DTC P1774: Speed Command PWM Line: General Description

HEV uses the hydraulic pressure that in addition to mechanical main hydraulic pump, EOP (Electric oil pump) controlled by OPU (oil pump unit) to take command from by PCM/TCM generates to operate engine clutch and U/D brake.

While low speed driving or engine auto stop regardless of driving mode (EV mode or HEV), when hydraulic pressure become low because of mechanical main hydraulic pump rotation in low speed or stop, OPU supplies hydraulic pressure on U/D brake by operating EOP in order to protect Friction Element.

When shifting the driving mode from EV mode to HEV mode, EOP supplies hydraulic pressure to the engine clutch in order to use engine power when the driving mode shift is completed (Engine clutch: wet type diseA00869680 A00869680 clutch that connect or disconnect the engine power between engine input shaft and transaxle input shaft).