DTC 278

DTC 278 DRIVE MOTOR "A" INVERTER PERFORMANCE

CIRCUIT DESCRIPTION

DTC Detection Condition:

The inverter converts the high-voltage direct current of the HV battery and the alternating current for the MG1/MG2. The inverter contains a three-phase bridge circuit, which consists of six power transistors each for the MG1 and the MG2, in order to convert the direct current and the three-phase alternating current. The HV control ECU controls the actuation of the power transistors. The inverter transmits information that is necessary for effecting control, such as the amperage and voltage, to the HV control ECU.

The HV control ECU uses a voltage sensor, which has been built into the inverter, to detect the high voltage after it is boosted and for boost control. The inverter voltage sensor outputs a voltage that varies between 0 and 5 V in accordance with the changes in the high voltage. The higher the high voltage, the higher the output voltage, and the lower the high voltage, the lower the output voltage. The HV control ECU monitors the inverter voltage and detects malfunction.

If the motor inverter detects a circuit malfunction or over-voltage, the inverter transmits this information to the OVH terminal of the HV control ECU via the motor inverter over-voltage signal line.

The HV control ECU monitors the motor inverter over-voltage signal line to detect the malfunction.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Component Operating Range:

The HV control ECU monitors the motor inverter over-voltage (OVH) signal line. If the HV control ECU detects an open or short malfunction of the OVH signal circuit, the HV control ECU illuminates the MIL and sets a DTC.

Wiring Diagram:

Step 1:

INSPECTION PROCEDURE

CAUTION:
- Before inspecting the high-voltage system, take safety precautions to prevent electrical shocks, such as wearing insulated gloves and removing the service plug grip. After removing the service plug grip, put it in your pocket to prevent other technicians from reconnecting it while you are servicing the high-voltage system.
- After disconnecting the service plug grip, wait for at least 5 minutes before touching any of the high-voltage connectors or terminals.

HINT: At least 5 minutes is required to discharge the high-voltage condenser inside the inverter.