DTC P33B3-00: External BBC Circuit [12/2021 - 10/2023]: Description

When the engine is started (high electrical load) from engine stopped by the stop and start control, the external backup boost converter (eco run vehicle converter assembly) supplements battery voltage in order to prevent the function from being disabled due to decrease in power source voltage supplied to the active noise control system.

After receiving a request from the engine stop and start ECU, the external backup boost converter (eco run vehicle converter assembly) helps maintain the power source voltage if the battery voltage drops due to the high electrical load when the engine is restarted by stop and start control. The DON2 terminal of the external backup boost converter (eco run vehicle converter assembly) receives power supply voltage supplement requests from the engine stop and start ECU and switches from idle mode to supplement mode.

When the engine is started by the stop and start control, if the external backup boost converter (eco run vehicle converter assembly) does not maintain the specified voltage, an error is sent to the engine stop and start ECU. Then, the engine stop and start ECU stores DTC P33B3-00, and the stop and start cancel indicator blinks.