Advanced Diagnostics

Advanced Diagnostics - DTC P1440 (57): Motor Power Inverter (MPI) Module Output Circuit Malfunction
















General Description
An open in the gate drive-wire, an OFF failure of the motor power inverter (MPI) module, an open in the motor power cable, or an open in the motor coil causes a deviation from the target torque value of the drive motor. The motor control module (MCM) detects these system failures by monitoring each phase current change.

Malfunction Detection 1 (judgment by current deviation) (Fig. 1)
An open in the gate drive-wire or in the motor power cable causes a decrease in the phase current, so the MCM calculates the target output value from the other two phases. A failed phase current value differs from the others. When a difference in phases is detected or if the ratio of the fluctuation range is a specified value for a specified time, a malfunction is detected and a DTC is stored.

Malfunction Detection 2 (judgment by deviation of electrical power) (Fig. 2)
If normal voltage cannot get to the IMA motor because of open circuits in the gate drive-wires, an OFF failure of the MPI module, or a MCM circuit malfunction etc., there is a difference between the target electrical power and the actual motor electrical power. If the electrical deviation is a specified value for a set time, a malfunction is detected and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold

Malfunction Detection 1
The ratio of maximum to minimum for the phase motor current sensor fluctuation values becomes 0.7 or less for at least 0.5 second.

Malfunction Detection 2
The difference between the target electrical power and the actual electrical power is 40 N-m (4 kgf-m, 29.5 lbf-ft) or more for at least 0.5 second.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the MCM memory.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.