of the EV battery into DC 12 V in order to supply power to areas such as the vehicle's lighting, audio, and ECU systems. In addition, it charges the auxiliary battery.

A transistor bridge circuit initially converts DC 277.5 V into alternating current, and a transformer lowers its voltage. Then, it is rectified and smoothed (into DC) and converted into DC 12 V.

The DC/DC converter controls the output voltage in order to keep a constant voltage at the terminals of the auxiliary battery.

The power management control ECU uses the NODD signal line to transmit a stop command to the DC/ DC converter and receive signals indicating the normal or abnormal condition of the 12 V charging system.

If the vehicle is being driven with an inoperative DC/DC converter, the voltage of the auxiliary battery will drop, which will prevent the continued operation of the vehicle. Therefore, the power management control ECU monitors the operation of the DC/DC converter and alerts the driver if it detects a malfunction.

Fig 1: DC/DC Converter System Diagram

DTC No.	INF Code	DTC Detection Condition	Trouble Area
P0A08	264	DC/DC converter malfunction	Wire harness or connector Water pump with motor assembly Inverter cooling system EV transaxle with motor assembly Motor cable Frame wire Inverter with converter assembly Fuse (DCDC-S, IGCT, IGCT NO. 2) Fusible link (DC/DC) Power management control ECU