Circuit Functions
The IPR is a pulse width modulated (PWM) variable position valve that regulates the pressure in the injection control pressure (ICP) system. The IPR restricts the return flow path for oil from the high pressure pump. As the duty cycle increases, the IPR restriction to the drain increases, thus increasing the ICP. The IPR duty cycle is controlled by the powertrain control module (PCM) and is modulated from 0 to 65% depending upon the desired injection control pressure.