DTC P0A78-266: Drive Motor "A" Inverter Performance; DTC P0A78-267: Drive Motor "A" Inverter Performance [08/2013 - ]: Description

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.

The inverter contains a three-phase bridge circuit, which consists of 6 power transistors (IGBTs) each for MG1 and MG2. The inverter converts high-voltage direct current from the HV battery into three-phase alternating current for MG1 and MG2; it also converts three-phase alternating current supplied by MG1 and MG2 into direct current for the HV battery. The MG ECU controls the actuation of the power transistors (IGBTs). The inverter transmits information necessary for control, such as amperage and voltage, to the MG ECU.

HINT:

The term "drive motor A" indicates MG2.

Fig 1: Drive Motor "A" Inverter Wiring Diagram

The MG ECU uses an inverter voltage sensor, which is built into the inverter, to detect boosted high voltage to allow control of the voltage boost.

The MG ECU monitors the inverter voltage sensor and detects the following malfunctions.

DTC No.	INF Code	DTC Detection Condition	Trouble Area
P0A78	266	Short to GND in the inverter voltage (VH) signal line	Inverter with converter assembly
P0A78	267	Open or short to +B in the inverter voltage (VH) signal line	Inverter with converter assembly