DTC P0A08-264: DC / DC Converter Status Circuit [12/2014 - ]: Description
The DC/DC converter converts the DC 144 V of the HV 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 144 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 hybrid vehicle 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 hybrid vehicle control ECU monitors the operation of the DC/DC converter and alerts the driver if it detects a malfunction.
This DTC is stored when the DC/DC converter circuit has a malfunction or its operation is prohibited by a fail-safe function, or the auxiliary battery voltage drops to 11 V or less with the ignition switch to ON (READY). A signal indicating an auxiliary battery malfunction is sent from the DC/DC converter to the hybrid vehicle control ECU via the NODD signal line.
| DTC No. | INF Code | DTC Detection Condition | Trouble Area | Master Warning Light | MIL |
|---|---|---|---|---|---|
| P0A08 | 264 | The DC/DC converter is malfunctioning (charging has stopped) and the auxiliary battery voltage drops to 11 V or less. (1 trip detection logic) The DC/DC converter is malfunctioning for 120 seconds and the inverter coolant water temperature is 70°C or lower. (1 trip detection logic) |
|
Comes on | Does not come on |
| DTC No. | Data List |
|---|---|
| P0A08-264 |
|
The following items can be helpful when performing repair:
Data List
- Ready Signal
- State of Charge (All Bat)
- Prohibit DC/DC conv sig
Operation History Data
- Coolant Heating
- Auxiliary Battery Low
HINT:
- If the NODD signal line is open or shorted to ground, DC/DC converter control will be prohibited and the auxiliary battery voltage will be approximately 12 V (or less).
- When the transistor in the hybrid vehicle control ECU is on, a signal is sent to the inverter via the NODD signal circuit to prohibit DC/DC converter control. When the transistor in the inverter is on, a malfunction signal is sent to the hybrid vehicle control ECU.