DTC P323A-19: Backup Boost Converter "A" Circuit Current Above Threshold [12/2019 - 10/2022]: Description

A backup boost converter is built into the engine stop and start ECU.

The backup boost converter helps maintain battery voltage to prevent various functions from failing if power source voltage supplied from the backup boost converter drops due to the high electrical load when the engine is restarted by stop and start control.

The backup boost converter 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.

HINT:

A relay function and fuse function are provided in the backup boost converter.

If there is a malfunction in any of the electrical system circuits connected to the backup boost converter, the fuse and relay functions shut off the malfunctioning circuit to protect other circuits (remains shut off until next trip).

When the electrical system circuit is shut off, power to the circuit is cut off, causing any systems connected to the circuit to be disabled.

The fuse function is reset* when the ignition switch is turned off. If the malfunction still exists in the electrical system circuit that has been shut off by the relay function, it will be shut off again by the relay and fuse functions the next time the ignition switch is turned to ON.

*: A semiconductor fuse self resets according to electric signal.

The backup boost converter supplies power to:

Electronically controlled brake system
Power steering system
Meter / gauge system
Audio and visual system
Navigation system
Rear seat entertainment system
Digital rear-view mirror system
Auto glare-resistant EC mirror
Tire pressure warning system
Lighting system (INT)
Telematics system
Air conditioning system
CAN communication system
Toyota safety sense
Parking support alert system
Headup display system
Blind spot monitor system
Fog light assembly

The external backup boost converter (eco run vehicle converter assembly) supplies power to:

Navigation system

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Memory	Note
P323A-19	Backup Boost Converter "A" Circuit Current Above Threshold	The following condition continues for 1 second or more (1 trip detection logic): Overcurrent is detected at the B41, B42, B43, IG41 and EMOP terminals in the engine stop and start ECU	Wire harness or connector Meter mirror assembly (w/ Headup Display) Integration control sub-assembly (w/ 12.3 Inch Display) Navigation ECU (w/ Navigation System) Tire pressure warning ECU and receiver Radio and display receiver assembly (w/o 12.3 Inch Display) Radio receiver assembly (w/ 12.3 Inch Display) Multi-display assembly (w/ 12.3 Inch Display) Television display assembly (w/ Rear Seat Entertainment System) Inner Rear View Mirror Assembly (w/ EC Mirror or Digital Inner Mirror) Front door ambient light LH (front door trim board sub-assembly LH) (w/ Ambient Illumination Light) Front door ambient light RH (front door trim board sub-assembly RH) (w/ Ambient Illumination Light) Rear door ambient light LH (rear door trim board sub-assembly LH) (w/ Ambient Illumination Light) Rear door ambient light RH (rear door trim board sub-assembly RH) (w/ Ambient Illumination Light) Front passenger side tray illumination light (No. 1 instrument panel light sub-assembly) (w/ Ambient Illumination Light) Center tray illumination light (No. 1 instrument panel light sub-assembly) (w/ Ambient Illumination Light) Blind spot monitor sensor LH Blind spot monitor sensor RH Millimeter wave radar sensor assembly Clearance warning ECU assembly Air conditioning control assembly No. 2 air conditioning control assembly Central gateway ECU (network gateway ECU) Oil pump with solenoid assembly Engine stop and start ECU	Blinks	DTC stored	SAE Code: P323A